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Dimitry Goder Randy Flatness INTRODUCTION High efficiency frequently main goal power supplies portable computers hand-held equipment. Efficient converters necessary these applications minimize power drain input source (batteries, etc.) heat buildup power components, allowing smaller, lighter, longer-lived systems. Power conversion efficiency must range order meet these goals. This application note features power supply circuits that satisfy these design requirements attain high efficiency over wide operating range. recent development LTC®1142, LTC1143, LTC1147, LTC1148, LTC1149 makes ultra-high efficiency conversion possible. addition, LTC1148, LTC1149, LTC1142 synchronous switching regulators, achieving high efficiency conversion output currents excess 10A. These controllers feature current mode architecture that automatic Burst Modeoperation currents. This technology makes efficiencies possible output currents 10mA, maximizing battery life while product sleep standby mode. These ultra-high efficiency converters also implement constant off-time architecture, fully synchronous switching dropout regulation. these features make this series converters really excellent choice vast variety applications. Achieving high efficiency primary goals switching regulator design. Every application circuit shown this note includes detailed efficiency graphs. Almost magnetic parts used circuits standard products, available off-the-shelf from various manufacturers.
registered trademarks trademark Linear Technology Corporation. Burst Mode trademark Linear Technology Corporation.
AN54-1
Application Note
TABLE CONTENTS
Buck LTC1148: (5V-14V 5V/1A) Buck Converter with Surface Mount Technology Figure LTC1148: (5V-14V 5V/2A) Buck Converter Figure LTC1148: (5V-14V 5V/2A) High Frequency Buck Converter with Surface Mount Technology. Figure LTC1148: (4V-14V 3.3V/1A) Buck Converter with Surface Mount Technology Figure LTC1148: (4V-14V 3.3V/2A) Buck Converter with Surface Mount Technology Figure LTC1148: 3.3V/5A) High Efficiency Step-Down Converter Figure LTC1148: 3.5V/3A) High Efficiency Step-Down Converter Figure LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter Figure LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter with Large P-Channel N-Channel MOSFETs Figure LTC1149: (10V-48V 3.3V/2A) High Voltage Buck Converter Figure LTC1149: (10V-48V 12V/2A) High Voltage Buck Converter Figure LTC1149: (16VRMS 13.8/10A) Buck Converter Figure LTC1149: (32VRMS 27.6V/5A) Buck Converter Figure LTC1147: (5V-14V 5V/1A) Buck Converter with Surface Mount Technology Figure LTC1147: (4V-14V 3.3V/1A) Buck Converter with Surface Mount Technology Figure LTC1147: (4V-8V 3.3V/1.5A) Buck Converter with Surface Mount Technology Figure LTC1148: (10V-14V 5V/10A) High Current Buck Convert Figure LTC1149: (12V-36V 5V/5A) High Current, High Voltage Buck Converter Figure LTC1149: (12V-48V 5V/10A) High Current, High Voltage Buck Converter Figure LTC1149: (32V-48V 24V/10A) High Current, High Voltage Buck Converter Figure LTC1143: (5.2V-14V 3.3V/2A 5V/2A) Dual Buck Converter Figure LTC1148HV-5: (5.2V-18V 5V/1A) High Voltage Buck Converter Figure LTC1148HV-3.3 (4V-18V 3.3V/1A) High Voltage Buck Converter Figure LTC1148HV: (12.5V-18V 12V/2A) High Voltage Buck Converter Figure LTC1142: (6.5V-14V 3.3V/2A, 5V/2A, 12V/0.15A) Triple Output Buck Converter Figure LTC1142HV: (6.5V-18V 3.3V/2A, 5V/2A, 12V/0.15A) High Voltage Triple Output Buck Converter Figure Single LTC1149: Dual Output Buck Converter Figure LTC1148: (8V-15V 5V/2A) Constant Frequency Buck Converter Figure LTC1148: (4.5V-6.5V 3.3V/2A) Constant Frequency Buck Converter. Figure Buck-Boost Inverting Topologies LTC1148: (4V-14V 5V/1A) SEPIC Converter Figure LTC1148: (4V-14V 5V/0.5A, 5V/0.5A) Split Supply Converter Figure LTC1148: (4V-10V 5V/1A) Positive-to-Negative Converter Figure LTC1148: (5V-12V -15V/0.5A) Buck-Boost Converter Figure Boost LTC1148: (2V-5V 5V/1A) Boost Converter Figure Battery Charging Circuits LTC1148: High Efficiency Charger Circuit Figure LTC1148: High Voltage Charger Circuit Figure LTC1142A: High Efficiency Power Supply Providing 3.3V/2A with Built-In Battery Charger Figure Appendix Topics Common Interest Appendix Suggested Manufacturers AN54-3 AN54-4 AN54-5 AN54-6 AN54-7 AN54-8 AN54-9 AN54-10 AN54-11 AN54-12 AN54-13 AN54-14 AN54-15 AN54-16 AN54-17 AN54-18 AN54-19 AN54-20 AN54-21 AN54-22 AN54-28 AN54-29 AN54-30 AN54-31 AN54-32 AN54-34 AN54-38 AN54-39 AN54-40 AN54-23 AN54-24 AN54-25 AN54-26 AN54-27 AN54-35 AN54-36 AN54-37 AN54-40 AN54-42
AN54-2
Application Note
LTC1148: (5V-14V 5V/1A) Buck Converter with Surface Mount Technology basic LTC1148 application shown Figure This conventional step-down converter that provides output maximum output current. components used surface mounted heat sink required. During on-time, inductor L1's current sensed monitored internal current sensing comparator. filter noise from current sense waveform, added circuit. When current ramp reaches preset value, turned off, clamp diode starts conducting short period time, until internal control logic senses that completely off. Then NDRIVE output goes high turning which shorts This provides synchronous rectification significantly reduces conduction losses during Q1's off-time. This regulator constant off-time defined timing capacitor control output, on-time varied, changing operating frequency therefore, duty cycle. input voltage reduced, frequency decreases keeping output voltage same level. Q1's on-time stretches infinity with input voltage, providing 100% duty cycle very dropout. Under dropout conditions, output voltage follows input, less resistive losses Under conditions light output currents, regulator enters Burst Mode operation ensure high efficiency. Continuous operation interrupted internal voltage sensing comparator with built-in hysteresis. this mode both turned comparator monitors decreasing output voltage. When output capacitor discharges below fixed threshold, operation resumes short period time bringing output voltage back normal. Then regulator shuts down again conserving quiescent current. Under Burst Mode operation output ripple typically 50mV hysteresis comparator.
0.1µF PDRIVE SHUTDOWN LTC1148-5 SENSE SENSE 390pF NDRIVE SGND PGND 0.01µF Si9430DY
22µF
100µH
3300pF
Si9410DY MBRS140T3
220µF
(Ta) (Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY
SP-1/2-A1-0R100J 0.75W COILTRONICS CTX100-4 0.175 Kool CORE OTHER CAPACITORS CERAMIC
AN54 F01A
QUIESCENT CURRENT 180µA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 200mA
Figure LTC1148: (5V-14V 5V/1A) Buck Converter with Surface Mount Technology
Kool registered trademark Magnetics, Inc.
AN54-3
Application Note
Figure shows efficiency versus output current three different input voltages. Generally speaking, efficiency drops function input voltage gate charge losses LTC1148 bias current. curves converge maximum output current these losses become less significant.
EFFICIENCY
LTC1148: (5V-14V 5V/2A) Buck Converter step-down regulator with output current capability shown Figure provide higher output power levels sense resistor value decreased, thus increasing current limit. This also increases maximum allowable ripple current inductor, value reduced. Note that timing capacitor changed optimize performance standard inductor value. this Figure consists parallel capacitors ensuring minimum capacitance requirement conditions. circuit board been laid this circuit subsequently been thoroughly tested under full operating conditions optimized mass production requirements. Gerber file board available upon request.
0.001
0.01 OUTPUT CURRENT
AN54 F01B
Figure LTC1148: (5V-14V 5V/1A) Buck Converter Measured Efficiency
0.1µF PDRIVE SHUTDOWN LTC1148-5 SENSE SENSE 470pF SGND NDRIVE PGND 0.01µF Si9430DY
22µF
62µH
0.05
3300pF
Si9410DY MBRS140T3
220µF
(Ta) (Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY 1-C1-0R050J COILTRONICS CTX62-2-MP 0.040 CORE (THROUGH HOLE)
QUIESCENT CURRENT 180µA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 400mA
AN54 F02A
OTHER CAPACITORS CERAMIC
Figure LTC1148: (5V-14V 5V/2A) Buck Converter
AN54-4
Application Note
EFFICIENCY
LTC1148: (5V-14V 5V/2A) High Frequency Buck Converter with Surface Mount Technology
Figure presents essentially same circuit Figure implementing changes operate higher frequency. Timing capacitor reduced achieve higher switching rate. This approach allows smaller value inductor with surface mount technology, resulting more compact design.
