Constant On-Time Buck Controller Hyper Speed ControlFamily Micrel

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Constant On-Time Buck Controller Hyper Speed ControlFamily Micrel

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MIC2164/-2/-3
Constant On-Time Buck Controller Hyper Speed ControlFamily
Micrel MIC2164/-2/-3 synchronous, digital modified, constant on-time pulse-width modulation (PWM) buck controller family. MIC2164 first product Hyper Speed Controlfamily buck controllers introduced Micrel. These controllers targeted cost sensitive applications requiring high performance such set-top boxes, gateways, routers, computing peripherals, telecom/networking equipments. MIC2164/-2/-3 family operates over input supply range 28V, independent supply voltage. MIC2164/-2/-3 family capable supplying output current. MIC2164 operates 300kHz, MIC2164-2 operates 600kHz, MIC2164-3 operates 1MHz. unique Hyper Speed Controlarchitecture allows ultra-fast transient response while reducing output capacitance also makes High VIN/Low VOUT operation possible. MIC2164/-2/-3 family utilizes architecture which constant ripple controlled. UVLO feature provided ensure proper operation under power-sag conditions prevent external power MOSFET from overheating. soft start feature provided reduce inrush current. Foldback current limit "hiccup" mode short-circuit protection ensure load protection. MIC2164/-2/-3 family available 10-pin MSOP (MAX1954A-compatible) package with junction operating range from -40°C +125°C. support documentation found Micrel's site www.micrel.com.
Features
Hyper Speed Controlarchitecture enables High delta operation (VIN=28V VOUT=0.8V) Smaller output capacitors than competitors input voltage output current capability 300kHz/600kHz/1MHz switching frequency Constant on-time mode control Output down 0.8V with accuracy efficiency Simple Foldback current limit "hiccup" mode short-circuit protection N-Channel MOSFET design current-sense resistor needed Internal soft start Thermal shutdown Pre-bias output safe -40°C +125°C junction temperature range Available 10-pin MSOP (MAX1954A compatible) package Wide input power supply Set-top box, gateways routers Printers scanners Graphic cards video cards servers Microprocessor core supply Low-voltage distributed power Telecommunication networking
Applications
MicroLeadFrame registered trademarks Amkor Technology, Inc. Micrel Inc. 2180 Fortune Drive Jose, 95131 (408) 944-0800 (408) 474-1000 http://www.micrel.com
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Typical Application
MIC2164 3.3V Efficiency
EFFICIENCY
VIN=5V
MIC2164/-2/-3 Adjustable Output 300kHz/600kHz/1MHz Buck Converter
OUTPUT CURRENT
Ordering Information
Part Number MIC2164YMM MIC2164-2YMM MIC2164-3YMM Voltage Adj. Adj. Adj. Switching Frequency 300kHz 600kHz 1MHz Junction Temp. Range -40° +125°C -40° +125°C -40° +125°C Package 10-pin MSOP 10-pin MSOP 10-pin MSOP Lead Finish Pb-Free Pb-Free Pb-Free
Configuration
10-Pin MSOP (MM)
Description
Number Name Function High-Side N-MOSFET Drain Connection (input): Power drain external high-side N-channel MOSFET. operating voltage range from 28V. Input capacitors between power ground (PGND) required. Enable (input): logic level control output. CMOS-compatible. Logic high floating enable, logic shutdown. state, supply current device greatly reduced (typically 0.8mA). Feedback (input): Input transconductance amplifier control loop. regulated 0.8V. resistor divider connecting feedback output used adjust desired output voltage. Signal ground. ground path device input voltage control circuitry. loop signal ground should separate from power ground (PGND) loop. Input Voltage (input): Power internal reference control sections MIC2164/-2/-3. operating voltage range from 5.5V. 0.1µF ceramic capacitors from recommended clean operation.
June 2009
M9999-061209-A
Micrel, Inc.