0.001
0.01 OUTPUT CURRENT
AN54 F02B
Figure LTC1148: (5V-14V 5V/2A) Buck Converter Measured Efficiency
0.1µF PDRIVE SHUTDOWN Si9430DY LTC1148-5 SENSE SENSE 220pF SGND NDRIVE PGND
22µF 33µH 0.05
0.01µF
3300pF
Si9410DY MBRS140T3
220µF
(Ta) (Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY SL-1-C1-0R050J COILTRONICS CTX33-4 0.06 Kool CORE
QUIESCENT CURRENT 180µA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 400mA
AN54 F03A
OTHER CAPACITORS CERAMIC
Figure LTC1148: (5V-14V 5V/2A) High Frequency Buck Converter with Surface Mount Technology
AN54-5
Application Note
compare efficiency graphs Figures Gate charge losses directly proportional operating frequency, result efficiency Figure
decreased. However, effect most noticeable high input voltages currents. maximum load losses dominate that regulator performance varies only slightly. These circuits illustrate fact that best overall efficiency reached moderate frequencies. They represent nice example compromising between regulator compactness efficiency. LTC1148: (4V-14V 3.3V) Buck Converters with Surface Mount Technology Figures show application circuits LTC1148-3.3 which provides fixed 3.3V output. circuits deliver output currents, exactly same circuit configuration component values Figures Even though LTC1148 achieve dropout, minimum input voltage limited meet requirements power MOSFET gate drive, ensure proper operation LTC1148 internal circuitry.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F03B
Figure LTC1148: (5V-14V 5V/2A) High Frequency Buck Converter Measured Efficiency
0.1µF PDRIVE SHUTDOWN Si9430DY LTC1148-3.3 SENSE SENSE 560pF SGND NDRIVE PGND
22µF 100µH 3.3V
0.01µF
3300pF
Si9410DY MBRS140T3
220µF
(Ta) (Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY SP-1/2-A1-0R100J 0.75W COILTRONICS CTX100-4 0.175 Kool CORE
QUIESCENT CURRENT 180µA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 250mA
AN54 F04A
OTHER CAPACITORS CERAMIC
Figure LTC1148: (4V-14V 3.3V/1A) Buck Converter with Surface Mount Technology
AN54-6
Application Note
output voltage causes efficiency degradation light loads when chip's supply current gate charge current play major parts total losses. Figures
EFFICIENCY
illustrate this point efficiency falls below 10mA output current. High input voltage compounds problem.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F04B
0.001
0.01 OUTPUT CURRENT
AN54 F05B
Figure LTC1148: (4V-14V 3.3V/1A) Buck Converter Measured Efficiency
Figure LTC1148: (4V-14V 3.3V/2A) Buck Converter Measured Efficiency
0.1µF PDRIVE SHUTDOWN Si9430DY
22µF
50µH
0.05
3.3V
LTC1148-3.3 SENSE SENSE
0.01µF
3300pF
Si9410DY MBRS140T3
470pF
NDRIVE SGND PGND
220µF
(Ta) (Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY SL-1-C1-0R050J COILTRONICS CTX50-2-MP 0.032 CORE (THROUGH HOLE)
QUIESCENT CURRENT 180µA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 450mA
AN54 F05A
OTHER CAPACITORS CERAMIC
Figure LTC1148: (4V-14V 3.3V/2A) Buck Converter with Surface Mount Technology
AN54-7
Application Note
LTC1148: 3.3V/5A) High Efficiency Step-Down Converter Many microprocessor designs require 3.3V, they used systems where primary source power. high efficiency 3.3V converter drawn Figure supplies load using only surface mount components. P-channel MOSFETs connected parallel decrease their conduction losses. Efficiency input 90%; this means only 1.6W lost. lost power distributed between RSENSE, power MOSFETs, thus heat sinking required.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F06B
Figure LTC1148: 3.3V/5A) Buck Converter Measured Efficiency
0.1µF
PDRIVE
Si9433DY
Si9433DY
33µF 6.3V VOUT 3.3V
LTC1148-3.3
NORMAL SHUTDOWN
0.02
SHUTDOWN
SENSE SENSE
0.01µF
3300pF 150pF
NDRIVE SGND PGND
Si9410DY
MBRS140T3
220µF
TANTALUM PANASONIC ECG-COJB330 (Ta) TPSE227K01R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS DCRON 0.075 60nC SILICONIX NMOS BVDSS DCRON 0.050 30nC MOTOROLA SCHOTTKY MP-2A-C1-0R020J COILTRONICS CTX02-12483-1
AN54 F06A
Figure LTC1148: 3.3V/5A) High Efficiency Step-Down Converter
AN54-8
Application Note
LTC1148: 3.5V/3A) High Efficiency Step-Down Converter Some processors require 3.5V other intermediate voltage derived from supply. good solution them circuit Figure adjustable version LTC1148 allows precise output voltage adjustment, while preserving efficiencies 95%. output voltage resistors
EFFICIENCY
0.001 0.01 OUTPUT CURRENT
AN54 F07B
Figure LTC1148: 3.5V/3A) Measured Efficiency
Si9433DY
MBRS130T3
22µF
0.1µF 180pF 3300pF
PDRIVE SENSE
NDRIVE PGND SGND SHUTDOWN SENSE 0.01µF
SHUTDOWN 0.033 10µH
Si9410DY
LTC1148
100pF
18.2k
100µF
(Ta) TPSD226M025R0200 0.20 IRMS 0.866A (Ta) TPSD107M01R0100 0.10 IRMS 1.225A SILICONIX PMOS BVDSS DCRON 0.110 20nC SILICONIX NMOS BVDSS DCRON 0.05 30nC MOTOROLA SCHOTTKY SL-C1-1/2-0R033J 1/2W COILTRONICS CTX10-4 0.038 Kool CORE
VOUT 1.25V R3/R4)
F07A
Figure LTC1148: 3.5V/3A) High Efficiency Step-Down Converter
VOUT
3.5V
AN54-9
Application Note
LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter Previous circuits accept inputs 14V. higher input voltage required LTC1149 used. This designed inputs 48V. basic step-down application circuit shown Figure operates same fashion circuit Figure provides 5V/2A output. However, different MOSFETs used since they must withstand between source drain. High current efficiency exceeds over wide range input voltages. Since control drive circuitry powered directly from input line, bias current gate charge current result slightly lower efficiency light moderate loads high input voltage (relative LTC1148). This characteristic eliminated circuit Figure 11A. circuit board been laid this circuit subsequently been thoroughly tested under full operating conditions optimized mass production requirements. Gerber file board available upon request.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F08B
Figure LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter Measured Efficiency
0.1µF SGND PGND NGATE RGND IRFU024 PGATE PDRIVE LTC1149-5 SENSE SENSE 0.047µF 1N4148 IRFU9024
330µF
0.1µF
0.068µF
62µH
0.05
0.01µF
MBR160
3300pF
680pF
220µF
UNITED CHEMI-CON (Al) LXF63VB331M12.5 0.170 IRMS 1.280A (Ta) SANYO (OS-CON) 10SA22OM 0.035 IRMS 2.360A PMOS BVDSS RDSON 0.280 CRSS 65pF 19nC NMOS BVDSS RDSON 0.100 CRSS 79pF 28nC SILICON MOTOROLA SCHOTTKY NP-1A-C1-0R050J COILTRONICS CTX62-2-MP 0.040 CORE
QUIESCENT CURRENT 1.5mA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 570mA
AN54 F08A
OTHER CAPACITORS CERAMIC
Figure LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter
AN54-10
Application Note
LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter with Large P-Channel N-Channel MOSFETs Figure similar Figure with much larger MOSFETs (TO220 package). These transistors have lower RDS(ON) which reduces their losses roughly factor However, efficiency improves (compared Figure only output current with minimum input voltage. Under other conditions higher gate capacitance causes increased gate charge current leading higher driver loss. Also high input voltages (roughly greater than 24V), transition losses play significant part. These losses proportional reverse transfer capacitance CRSS, maximum output current, square input voltage. Larger CRSS oversized P-channel MOSFET causes efficiency drop (especially higher input voltages). Remember, "best" MOSFET selection depends particular application.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F09B
Figure LTC1149: (10V-48V 5V/2A) Measured Efficiency with Large P-Channel N-Channel MOSFETs
0.1µF SGND NGATE RGND IRFZ34 PGATE PDRIVE LTC1149-5 SENSE SENSE 0.047µF 1N4148 IRF9Z34
330µF
0.1µF
0.068µF
62µH
0.05
0.01µF
MBR160
3300pF
680pF
220µF
PGND
UNITED CHEMI-CON (Al) LXF63VB331M12.5 0.170 IRMS 1.280A (Ta) SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A PMOS BVDSS RDSON 0.140 CRSS 100pF 34nC NMOS BVDSS RDSON 0.050 CRSS 100pF 32nC SILICON MOTOROLA SCHOTTKY NP-1A-C1-0R050J QUIESCENT CURRENT 1.5mA COILTRONICS CTX62-2-MP 0.040 CORE TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 560mA
AN54 F09A
OTHER CAPACITORS CERAMIC
Figure LTC1149: (10V-48V 5V/2A) High Voltage Buck Converter with Large P-Channel N-Channel MOSFETs
AN54-11
Application Note
LTC1149: (10V-48V 3.3V/2A) High Voltage Buck Converter 3.3V generated efficiently from high voltage input, circuit Figure 10A. copies configuration presented Figure uses LTC1149-3.3 regulator provide precise 3.3V output. spite high input output voltages, efficiency still reaches 92%.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F10B
Figure 10B. LTC1149: (10V-48V 3.3V/2A) High Voltage Buck Converter Measured Efficiency
0.1µF SGND NGATE PGND RGND IRFU024 PGATE PDRIVE LTC1149-3.3 SENSE SENSE 0.047µF 1N4148 IRFU9024
330µF
0.1µF 0.068µF
50µH
0.05
3.3V
0.01µF
MBR160
3300pF
470pF
220µF
UNITED CHEMI-CON (Al) LXF63VB331M12.5 0.170 IRMS 1.280A (Ta) SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A PMOS BVDSS RDSON 0.280 CRSS 65pF 19nC NMOS BVDSS RDSON 0.100 CRSS 79pF 28nC SILICON MOTOROLA SCHOTTKY NP-1A-C1-0R050J COILTRONICS CTX50-2-MP 0.032 CORE
QUIESCENT CURRENT 1.5mA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 570mA
AN54 F10A
OTHER CAPACITORS CERAMIC
Figure 10A. LTC1149: (10V-48V 3.3V/2A) High Voltage Buck Converter
AN54-12
Application Note
LTC1149: (10V-48V 12V/2A) High Voltage Buck Converter LTC1149 contains internal dropout linear regulator provide power control circuitry. actually means that bias current well gate charge current come directly from input line, causing slight efficiency degradation, especially high input voltages (additional power dissipated internal regulator). solution this problem presented Figure 11A. When output level reaches about Zener starts conducting saturates which turn switches pins powered directly from output. Losses caused current gate charge current significantly reduced allowing improved efficiency high input voltage. regulator output must output voltage less than 14.5V provide margin LTC1149 absolute maximum rating 16V. should also observed that turns when output less than (the internal regulator output) stays under conditions.
EFFICIENCY
0.001 0.01 OUTPUT CURRENT
AN54 F11B
Figure 11B. LTC1149: (10V-48V 5V/2A) Measured Efficiency with Large P-Channel N-Channel MOSFETs
2N3906
0.1µF
1N4148 PGATE PDRIVE SENSE SENSE LTC1149 NGATE RGND
1N4148
330µF
IRF9Z34 0.047µF
0.1µF 0.068µF
62µH
0.05
VOUT 432k
5.1V
SGND
0.01µF
IRFZ34 MBR160 49.9k
2N3904 3300pF
220µF
200pF
PGND
UNITED CHEMI-CON (Al) LXF63VB331M12.5 0.170 IRMS 1.280A (Ta) SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A PMOS BVDSS RDSON 0.140 CRSS 100pF 34nC NMOS BVDSS RDSON 0.050 CRSS 100pF 32nC SILICON MOTOROLA SCHOTTKY NP-1A-C1-0R050J COILTRONICS CTX62-2-MP 0.040 CORE
QUIESCENT CURRENT 1.5mA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 560mA
AN54 F11A
OTHER CAPACITORS CERAMIC
Figure 11A. LTC1149: (10V-48V 12V/2A) High Voltage Buck Converter
AN54-13
Application Note
LTC1149: High Power Buck Converters Figures examples high power (more than 100W) converters that LT1149. regulators powered from full wave rectified output 16VRMS 32VRMS transformer. Input capacitance very bulky, ensure that ripple valleys below minimum regulator input requirement. circuit Figure additional gate driver circuits which required improve MOSFET switching times. Overall efficiency goes high 98%! Remember, these output current levels layout becomes extremely important, recommendations from LTC1149 data sheet must closely followed.
EFFICIENCY
0.01
OUTPUT CURRENT
AN54 F12B
Figure 12B. LTC1149: (16VRMS 13.8V/10A) Buck Converter Measured Efficiency
0.33µF
0.22µF 0.33µF
1N4148
16VRMS RECTIFIED RFG60P06E MBR380 1.5µF WIMA
20000µF
270pF 3300pF WIMA
10µF
PGATE PDRIVE SENSE LTC1149
RGND NGATE PGND SGND SENSE
100pF 205k 20.5k SHUTDOWN (NORMALLY GND)
IRFZ44
33µH
COUT, 1500µF 25V,
VOUT 13.8V
1000pF
0.0082 OUTPUT GROUND CONNECTION
AN54 F12A
COUT PANASONIC SERIES MOTOROLA SCHOTTKY HARRIS PMOS RDSON 0.03
Figure 12A. LTC1149: (16VRMS 13.8V/10A) Buck Converter
AN54-14
Application Note
MPSW06 0.33µF 0.22µF 0.33µF MPSA56 PDRIVE BUFFER 150pF 3300pF WIMA COUT PANASONIC SERIES MOTOROLA SCHOTTKY SILICONIX PMOS RDSON 0.045 1000pF OUTPUT GROUND CONNECTION
AN54 F13A
1N4148 SMP40P06 MBR380 1.5µF WIMA
32VRMS RECTIFIED
5000µF
10µF
PGATE PDRIVE SENSE LTC1149
RGND NGATE PGND SGND SENSE
100pF 432k 20.5k 1N4148 MPSA56 NDRIVE BUFFER SHUTDOWN (NORMALLY GND)
IRFZ34
62µH
COUT, 1000µF
VOUT 27.6V
0.016
Figure 13A. LTC1149: (32VRMS 27.6V/5A) Buck Converter
EFFICIENCY
0.01
OUTPUT CURRENT
AN54 F13B
Figure 13B. LTC1149: (32VRMS 27.6V/5A) Buck Converter Measured Efficiency
AN54-15
Application Note
LTC1147: (5V-14V 5V/1A) Buck Converter with Surface Mount Technology LTC1147 (Figure 14A) great implement high efficiency regulator using minimum number external components occupying least board space. This regulator provides many advantages LTC1148 including constant off-time configuration, dropout regulation Bust Mode operation, comes smaller package does require N-channel MOSFET. only sacrifice made synchronous rectification which degrades efficiency this circuit three percentage points. Compare efficiency graphs Figures 14B! Since clamp diode conducts time during off-time, larger diode (MBRD330) used this circuit. LTC1147 excellent choice where output current less than where input voltage less than twice output voltage.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F14B
Figure 14B. LTC1147: (5V-14V 5V/1A) Buck Converter Measured Efficiency
0.1µF SHUTDOWN LTC1147-5 SENSE SENSE 390pF MBRD330 PDRIVE Si9430DY
22µF 100µH
0.001µF
3300pF
220µF
(Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC MOTOROLA SCHOTTKY SP-1/2-A1-0R100J 0.75W COILTRONICS CTX100-4 0.175 Kool CORE
QUIESCENT CURRENT 190µA TRANSITION CURRENT (Burst Mode OPERATION/ CONTINUOUS OPERATION) 170mA
AN54 F14A
OTHER CAPACITORS CERAMIC
Figure 14A. LTC1147: (5V-14V 5V/1A) Buck Converter with Surface Mount Technology
AN54-16
Application Note
LTC1147: (4V-14V 3.3V/1A) Buck Converter with Surface Mount Technology Figure shows another compact circuit with LTC1147 series. generates 3.3V/1A output using same configuration previous example. Despite lack synchronous rectification, efficiency approaches with input.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F15B
Figure 15B. LTC1147: (4V-14V 3.3V/1A) Buck Converter Measured Efficiency
0.1µF PDRIVE SHUTDOWN LTC1147-3.3 SENSE SENSE 560pF MBRD330 Si9430DY
22µF 100µH 3.3V
0.001µF
3300pF
220µF
(Ta) TPSD226K025R0200 0.200 IRMS 0.775A (Ta) TPSE227K010R0080 0.080 IRMS 1.285A SILICONIX BVDSS DCRON 0.100 CRSS 400pF 50nC MOTOROLA SP-1/2-A1-0R100 0.75W COILTRONICS CTX100-4 0.175 Kool CORE
QUIESCENT CURRENT 170µA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 170mA
AN54 F15A
Figure 15A. LTC1147: (4V-14V 3.3V/1A) Buck Converter with Surface Mount Technology
AN54-17
Application Note
LTC1147: (4V-8V 3.3V/1.5A) Buck Converter with Surface Mount Technology more application circuit with LTC1147 presented Figure 16A. optimized 3.3V conversion with input voltages (limited P-channel MOSFET). circuit board been laid this circuit subsequently been thoroughly tested under full operating conditions optimized mass production requirements. Gerber file board available upon request.
EFFICIENCY
0.001 0.01 OUTPUT CURRENT LTC1147-3.3 SUMIDA CDR74B LTC1147-3.3 SUMIDA CD54
AN54 F16B
Figure 16B. LTC1147: (4V-8V 3.3/1.5A) Buck Converter Measured Efficiency
0.1µF NORMAL SHUTDOWN PDRIVE SHUTDOWN 10µH P-CH Si9433DY
47µF
0.068
VOUT 3.3V 1.5A
LTC1147-3.3 SENSE SENSE
0.01µF
MBRS130LT3
100µF
3300pF
120pF
AN54 F16A
TPSD476M016R0150 TANTALUM 47µF TPSD107M010R0100 TANTALUM 100µF MOTOROLA MBRS130LT3 SUMIDA CDR74B-100LC SILICONIX PMOS Si9433 LRC-LR2010-01-R068-F OTHER CAPACITORS CERAMIC
Figure 16A. LTC1147: (4V-8V 3.3V/1.5A) Buck Converter with Surface Mount Technology
AN54-18
Application Note
LTC1148: (10V-14V 5V/10A) High Current Buck Converter differences physical structure between Pchannel MOSFETs, former usually more cost effective, more available, provide better internal parameters same size. This especially important when high output currents required. With output currents N-channel MOSFETs place P-channel most preferable solution. implementation this idea presented Figure 17A. special gate drive circuit that uses bootstrapping technique added provide required gate drive. When goes high turns providing path fast gate capacitance discharge. With off, saturate each other feeding positive voltage Q4's gate. result turns positive pulse source coupled through supplying bootstrapped gate drive "SCR." external driver circuit contains only inexpensive, readily available small-signal transistors, allows N-channel MOSFETs. Efficiency reaches (see Figure 17B).