PGND
MIC2164/-2/-3
Low-Side Drive (output): High-current driver output external low-side MOSFET. driving voltage swings from ground-to-IN. Power Ground. PGND ground path MIC2164/-2/-3 buck converter power stage. PGND connects sources low-side N-Channel MOSFETs, negative terminals input capacitors, negative terminals output capacitors. loop power ground should small possible separate from Signal ground (GND) loop. High-Side Drive (output): High-current driver output external high-side MOSFET. driving voltage floating switch node voltage (LX). swings from ground minus diode drop. Adding small resistor between gate high-side N-channel MOSFETs slow down turn-on turn-off time MOSFETs. Switch Node Current Sense input: High current output driver return. connects directly switch node. high speed switching this pin, should routed away from sensitive nodes. also senses current monitoring voltage across low-side MOSFET during time. order sense current accurately, connect low-side MOSFET drain using Kelvin connection.
Boost (output): Bootstrapped voltage high-side N-channel MOSFET driver. Schottky diode connected between pin. boost capacitor 0.1F connected between pin. Adding small resistor series with boost capacitor slow down turn-on time high-side N-Channel MOSFETs.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Absolute Maximum Ratings(1)
-0.3V -0.3V -0.3V +37V LX.-0.3V (VBST 0.3V) COMP GND.-0.3V (VIN 0.3V) GND. -0.3V PGND -0.3V +0.3V Junction Temperature +150°C Storage Temperature (TS).-65°C +150°C Lead Temperature (soldering, 10sec). 260°C
Operating Ratings(2)
Input Voltage (VIN). 3.0V 5.5V Supply Voltage (VHSD) 3.0V Operating Temperature Range .-40°C +125°C Junction Temperature (TJ) .-40°C +125°C Junction Thermal Resistance MSOP (JA) .130.5°C/W Continuous Power Dissipation 70°C).421mW (derate 5.6mW/°C above 70°C)
Electrical Characteristics(4)
VBST 25°C, unless noted. Bold values indicate -40°C +125°C.
Parameter General Operating Input Voltage (VIN) Voltage Range (VHSD) Quiescent Supply Current Standby Supply Current Under-voltage Lockout Trip Level UVLO Hysteresis DC-DC Controller Output-Voltage Adjust Range (VOUT) Error Amplifier Regulation Voltage Regulation Voltage Input Leakage Current Current-Limit Threshold 0.8V Soft-Start Soft-start Period
Notes: Exceeding absolute maximum rating damage device. device guaranteed function outside operating rating. Devices sensitive. Handling precautions recommended. Human body model, 1.5k series with 100pF. Specification packaged product only. application fully functional (supply control section) external MOSFETs have enough voltage VTH. current will come only from internal 100k pull-up resistor sitting Input tied maximum VOUT value limited Fixed estimator which obtains VOUT divided value (1/6).
Condition
Units
Mode: (VFB 1.5V, output switching excluding external MOSFET gate current) VBST 5.5V, VHSD unconnected,
85°C -40°C 125°C
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Parameter Oscillator Switching Frequency
Condition MIC2164 MIC2164-2 MIC2164-3
0.225 0.45 0.75
0.375 0.75 1.25
Units
Maximum Duty Cycle
MIC2164 MIC2164-2 MIC2164-3
Minimum Duty Cycle Drives Output Voltage Output High Voltage
Measured
ISINK 10mA ISOURCE 10mA VIN-0.1V VBST-0.1V 28V, 5.5V,VBST 33.5V 28V, 5.5V,VBST 33.5V
On-Resistance, High State On-Resistance, State On-Resistance, High State On-Resistance, State Leakage Current Leakage Current Thermal Protection Over-temperature Shutdown Over-temperature Shutdown Hysteresis Shutdown Control Logic Level Logic Level High Pull-up Current
Note: Measured test mode. Measured maximum duty cycle limited fixed mandatory time Toff typical 363ns.