EFFICIENCY
OUTPUT CURRENT
AN54 F17B
Figure 17B. LTC1148: (10V-14V 5V/10A) High Current Buck Converter Measured Efficiency
1N4148 0.47µF 2N2222 PDRIVE SHUTDOWN 1N4148
2N3906
2700µF
0.1µF
IRFZ44 33µH 0.01
VN2222LL
LTC1148-5 SENSE SENSE
0.001µF
3300pF
820pF
NDRIVE SGND PGND
IRFZ44 1N5818
2200µF
(Ta) UNITED CHEMI-CON (Al) LXF35VB272M16 0.018 IRMS 2.900A NICHICON (Al) UPL1C222MRH 0.028 IRMS 2.010A NMOS BVDSS DCRON 0.028 CRSS 310pF 69nC MOTOROLA SILICON MOTOROLA SCHOTTKY
NP-2A-C1-0R010J COILTRONICS CTX33-10-KM 0.010 Kool CORE
OTHER CAPACITORS CERAMIC QUIESCENT CURRENT 22mA
AN54 F17A
Figure 17A. LTC1148: (10V-14V 5V/10A) High Current Buck Converter
AN54-19
Application Note
resistors placed series with current sense pins. This significantly improves circuit noise immunity which great importance when switching high current. connected between ground, disables Burst Mode operation that regulator operates continuously. LTC1149: (12V-36V 5V/5A) High Current, High Voltage Buck Converter Figure shows high current, high voltage buck converter. LTC1149 used accommodate input voltage requirement. Figure N-channel MOSFET driven external circuit which inverts chip's P-drive output uses bootstrapping provide positive gate-source voltage. peak-to-peak gate voltage defined portion gate driver VCC. Therefore, exceed maximum gate voltage MOSFET, D1's anode connected internal regulator output. this application PDRIVE used because output referenced ground required. PGATE provides same drive signal referenced VCC.
EFFICIENCY
OUTPUT CURRENT
AN54 F18B
Figure 18B. LTC1149: (12V-36V 5V/5A) High Current, High Voltage Buck Converter Measured Efficiency
1N4148 0.1µF SGND PGND NGATE RGND LTC1149-5 SENSE SENSE PGATE PDRIVE
2N3906
1000µF
1N4148
0.22µF 2N2222 MTP30N06EL
0.1µF
VN2222LL
50µH
0.02
0.001µF IRFZ34 MBR160
3300pF
820pF
220µF
(Ta) NICHICON (Al) UPL1J102MRH 0.027 IRMS 2.370A SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A BVCEO SILICONIX NMOS BVDSS RDSON 5.000 MOTOROLA NMOS BVDSS RDSON 0.050 CRSS 100pF 40nC
NMOS BVDSS RDSON 0.050 CRSS 100pF 32nC SILICON MOTOROLA SCHOTTKY NP-2A-C1-0R020J COILTRONICS CTX50-5-52 0.021 IRON POWDER CORE
AN54 F18A
OTHER CAPACITORS CERAMIC
Figure 18A. LTC1149: (12V-36V 5V/5A) High Current, High Voltage Buck Converter
AN54-20
Application Note
LTC1149: (12V-48V 5V/10A) High Current, High Voltage Buck Converter circuit Figure uses same configuration designed provide output current. Besides usual external component changes, circuit uses higher current MOSFETs improve efficiency maximum power levels. Efficiency output several percentage points better than previous example (compare Figures 19B). keeps regulator continuous mode causing rapid efficiency decrease lighter loads.
EFFICIENCY
OUTPUT CURRENT
AN54 F19B
Figure 19B. LTC1149: (12V-48V 5V/10A) High Current, High Voltage Buck Converter Measured Efficiency
1N4148
0.1µF SGND PGND NGATE RGND PGATE PDRIVE LTC1149-5 SENSE SENSE
2N3906
1000µF
1N4148
0.22µF 2N2222 IRFZ34
0.1µF
VN2222LL
33µH
0.01
0.001µF MBR160
3300pF
820pF
IRFZ44
220µF
(Ta) NICHICON (Al) UPL1J102MRH 0.027 IRMS 2.370A NICHICON (Al) UPL1C222MRH 0.028 IRMS 2.010A BVCEO BVCEO SILICONIX NMOS BVDSS RDSON 5.000 NMOS BVDSS RDSON 0.050 CRSS 100pF 32nC NMOS BVDSS RDSON 0.028 CRSS 310pF 69nC
SILICON MOTOROLA SCHOTTKY NP-2A-C1-0R010J COILTRONICS CTX33-10-KM 0.010 Kool CORE
OTHER CAPACITORS CERAMIC QUIESCENT CURRENT 26mA
AN54 F19A
Figure 19A. LTC1149: (12V-48V 5V/10A) High Current, High Voltage Buck Converter
AN54-21
Application Note
LTC1149: (32V-48V 24V/10A) High Current, High Voltage Buck Converter output voltage other than 3.3V required, adjustable version regulator must used. 24V/ example shown Figure 20A. output voltage resistors LTC1149 monitors (pin keeping 1.25V. Similar previous circuits, external gate driver added switch N-channel MOSFET ensure consistent start-up bootstrapping circuitry, driver initially powered (The main requirement start-up supply driver with that exceeds output target voltage.) After switching starts, power external gate drive circuit.
EFFICIENCY
OUTPUT CURRENT (mA)
AN54 F20B
Figure 20B. LTC1149: (32V-48V 24V/10A) High Current, High Voltage Buck Converter Measured Efficiency
IN4148 1N4148
5.1k 1N4148 0.22µF MPS651 1N4148 IRFZ44 50µH MBR160 0.001µF 100pF IRFZ44 220k
1000µF
0.1µF LTC1149 SGND PGND SENSE SENSE NGATE RGND PGATE PDRIVE
2N5087
0.1µF
VN2222LL
1000µF
3300pF
270pF
0.01
(Ta) NICHICON (Al) UPL1J102MRH 0.027 IRMS 2.370A NICHICON (Al) UPL1V102MRH 0.029 IRMS 1.980A NMOS BVDSS RDSON 0.028 CRSS 310pF 69nC BVCEO BVCEO SILICON MOTOROLA SCHOTTKY NP-2A-C1-0R010J COILTRONICS CTX50-10-KM 0.010 Kool CORE
VOUT 1.25V R8/R9) QUIESCENT CURRENT 26mA TRANSITION CURRENT (Burst Mode OPERATION/CONTINUOUS OPERATION) 1.5A
AN54 F20A
OTHER CAPACITORS CERAMIC
Figure 20A. LTC1149: (32V-48V 24V/10A) High Current, High Voltage Buck Converter
AN54-22
Application Note
LT1148: (4V-14V 5V/1A) SEPIC Converter Figure provides function step-up stepdown converter without using transformer. This topology called SEPIC converter. P-channel transistor arranged similarly buck-boost topology providing boost part regulator. Pulses Q2's drain (actually paralleled devices) coupled buck portion that includes This circuit accepts input provides solid output. Even though schematic shows inductors, they carry same current wound single core. Such dual coils readily available (see circuit parts list). This topology acceptable moderate loads only, coupling capacitor carries full load current must sized accordingly. When sense resistor placed ground potential, such case this circuit, off-time increases approximately 40%. adjustable version regulator required when current sense resistor placed ground. This allows provide different output voltages. included foldback short-circuit protection. When VOUT equals zero (output shorted) clamps limits output current.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F21B
Figure 21B. LTC1148: (4V-14V 5V/1A) Buck-Boost Converter Measured Efficiency
Si9430DY 0.1µF PDRIVE LTC1148 SHUTDOWN SENSE 0.1µF 0.082 50µH
220µF
100µF 50µH
VOUT
MBR0520L VOUT 3300pF 390pF
220µF
SGND
SENSE NDRIVE PGND
1N5818 Si9410DY 100pF
(Ta) SANYO (OS-CON) 20SA100M 0.037 IRMS 2.250A SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY NP-1A-C1-0R082J COILTRONICS CTX50-4P, CTX50-5P
VOUT 1.25V R3/R4) QUIESCENT CURRENT 200µA TRANSITION CURRENT (Burst Mode OPERATION/ CONTINUOUS OPERATION) 250mA/VIN
AN54 F21A
OTHER CAPACITORS CERAMIC
Figure 21A. LTC1148: (4V-14V 5V/1A) SEPIC Converter
AN54-23
Application Note
LTC1148: (4V-14V 5V/0.5A, 5V/0.5A) Split Supply Converter Applications requiring split supply circuit presented Figure 22A. contains converter from Figure adds synchronous charge pump provide output. source referenced line, gate drive coupled clamped outputs exhibit excellent tracking with line load changes. This great build dual output converter without transformer.
EFFICIENCY
0.001
0.01 OUTPUT CURRENT
AN54 F22B
Figure 22B. LTC1148: (4V-14V 5V/0.5A, 5V/0.5A) Split Supply Converter Measured Efficiency
Si9430DY 0.1µF PDRIVE SENSE LTC1148 SHUTDOWN SENSE 100pF 0.1µF 0.05 50µH
220µF
100µF +VOUT 0.5A
50µH
MBR0520L VOUT 3300pF 390pF
220µF
SGND
NDRIVE PGND
Si9410DY
1N5818
C10,
0.22µF (Ta) SANYO (OS-CON) 20SA100M 0.037 IRMS 2.250A SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A Si9410DY SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY NP-1A-C1-0R082J COILTRONICS CTX50-4 VOUT 1.25V R3/R4) 1N5818 QUIESCENT CURRENT 250µA TRANSITION CURRENT (DIS/CONT) 130mA/VIN
1N4148
220µF -VOUT 0.5A
AN54 F22A
Figure 22A. LTC1148: (4V-14V 5V/0.5A, 5V/0.5A) Split Supply Converter
AN54-24
Application Note
LTC1148: (4V-10V -5V/1A) Positive-to-Negative Converter Figure shows buck-boost converter using LTC1148. This inverting topology, inherently buck boost input voltage. Ground pins chip referenced output line; additional level shifting circuit required drive N-channel (its source referenced well). even with minimum input level, circuit provides solid peakto-peak MOSFET drive signal. However, exceed absolute maximum voltage input line limited 10V. circuit required accept higher input voltage, LTC1148HV used instead. added provide logic level shutdown feature. shutdown needed omit short
EFFICIENCY
-5V/1A 0.001 0.01 OUTPUT CURRENT
AN54 F23B
-5V/1A
Figure 23B. LTC1148: (4V-10V 5V/1A) Positive-to-Negative Converter Measured Efficiency
Si9430DY
150µF
0.1µF
0.01µF 0.05 1N5818 50µH
SHUTDOWN
TP0610L
PDRIVE SENSE LTC1148 SHUTDOWN SENSE
6800pF 560pF
SGND
NDRIVE PGND
200pF Si9410DY
220µF
(Ta) SANYO (OS-CON) 16SA150M 0.035 IRMS 2.280A SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY NP-1A-C1-0R050J COILTRONICS CTX50-2-MP 0.032 CORE
OTHER CAPACITORS CERAMIC VOUT 1.25V R3/R4)
AN54 F23A
Figure 23A. LTC1148: (4V-10V 5V/1A) Positive-to-Negative Converter
AN54-25
Application Note
LTC1148: (5V-12V 15V/0.5A) Buck-Boost Converter Figure presents inverting regulator designed accommodate higher output voltages. LTC1148 cannot accept feedback directly from negative output. regulate negative outputs, feedback must inverted compared against 1.25V. This function provided level shifting amplifier consisting associated components. Resistor provides amplifier negative feedback, effectively cancelling variations VCC, provides temperature compensation. output voltage resistors usual, with sense resistor ground potential, off-time increases roughly 40%.
EFFICIENCY
0.001 -15V/0.5A -15V/0.5A
0.01 OUTPUT CURRENT
AN54 F24B
Figure 24B. LTC1148: (5V-12V -15V/0.5A) Buck-Boost Converter Measured Efficiency
0.1µF
PDRIVE SENSE SENSE 0.01µF
Si9435DY 50µH
220µF
1.5V SHUTDOWN
SHUTDOWN LTC1148
2N5210 0.033 2N5210 MBR735 200pF
6800pF 200pF
49.9k
SGND
PGND
DALE LVR-3 0.033W COILTRONICS CTX50-5-52 SANYO OS-CON 105A220K SANYO OS-CON 255C47K
47µF
47µF
634k VOUT -15V 0.5A
AN54 F24A
Figure 24A. LTC1148: (5V-12V -15V/0.5A) Buck-Boost Converter
AN54-26
Application Note
LTC1148: (2V-5V 5V/1A) Boost Converter Even though LTC1148 mainly used step-down converters, also show excellent performance boost configuration. boost implementation shown Figure 25A. This two-cell converter that uses LT1109 provide power main regulator chip (unfortunately, MOSFETs operate with only gate). LT1109 small micropower that requires only three external components provides great efficiency. N-channel transistor used switch, general purpose MOSFETs used form inverting gate driver. When turns off, voltage drain rises above VIN, Schottky diode starts conducting. short period time shorts providing synchronous rectification feature increasing efficiency. already available, LT1109 omitted line connected directly
0.05 33µH SHUTDOWN LT1109 SENSE PDRIVE SENSE SHUTDOWN LTC1148 SGND NDRIVE PGND 0.001µF VN2222LL 0.1µF 1N5818
5V/1A
EFFICIENCY
0.001 5V/1A
0.01 OUTPUT CURRENT
AN54 F25B
Figure 25B. LTC1148: (2V-5V 5V/1A) Boost Converter Measured Efficiency
25µH
1N5818
100µF
Si9410
TP0610L Si9410
220µF
SENSE
6800pF 390pF
100pF
SANYO (OS-CON) 10SA100M 0.045 IRMS 1.870A (Ta) SANYO (OS-CON) 10SA220M 0.035 IRMS 2.360A SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY
SL-1-C1-0R050J COILTRONICS CTX33-1 0.220 Kool CORE COILTRONICS CTX25-4
AN54 F25A
VOUT 1.25V R3/R4)
Figure 25A. LTC1148: (2V-5V 5V/1A) Boost Converter
AN54-27
Application Note
LTC1143: (5.2V-14V 3.3V/2A 5V/2A) Dual Buck Converter circuit that provides dual 3.3V/5V output shown Figure 26A. uses dual LTC1143 regulator that combines LTC1147, non-synchronous switching regulators. efficiency measured with only output loaded which provided worse results output current presence second half's quiescent current. This circuit provides very simple means power dual voltage logic. occupies small amount board space very efficient!
EFFICIENCY
0.001 3.3V
3.3V
0.01 OUTPUT CURRENT
AN54 F26B
Figure 26B. LTC1143: (5.2V-14V 3.3V/2A 5V/2A) Dual Buck Converter Measured Efficiency
5.2V
CIN3 22µF 20µH
0.22µF P-CH Si9430DY 0.01µF SENSE VIN3 PDRIVE3 SENSE LTC1143 SENSE NORMAL >1.5V SHUTDOWN SHUTDOWN SHUTDOWN 0.22µF VIN5 PDRIVE5 SENSE 0.01µF P-CH Si9430DY
CIN5 22µF 20µH
VOUT3 3.3V/2A
RSENSE3 0.05
RSENSE5 0.05
VOUT5 5V/2A
COUT3 220µF
MBRD330
GND3
ITH3
ITH5
GND5
MBRD330
COUT5 220µF
SL-1R050J RSENSE: COILTRONICS CTX20-4 (Ta) TPSD226K025R0200 CIN3, CIN5: COUT3, COUT5: (Ta) TPSE227K010R0080 SILICONIX PMOS Si9430DY
390pF
3300pF
3300pF
200pF
AN54 F26A
Figure 26A. LTC1143: (5.2V-14V 3.3V/2A 5V/2A) Dual Buck Converter
AN54-28
Application Note
LTC1148HV-5: (5.2V-18V 5V/1A) High Voltage Buck Converter standard LTC1148 input voltage limited absolute maximum level, which sufficient some applications. Figure shows step-down regulator using high voltage LTC1148HV. contains same internal functions accepts input (remember, MOSFET's gates usually rated maximum). building block used same manner LTC1148. Input tantalum capacitors have rated ensure reliable operation under maximum input voltage.
EFFICIENCY
0.001 0.01 OUTPUT CURRENT
AN54 F27B
Figure 27B. LTC1148HV-5: (5.2V-18V 5V/1A) High Voltage Buck Converter Measured Efficiency
5.2V
Si9430DY
MBRS140T3
10µF
Si9410DY
PDRIVE
NDRIVE
1000pF VOUT 5V/1A SHUTDOWN COUT 220µF 50µH
220pF
SENSE
SENSE
COUT
(Ta) TPSD106K035R0300 (Ta) TPSE227K010R0080 COILTRONICS CTX50-4 SP-1/2-A1-0R100 SILICONIX PMOS Si9430DY SILICONIX NMOS Si9410DY
Figure 27A. LTC1148HV-5: (5.2V-18V 5V/1A) High Voltage Buck Converter
LTC1148HV-5 PGND SGND
3300pF
SHUTDOWN
AN54 F27A
AN54-29
Application Note
LTC1148HV-3.3 (4V-18V 3.3V/1A) High Voltage Buck Converter
EFFICIENCY
0.001 0.01 OUTPUT CURRENT
AN54 F28B
3.3V
Figure 28A: Here high voltage version circuit shown Figure with input voltage increased 18V.