<5.5V <5.5V
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Typical Characteristics
MIC2164 1.5V Efficiency
MIC2164 3.3V Efficiency
MIC2164-2 1.5V Efficiency
EFFICIENCY
EFFICIENCY
EFFICIENCY VIN=5V
VIN=5V
VIN=5V
OUTPUT CURRENT
OUTPUT CURRENT
OUTPUT CURRENT
MIC2164-2 3.3V Efficiency
MIC2164-3 1.5V Efficiency
MIC2164-3 3.3V Efficiency
EFFICIENCY
EFFICIENCY
EFFICIENCY
VIN=5V
VIN=5V
VIN=5V
OUTPUT CURRENT
OUTPUT CURRENT
OUTPUT CURRENT
Feedback Voltage Load
0.85 0.84 0.85 0.84
Feedback Voltage Input Voltage
0.85 0.84
Feedback Voltage Voltage
FEEDBACK VOLTAGE
FEEDBACK VOLTAGE
FEEDBACK VOLTAGE
0.83 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75
0.83 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75
0.83 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75
VHSD=12V VIN=5V
VHSD=12V
VIN=5V
OUTPUT CURRENT
INPUT VOLTAGE
VOLTAGE
Feedback Voltage Temperature
0.810
MIC2164 Switching Frequency Load
MIC2164-2 Switching Frequency Load
SWITCHING FREQUENCY (kHz)
0.806 0.804 0.802 0.800 0.798 0.796 0.794 0.792 0.790
SWITCHING FREQUENCY (kHz)
0.808
FEEDBACK VOLTAGE
VIN=5V
VHSD=12V VIN=5V
VHSD=12V VIN=5V
TEMPERATURE (°C)
OUTPUT CURRENT
OUTPUT CURRENT
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Typical Characteristics (continued)
MIC2164-3 Switching Frequency Load
1150
MIC2164 Switching Frequency
MIC2164-2 Switching Frequency
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
1090 1060 1030 1000
SWITCHING FREQUENCY (kHz)
1120
VHSD=12V VIN=5V
VHSD=12V
VHSD=12V
OUTPUT CURRENT
INPUT VOLTAGE
INPUT VOLTAGE
MIC2164-3 Switching Frequency
1150
MIC2164 Switching Frequency VHSD
MIC2164-2 Switching Frequency VHSD
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
1120 1090 1060 1030 1000
SWITCHING FREQUENCY (kHz)
VIN=5V
VIN=5V VOUT=2.5V
VHSD=12V
INPUT VOLTAGE
VOLTAGE
VOLTAGE
MIC2164-3 Switching Frequency VHSD
1150
MIC2164 Switching Frequency Temperature
MIC2164-2 Switching Frequency Temperature
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
SWITCHING FREQUENCY (kHz)
1120 1090 1060 1030 1000
VIN=5V
VIN=5V
VIN=5V
VOLTAGE
TEMPERATURE (°C)
TEMPERATURE (°C)
MIC2164-3 Switching Frequency Temperature
1150
Current Limit Threshold Feedback Voltage Percentage
Current Limit Threshold Temperature
CURRENT LIMIT THRESHOLD (mV)
VFB=0.8V VFB=0V
SWITCHING FREQUENCY (kHz)
CURRENT LIMIT THRESHOLD (mV)
1120 1090 1060 1030 1000
VIN=5V
VIN=5V
TEMPERATURE (°C)
Feedback Voltage Percentage
TEMPERATURE (°C)
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Typical Characteristics (continued)
Quiescent Supply Current Input Voltage
QUIESCENT SUPPLY CURRENT (mA)
INPUT VOLTAGE
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Functional Characteristics
MIC2164-2 Load Transient
1.0H Cout 1100F
Vout (200mV/div) AC-coupled
Vhsd Vout 3.3V Iout (5A/div)
Time 200s/div
MIC2164-3 Load Transient
1.0H Cout 660F
Vout (200mV/div) AC-coupled
Vhsd Vout 3.3V Iout (5A/div)
Time 200s/div
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Functional Characteristics (continue)
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Functional Characteristics (continue)
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Functional Characteristics (continue)
MIC2164-2 Output Voltage Ripple
(5A/div) 1.0H Cout 1100F VOUT (50mV/div) AC-coupled
Vhsd Vout 3.3V Iout
Time 2s/div
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Functional Diagram
Figure MIC2164/-2/-3 Block Diagram