3.3V
3.3V
Figure 28B. LTC1148HV-3.3: (4V-18V 3.3V/1A) High Voltage Buck Converter Measured Efficiency
Si9430DY
MBRS140T3
22µF
Si9410DY
PDRIVE
NDRIVE
1000pF VOUT 3.3V/1A SHUTDOWN COUT 220µF 50µH
270pF
SENSE
SENSE
COUT
(Ta) TPSE226K035R0300 (Ta) TPSE227K010R0080 COILTRONICS CTX50-4 Kool CORE LR2010-01-R100-G SILICONIX PMOS Si9430DY SILICONIX NMOS Si9410DY
Figure 28A. LTC1148HV-3.3: (4V-18V 3.3V/1A) High Voltage Buck Converter
AN54-30
LTC1148HV-3.3 PGND SGND
3300pF
SHUTDOWN
AN54 F28A
Application Note
LTC1148HV: (12.5V-18V 12V/2A) High Voltage Buck Converter Figure another application LTC1148HV which configured step-down converter provide 12V/2A output. With this dropout regulator, input 12.5V still produce regulated output. Resistors output voltage level.
EFFICIENCY
0.001 0.01 OUTPUT CURRENT
AN54 F29B
Figure 29B. LTC1148HV: (16V 12V/2A) High Voltage Buck Converter Measured Efficiency
12.5V
0.1µF PDRIVE SHUTDOWN LTC1148HV SENSE SENSE 0.01µF Si9430DY
22µF
47µH
0.05
3300pF
150pF
NDRIVE SGND PGND
Si9410DY 100pF MBRS140T3
432k 49.9k
150µF
(Ta) SANYO (OS-CON) 16SA150M SILICONIX PMOS BVDSS RDSON 0.100 CRSS 400pF 50nC SILICONIX NMOS BVDSS RDSON 0.050 CRSS 160pF 30nC MOTOROLA SCHOTTKY SL-1-C1-0R050J COILTRONICS CTX47-5P
AN54 F29A
Figure 29A. LTC1148HV: (12.5V-18V 12V/2A) High Voltage Buck Converter
AN54-31
+VIN 6.5V Si9410DY MBRS140 Si9430DY 22µF
AN54-32
22µF
SHUTDOWN (TTL INPUT) 33µH CTX33-4
3300pF Si9430DY
VIN5 SHUTDOWN3 ITH3 VCC3 2200pF
22µF 1000pF 22µF
Si9410DY MBRS140
0.050
Application Note
100µF
SHUTDOWN (TTL INPUT) 1000pF 30µH, LPE-6562-A026 0.040 0.1µF 1.8T MBRS140
100µF
3.3V/2A
3300pF
VIN3 PDRIVE3 NDRIVE3 SENSE+3 SENSE PDRIVE5 LTC1142 NDRIVE5 SHUTDOWN5 SENSE ITH5 SENSE INTV PGND3 PGND5 SGND3 SGND5
390pF
200pF
220µF
220µF
5V/2A
-VIN
ENABLE VN7002
SHDN
VOUT LT1121CS8
20pF 294k 649k
22µF
22µF 12V/150mA
MAX) FLOAT
AN54 F30A
C11, C20,
(Ta) TPSD226M025R0200 (Ta) TPSD107K010R0100 (Ta) TPSE227M010R0100 COILTRONICS CTX33-4
LR2512-R050 LR2512-R040 DALE, LPE-6562-AO26
SHUTDOWN PINS MUST ACTIVELY DRIVEN EITHER HIGH ALLOWED FLOAT.
Figure 30A. LTC1142: (6.5V-14V 3.3V/2A, 5V/2A, 12V/0.15A) Triple Output Buck Converter
Application Note
LTC1142: (6.5V-14V 3.3V/2A, 5V/2A, 12V/0.15A) Triple Output Buck Converter LTC1142 dual output synchronous switching regulator controller. independent controller blocks (LTC1148-based) simultaneously provide 3.3V outputs. circuit Figure shows application this generates triple output voltages with flash memory programming addition usual logic power levels. 3.3V section regular buck converter circuit, section contains off-the-shelf transformer place inductor. secondary winding used boost output level which rectified regulated LT1121 provide clean stable output. turns ratio 1:1.8 used ensure that input voltage LT1121 high enough keep regulator dropout. With LTC1142 synchronous switching, auxiliary output loaded without regard primary output load long loop remains continuous operation mode. Continuous operation ensured which inhibits Burst Mode whenever output enabled (enable line goes high). Make sure that enable lines floating driven level signals. circuit board been laid this circuit subsequently been thoroughly tested under full operating conditions optimized mass production requirements. Gerber file board available upon request.
EFFICIENCY 0.001 0.01 OUTPUT CURRENT LTC1142-3.3 LTC1142-5
AN54 F30B
Figure 30B. LTC1142:(6.5V-14V 3.3V/2A, 5V/2A, 12V/0.15A) Triple Output Buck Converter Measured Efficiency
AN54-33
Application Note
LTC1142HV: (6.5V-18V 3.3V/2A, 5V/2A, 12V/0.15A) High Voltage Triple Output Buck Converter
EFFICIENCY 0.001 0.01 OUTPUT CURRENT LTC1142-3.3 LTC1142-5
Figure shows same configuration Figure using high voltage LTC1142HV. Circuit operation identical, accept input.
AN54 F30B
Figure 31B. LTC1142HV: (6.5V-18V 3.3V/2A, 5V/2A, 12V/0.15A) Measured Efficiency
6.5V
22µF
Si9430DY
VIN3 PDRIVE3 SENSE
NORMAL >1.5V SHUTDOWN SHUTDOWN SHUTDOWN VIN5
PDRIVE5 SENSE 1000pF SENSE NDRIVE5
Si9430DY
22µF 1.8T 30µH RSENSE5 0.04
VOUT3 3.3V/2A
RSENSE3 0.05
33µH
2000pF
VOUT5 5V/2A
LTC1142HV SENSE NDRIVE3 PGND3 SGND3 ITH3 ITH5 SGND5
220µF
MBRS140
Si9410DY
MBRS140 Si9410DY VN7002
100µF
PGND5
3300pF 3300pF 390pF 200pF ENABLE MAX) 20pF 660k 300k VOUT SHUTDOWN LT1121 MBRS140 1000pF
RSENSE3 RSENSE5
(Ta) TPS226K035R0300 (Ta) TPSD227K010R0100 COILTRONICS CTX33-4 SL-C1-1/2-0R050J SL-C1-1/2-0R040J DALE LPE-6562-A026 PRIMARY: SECONDARY 1:1.8
22µF
Figure 31A. LTC1142HV: (6.5V-18V 3.3V/2A, 5V/2A, 12V/0.15A) High Voltage Triple Output Buck Converter
AN54-34
12V/150mA
22µF
Application Note
LTC1148: High Efficiency Charger Circuit LTC1148 regulator used highly efficient battery charging device. Figure shows circuit that programmable 1.3A fast charge 100mA trickle charge mode. During fast charge interval, resistor divider network forces LTC1148 feedback below 1.25V causing regulator operate maximum output current. Sense resistor controls current approximately 1.3A. When batteries disconnected, error amplifier sets output voltage 8.1V (for proper operation this voltage should exceed maximum possible voltage across battery pack). Diode prevents batteries from discharging through divider network when charger shut down. Dual rate charging controlled which selects between fast trickle charge. When transistor turns limits error amplifier output that current limiter starts operating 100mA. trickle charge current needs altered, adjust With 1.3A output current, this charger capable efficiency excess which minimizes power dissipated surface mount components.
0.1µF PDRIVE SHUTDOWN SENSE LTC1148 SENSE 0.01µF Si9430DY
22µF 50µH
NORMAL 1.5A SHUTDOWN
MBRS340T3 VOUT
VBAT CELLS 274k Si9410DY MBRS140T3 49.9k
3300pF
200pF
NDRIVE SGND PGND
100pF
220µF
TRICKLE CHARGE
VN2222LL
(Ta) (Ta) TPSD226K025R0100 0.100 0.775A (Ta) TPSE227M010R0100 0.100I 1.149A SILICONIX PMOS RDSON 0.125 CRSS 400pF 25nC 50°C/W SILICONIX NMOS RDSON 0.050 CRSS 160pF 50nC 50°C/W MOTOROLA SCHOTTKY SP-1/2-A1-0R100J 0.75V COILTRONICS CTX50-4 0.175 1.350A Kool CORE OTHER CAPACITORS CERAMIC
VOUT 1.25V R4/R5) 8.1V FAST CHARGE 130mV/R3 1.3A TRICKLE CHARGE 100mA EFFICIENCY
AN54
Figure LTC1148: High Efficiency Charger Circuit
AN54-35
Application Note
LTC1148: High Voltage Charger Circuit Figure variation Figure designed charge cells uses LTC1148HV higher input voltages. value been changed provide 12.3V output when battery connected.
0.1µF PDRIVE SHUTDOWN SENSE LTC1148HV SENSE 0.01µF Si9430DY
22µF 50µH
NORMAL 1.5A SHUTDOWN
MBRS340T3 VOUT
VBAT CELLS 442k Si9410DY MBRS140T3 49.9k
3300pF
200pF
NDRIVE SGND PGND
100pF
100µF
TRICKLE CHARGE
VN2222LL
(Ta) (Ta) TPSD226K035R0200 0.200 0.663A (Ta) TPSE107M016R0100 0.100I 1.149A SILICONIX PMOS RDSON 0.125 CRSS 400pF 25nC 50°C/W SILICONIX NMOS RDSON 0.050 CRSS 160pF 50nC 50°C/W MOTOROLA SCHOTTKY SP-1/2-A1-0R100J 0.75V COILTRONICS CTX50-4 0.175 1.350A Kool CORE OTHER CAPACITORS CERAMIC
VOUT 1.25V R4/R5) 12.3V FAST CHARGE 120mV/R3 1.3A TRICKLE CHARGE 100mA EFFICIENCY
AN54
Figure LTC1148: High Voltage Charger Circuit
AN54-36
Application Note
LTC1142A: High Efficiency Power Supply Providing 3.3V/2A with Built-In Battery Charger Figure implements high efficiency step-down converter with built-in battery charger using single section dual LTC1142A used convert 4-cells 3.3V/2A regular buck configuration. other section configured same battery charger from Figure powered from wall adapter provides battery with fast trickle charging rate. When adapter connected, prevents battery from discharging through R2/R1 divider network.
FROM WALL ADAPTER
CHARGE >1.5V CHARGE
OUTPUT >1.5V 3.3V OUTPUT
MBRS340T3 50µH
CIN1 22µF 0.22µF P-CH Si9430DY 1000pF VIN1 PDRIVE1 SENSE SENSE VFB1 NDRIVE1 PGND1 SGND1 ITH1 ITH2 3300pF 330pF 100pF LTC1142A SHUTDOWN SHUTDOWN VIN2 PDRIVE2 SENSE SENSE VFB2 NDRIVE2 SGND2 PGND2 1000pF N-CH Si9410DY MBRS140T3 0.22µF P-CH Si9433DY 25µH
CIN2 22µF
VBATT CELLS NiCAD
RSENSE1
RSENSE2 0.05
VOUT2 3.3V/2A
COUT1 220µF
MBRS140T3 N-CH Si9410DY
84.5k
274k 49.9k
COUT2 220µF
100pF
200pF VN2222LL
3300pF
RSENSE1 RSENSE2
COILTRONICS CTX50-4 COILTRONICS CTX25-4 SL-C1-1/2-1R100J SL-C1-1/2-1R050J
TRICKLE CHARGE
FAST CHARGE 130mV/RSENSE1 1.3A TRICKLE CHARGE 130mV/RSENSE1 100mA
AN54
Figure LTC1142A: High Efficiency Power Supply Providing 3.3V/2A with Built-In Battery Charger
AN54-37
Application Note
LTC1149: Dual Output Buck Converter circuit shown Figure implements most elegant approach dual output regulators that provide 3.3V outputs. uses single LTC1149. synchronous rectification feature this chip used provide excellent efficiency, well good cross regulation between outputs. Maximum output power converter 17W, which drawn combination between 3.3V outputs. regular buck regulator used producing 3.3V output with T1's primary place buck inductor. secondary forms boost winding output. transformer wound with simple trifilar winding ensure that primary closely coupled secondary. Superior cross regulation achieved close primary-to-secondary coupling splitting voltage feedback paths (resistors provide feedback signals from both 3.3V outputs). Diodes capacitor comprise soft-start circuit that causes output voltage increase slowly when power first applied circuit. This circuit prevents overshoot 3.3V output. transformer used this example standard product (see parts list). circuit board been laid this circuit subsequently been thoroughly tested under full operating conditions optimized mass production requirements. Gerber file board available upon request.
EFFICIENCY
TOTAL POWER OUTPUT
AN54 F35B
Figure 35B. LTC1149: Dual Output Buck Converter Measured Efficiency
BOLD LINES INDICATE HIGH CURRENT PATHS (SHORT LEADS)
22µF
22µF
22µF
22µF 0.1µF S/D1/VFB S/D2 PDRIVE PGATE
BAS16
Si9435DY
Si9435DY
HL-8700
0.047µF 1000pF
MBRS140 Si9410DY
220µF
2200pF
1000pF
0.068µF 2.2µF 24.9k 56pF
LTC1149 NGATE VO(REG) SENSE VI(REG) SENSE PGND RGND SGND
220µF
0.02 BAS16
3.3V
220µF MBRS140
220µF 220µF
BAS16 Si9410DY 10µF
220µF
102k
BAS16
124k
VOUT -VIN C15, (Ta) TPSE227M010R 49BCPA (Ta) TPSE226M035R 49BCPA LR512-01-R020F HURRICANE, HL-8700
AN54 F35A
Figure 35A. Single LTC1149: Dual Output Buck Converter
AN54-38
Application Note
LTC1148: Constant Frequency Buck Converters Finally, Figures show circuits that completely satisfy demand ultra-high efficiency converters operating synchronously with external clock. rising edge clock saturates pulling below internal comparator threshold. internal logic assumes off-time, turns LTC1148 operates conventional constant frequency current mode controller therefore requires slope compensation. generates artificial ramp signal that superimposed inductor current waveform sensed shunt This standard technique eliminate subharmonic oscillation, phenomenon that occurs under simultaneous conditions fixed frequency fixed amplitude inductor current when duty cycle exceeds 50%. Subharmonic oscillations related closed-loop transfer function.
EFFICIENCY
OUTPUT CURRENT
AN54 F36B
Figure 36B. LTC1148: (8V-15V 5V/2A) Constant Frequency Buck Converter Measured Efficiency
0.1µF
510k
PDRIVE SENSE SENSE Si9430DY
22µF
1.5V SHUTDOWN
SHUTDOWN LTC1148-5
1000pF
15µH 0.04
6800pF 1N4148 51pF 200kHz 2N2222 200pF
NDRIVE
Si9410DY MBR130T3
220µF
VOUT
SGND
PGND
1N4148 2N2222 1N4148 5.1k 100pF
OPERATION BEYOND SPECIFIED INPUT VOLTAGE CAUSE INSTABILITY. EXTERNAL OSCILLATOR INPUT: LEVEL. APPLICATIONS WITH 2VOUT SLOPE COMPENSATION DELETED. (Ta) TPSD226K025R0200 (Ta) TPSE227K010R0080 COILTRONICS CTX15-4 SL-1-C1-0R040J
SLOPE COMPENSATION
AN54 F36A
Figure 36A. LTC1148: (8V-15V 5V/2A) Constant Frequency Buck Converter
AN54-39
Application Note
input voltage always exceeds twice output (duty cycle this case would less than 50%) circuit inside dashed omitted. Resistor added circuit disable Burst Mode operation ensuring true in-sync operation over full range output current. circuitry designed synchronized 200kHz clock accommodate other external frequencies; nothing more than component value changes required. input voltage goes beyond specified range, controller will lose synchronization will still regulate, however). increases input voltage pull-in range omitted required. Values above 430k ensure proper start-up.
EFFICIENCY
4.5V 3.3V/2A
6.5V 3.3V/2A OUTPUT CURRENT
AN54 F37B
Figure 37B. LTC1148: (4.5V-6.5V 3.3V/2A) Constant Frequency Buck Converter Measured Efficiency
4.5V 6.5V
0.1µF
470k
PDRIVE SENSE Si9430DY
22µF
1.5V SHUTDOWN
SHUTDOWN
1000pF
15µH 0.04
3300pF 1N4148 50pF 200kHz 150pF
LTC1148-3.3 SENSE
NDRIVE
Si9410DY MBR130T3
220µF
VOUT 3.3V
SGND
PGND
1N4148 2N2222 1N4148 2.2k 100pF
2N2222
OPERATION BEYOND SPECIFIED INPUT VOLTAGE CAUSE INSTABILITY. EXTERNAL OSCILLATOR INPUT: LEVEL. (Ta) TPSD226K025R0200 (Ta) TPSE227K010R0080 COILTRONICS CTX15-4 SL-1-C1-R040J
SLOPE COMPENSATION
AN54 F37A
Figure 37A. LTC1148: (4.5V-6.5V 3.3V/2A) Constant Frequency Buck Converter
AN54-40
Application Note
APPENDIX TOPICS COMMON INTEREST Defeating Bust Mode Operation Sometimes applications require Burst Mode operation defeated. might useful high output current circuit which never operates light loads. Ensuring continuous operation this case usually improves circuit noise immunity helps eliminate audible noise from certain types inductors when they lighter loaded. Burst Mode operation should disabled overwinding used provide boosted voltage, additional main output (for example, Figure 30A). This allows draw power from secondary with improved cross-regulation, even primary output loaded. Defeating Burst Mode operation should also considered when fixed frequency circuits from Figures used. With continuous operation these circuits always operate fully synchronized external clock. Whatever reason, Burst Mode operation suppressed with simple external network which cancels 25mV minimum current comparator threshold. external offset series with SENSE subtract from built-in 25mV offset. example this technique shown Figure
33µH LTC1148 FAMILY SENSE
VOFFSET exceeds 25mV minimum threshold will cancelled Burst Mode operation prevented from occurring. Since offset voltage constant, maximum load current also decreased. Thus back same output current, sense resistor must lower:
RSENSE
75mV IMAX
Soft-Start Circuits Right after power-on, regulator operates shortcircuit condition while charging output capacitors. With earlier voltage mode converters, this enormous current transient start-up. Soft-start circuits were usually added this problem. LTC1148 series implements current mode technique which inherently provides current limiting does require special soft-start circuits. Start-up current limited shortcircuit current value 150mV/RSENSE. Some applications might, however, require softer start. helps avoid output overshoot when power first applied circuit, also prevents input supply's overcurrent protection from latching, when input voltage increases slowly. Figures provide possible solutions soft-start. Capacitor Figure holds down limiting output current. charged when voltage across terminals exceeds level pin, becomes reverse-biased capacitor longer effect circuit operation. provides discharge path when input voltage removed. soft-start time constant defined Figure capacitor holds down SENSE providing additional offset current comparator. charges through slowly increasing maximum operating current. When fully charged reversebiased capacitor longer affects operation.