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3 estimated-ON-time method results constant switching frequency MIC2164/-2/-3. actual time varied with different rising falling time external MOSFETs. Therefore, type external MOSFETs, output load current, control circuitry power supply will modify actual time switching frequency. Also, minimum results lower switching frequency high VHSD VOUT applications, such 1.0V MIC2164-3 application. minimum measured MIC2164 evaluation board about 138ns. During load transient, switching frequency changed varying time. illustrate control loop, steady-state scenario load transient scenario analyzed. easy analysis, gain amplifier assumed With this assumption, inverting input error comparator same voltage. Figure shows MIC2164/-2/-3 control loop timing during steady-state. During steady-state, amplifier senses voltage ripple, which proportional output voltage ripple inductor current ripple, trigger ON-time period. time predetermined estimation. ending time controlled voltage. valley voltage ripple, which below than VREF, period ends next ON-time period triggered through control logic circuitry.
Functional Description
MIC2164/-2/-3 constant on-time synchronous buck controller family built cost high performance. They designed wide input voltage range from high output power buck converters. estimated-ON-time method applied MIC2164/-2/-3 obtain constant switching frequency simplify control compensation. overcurrent protection implemented without external sense resistor. includes internal soft-start function which reduces power supply input surge current start-up controlling output voltage rise time. Theory Operation MIC2164/-2/-3 constant on-time buck controller family. Figure illustrates block diagram control loop. output voltage variation will sensed MIC2164/-2/-3 feedback voltage divider compared 0.8V reference voltage VREF error comparator through gain transconductance (gm) amplifier, which improves MIC2164/-2/-3 converter output voltage regulation. voltage decreases output amplifier below 0.8V, error comparator will trigger control logic generate ON-time period, which logic high logic low. ON-time period length predetermined "FIXED ESTIMATION" circuitry:
TON(estimated) VOUT VHSD
where VOUT output voltage, VHSD power stage input voltage, switching frequency (300kHz MIC2164, 600kHz MIC2164-2, 1MHz MIC2164-3). After ON-time period, MIC2164/-2/-3 goes into OFF-time period, which logic logic high. OFF-time period length depending voltage most cases. When voltage decreases output amplifier below 0.8V, ON-time period trigger OFF-time period ends. OFF-time period decided voltage less than minimum time TOFF(min), which about 363ns typical, MIC2164/-2/-3 control logic will apply TOFF(min) instead. TOFF(min) required charging. maximum duty cycle obtained from 363ns TOFF(min):
Dmax TOFF(min) 363ns
Figure MIC2164/-2/-3 Control Loop Timing
where 1/fSW. recommended MIC2164/-2/-3 with time close TOFF(min) steady state.
Figure shows load transient scenario MIC2164/-2/-3 converter. output voltage drops sudden load increasing, which would cause voltage less than VREF. This will cause error comparator trigger ON-time period. ON-time period, minimum time TOFF(min) generated charge since voltage still below VREF. Then, next ON-time period triggered voltage. Therefore, switching frequency changes during load transient.
M9999-061209-A
June 2009
Micrel, Inc. With varying duty cycle switching frequency, output recovery time fast output voltage deviation small MIC2164/-2/-3 converter.