RSENSE 0.05
100pF
VOUT
SENSE
AN54 FA01
Figure Defeating Burst Mode
resistors inserted series with leads from sense resistor. With addition current generated through causing offset VOFFSET VOUT
AN54-41
Application Note
provides discharge path when output voltage disappears. soft-start time constant defined
1N4148 MBR0520L
LTC1148 FAMILY
4.7µF
3300pF
simplest approach uses load step transient switching additional load resistor simultaneously monitoring output. Switching regulators take several cycles respond step resistive load current. When load step occurs, output voltage shifts amount equal ILOAD ESR, where output capacitor effective series resistance. Load current change also begins charge discharge output capacitor until regulator loop adapts current change returns VOUT steady state value. during this recovery time VOUT ringing, indicates stability problem, capacitor should increased. simple dynamic load circuit shown Figure where MOSFET driven external generator, switches load resistor out. generator should provide gate drive (not level). drive signal frequency critical. good starting point 500Hz load change from full load.
AN54 FA02
Figure Soft-Start Circuit with Clamping
33µH LTC1148 FAMILY SENSE
RSENSE 0.05
1000pF 1N4148
VOUT
SENSE
LTC1148 FAMILY
COUT
1N4148
10µF
AN54 FA03
GENERATOR (10VP-P) 100k
IRFZ44 (HEAD SINK REQUIRED)
AN54 FA04
Figure Soft-Start Circuit with Sense Clamping Figure Simple Dynamic Load
Frequency Compensation LTC1148 family regulators contains both voltage current loops, which, together with external capacitors inductors, require pretty complex mathematical approach frequency compensation. Operating point changes with input voltage output current variations complications suggest more practical empirical method. LTC1148 series regulators provide very stable operation. compensation values used circuits this note have been tested over wide range operating conditions proved provide adequate compensation most applications. Usually stability testing, described above, required.
AN54-42
Application Note
APPENDIX SUGGESTED MANUFACTURERS Linear Technology provides this list manufacturers started your component selection process. make claims about these companies except that they provide components necessary switching power supplies. There many more companies choose from; more complete list refer PCIM Buyer's
Batteries Duracell Sales Marketing Berkshire Industrial Park Bethel, 06801 (800) 431-2656 Eveready Battery Checkerboard Square Louis, 63164 (314) 982-2000 Bipolar Transistors Motorola Inc. 3102 North 56th 56-126 Phoenix, 85018 (800) 521-6274 Full Line Zetex Modular Ave. Commack, 11725 (516) 543-7100 High Gain Bipolar Switching Transistors including Surface Mount Devices Capacitors Corporation P.O. Myrtle Beach, 29578 (803) 946-0690 Tant., Cer., Surface Mount Elpac 1567 Reynolds Ave. Irvine, 92714 Film Capacitors (714) 476-6070 Film Capacitors Intertechnical Group 2269 Mill River Rd., Bldg. P.O. Elmsford, 10523 (914) 347-2474 Polycarbonate Film Philips Components 1440 Indian Town Jupiter, 33458 (407) 744-4200 Cer., Chip Capacitors Murata Erie North America 1900 College Ave. State College, 16801 (814) 237-1431 Nichicon (America) Corporation East State Parkway Schaumburg, 60173 (708) 843-7500 Aluminum Electrolytic Sanyo Video Components (USA) Corp. 2001 Sanyo Ave. Diego, 92173 (619) 661-6835 Filter Capacitors-Solid Aluminum Electrolytic Capacitors (OS-CON) Sprague Main P.O. Sanford, 04073 (207) 324-4140 Tantalum Capacitors Current Sense Resistors Dale Electronics 1122 23rd P.O.Box Columbus, 68602 (402) 564-3131 Resistors, Inductors, Xformers 4222 South Staples Corpus Christi, 78411 (512) 992-7900 Bouchard Manchester, 03103 (603) 668-3210
Guide. PCIM (Power Conversion Intelligent Motion) published Intertec International Inc., 2472 Eastman Ave., Bldg. 33-34, Ventura, California 93003-5774, (805) 650-7070. PCIM free qualified applicants. Back issues, such Buyer's Guide purchased.
Diodes Fuji/Collmer 14368 Proton Dallas, 75244 (214) 233-1589 Current Schottkys General Instruments Melville Park Melville, 11747 (516) 847-3222 Motorola Inc. 5005 McDowell P.O. 2953 Phoenix, 85062 (602) 244-5768 Diodes Philips Components Disc. Prod. Div. Providence Pike Slatersville, 02876 (401) 762-3800 Discrete Semi Group Ferrite Beads Fair-Rite Products Corp. Commerial P.O. Wallkill, 12589 (914) 895-2055 Toshiba America Elec. Components 9775 Toledo Irvine, 92718 (714) 455-2000 Heat Sinks Aavid Engineering, Inc. Kool Path Laconia, 03247 (603) 528-3400 Int'l Electronic Research Group Magnolia Blvd. Burbank, 91502 (213) 849-2481
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
AN54-43
Application Note
Thermalloy 2021 Valley View Lane Dallas, 75234 (214) 243-4321 Inductors Transformers Beckman Industrial Corp. 4200 Bonita Place Fullerton, 92635 (714) 447-2345 Inductors, Xformers including Caddell-Burns East Second Mineola, 11501 (516) 746-2310 Coilcraft 1102 Silver Lake Cary, 60013 (800) 322-2645 Coiltronics 6000 Park Commerce Blvd. Boca Raton, 33487 (407) 241-7876 Full Line including Surface Mount Inductors Dale Electronics Highway Yankton, 57078 (605) 665-9301 Inductors, Xformers including Gowanda Electronics Corp. Industrial Place Gowanda, 14070 (716) 532-2234 Hurricane Electronics P.O. 1280 Hurricane, 84737 (801) 635-2003 Murata Erie North America 2200 Lake Park Drive Smyrna, 30080 (404) 436-1300 Renco Jefryn Blvd. Deerpark, 11729 (516) 586-5566 Sumida Electronic 5999 Wilke Rd., Ste. Rolling Meadows, 60008 (708) 956-0666 Corp. America 1600 Feehanville Mount Prospect, 60056 (708) 803-6100 Toko America Incorporated 1250 Feehanville Mount Propsect, 60056 (708) 635-3200 Magnetic Materials Fair-Rite Products Corp. Commercial Wallkill, 12589 (914) 895-2055 Ferrite Micrometals, Inc. 1190 Hawk Circle Anaheim, 92807 (800) 356-5977 Powdered Iron Magnetics Div. Spang P.O. Butler, 16003-0391 (412) 282-8282 Molypermalloy, Kool Ferrite Philips Components Disc. Prod. Div. Materials Group 1033 King Highway Saugerties, 12477 (914) 246-2811 Ferrite Pyroferric International, Inc. Madison Toledo, 62468 (217) 849-3300 Powdered Iron Siemens Components, Inc. Wood Ave. South Iselin, 08830 (908) 906-4300 Ferrite Corp. America 1600 Feehanville Mount Prospect, 60056 (708) 803-6100 Ferrite Mounting Hardware Bergquist 5300 Edina Industrial Blvd. Minneapolis, 55439 (612) 835-2322 Thermally Conductive Insulators Stockwell Rubber 4749 Tolbut Philadelphia, 19136 (800) 523-0123 Thermally Conductive Insulators Thermalloy 2021 Valley View Lane Dallas, 75234 (214) 243-4321 Power Sockets, Thermal Compounds, Adhesives Thermally Conductive Insulators, Mounting Kits Power MOSFETs International Rectifier Corp. Kansas Segundo, 90245 (310) 322-3331 Motorola Inc. 5005 McDowell Phoenix, 85008 (602) 244-3576 Siliconix 2201 Laurelwood Santa Clara, 96056 (800) 554-5565 Resistors Micro-Ohm Corp. 1088 Hamilton Duarte, 91010 (818) 357-5377 Thermo Disc 1981 Port City Blvd. Muskegon, 49443 (616) 777-2602 Components, Inc. East Industrial Park Manchester, 03109 (603) 669-0054 Caddock Electronics 1717 Chicago Ave. Riverside, 92507-2364 (909) 788-1700 Wire Belden Wire Cable P.O. 1980 Richmond, 47375 (317) 983-5200
AN54-44
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7487
(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977
LT/GP 1094 PRINTED
LINEAR TECHNOLOGY CORPORATION 1993

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