MIC2164/-2/-3 circuitry disabled reduce current consumption. should powered earlier than VHSD make soft-start function behavior correctly. Current Limit MIC2164/-2/-3 uses RDS(ON) low-side power MOSFET sense over-current conditions. lower-side MOSFET used because displays much lower parasitic oscillations during switching then high-side MOSFET. Using low-side MOSFET RDS(ON) current sense excellent method circuit protection. This method will avoid adding cost, board space power losses taken discrete current sense resistors. each switching cycle MIC2164/-2/-3 converter, inductor current sensed monitoring low-side MOSFET period. sensed voltage compared with current-limit threshold voltage after blanking time 150ns. sensed voltage over VCL, which 130mV typical 0.8V feedback voltage, MIC2164/-2/-3 turns high-side MOSFET soft-start sequence trigged. This mode operation called "hiccup mode" purpose protect down stream load case hard short. current limit threshold fold back characteristics related voltage. Please refer "Typical Characteristics" curve voltage. circuit Figure illustrates MIC2164/-2/-3 current limiting circuit.
Figure MIC2164/-2/-3 Load-Transient Response
Unlike current-mode control, MIC2164/-2/-3 uses output voltage ripple, which proportional inductor current ripple output capacitor large enough, trigger ON-time period. predetermined time makes MIC2164/-2/-3 control loop advantage constant on-time mode control. Therefore, slope compensation, which necessary current-mode control, required MIC2164/-2/-3 family. MIC2164/-2/-3 family stability concern: voltage ripple should phase with inductor current ripple large enough sensed amplifier error comparator. recommended minimum voltage ripple 20mV. output capacitor selected, voltage ripple small sensed amplifier error comparator. Also, output voltage ripple voltage ripple phase with inductor current ripple output capacitor very low. Therefore, ripple injection required output capacitor. Please refer "Ripple Injection" subsection "Application Information" more details about ripple injection. Soft-Start Soft-start reduces power supply input surge current startup controlling output voltage rise time. input surge appears while output capacitor charged slower output rise time will draw lower input surge current. MIC2164/-2/-3 implements internal digital soft-start making 0.8V reference voltage VREF ramp from 100% about with 9.7mV step. Therefore, output voltage controlled increase slowly staircase VREF ramp. Once soft-start ends, related June 2009
Figure MIC2164/-2/-3 Current Limiting Circuit
Using typical value 130mV, current limit value roughly estimated
130mV DS(ON)
designs where current ripple significant compared load current IOUT, duty cycle operation, calculating current limit should take into account that sensing peak inductor current that there blanking delay approximately 150ns.
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
TDLY IL(pp) 130mV DS(ON) IL(pp) VOUT
where VOUT output voltage TDLY Current limit blanking time, 150ns typical IL(pp) Inductor current ripple peak-to-peak value Duty Cycle Switching frequency MOSFET RDS(ON) varies with temperature; therefore, recommended margin above equation avoid false current limiting increased MOSFET junction temperature rise. also recommended connect directly drain low-side MOSFET accurately sense MOSFETs RDS(ON).
MOSFET Gate Drive MIC2164/-2/-3 high-side drive circuit designed switch N-Channel MOSFET. Block Diagram Figure shows bootstrap circuit, consisting Schottky diode recommended) CBST. This circuit supplies energy high-side drive circuit. Capacitor CBST charged while low-side MOSFET voltage approximately When high-side MOSFET driver turned energy from CBST used turn MOSFET high-side MOSFET turns voltage increases approximately VHSD. Diode reversed biased CBST floats high while continuing keep highside MOSFET bias current high-side driver less than 10mA 0.1F sufficient hold gate voltage with minimal droop power stroke (high-side switching) cycle, i.e. 10mA 3.33s/0.1F 333mV MIC2164. When low-side MOSFET turned back CBST recharged through small resistor which series with CBST, slow down turn-on time high-side N-channel MOSFET. drive voltage derived from supply voltage VIN. nominal low-side gate drive voltage nominal high-side gate drive voltage approximately VDIODE, where VDIODE voltage drop across approximate 30ns delay between high-side low-side driver transitions used prevent current from simultaneously flowing unimpeded through both MOSFETs.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3 low-side MOSFET:
IG[low -side] (avg)
Application Information
MOSFET Selection MIC2164/-2/-3 controller works from power stage input voltages external 5.5V provide power turn external N-Channel power MOSFETs high- low-side switches. applications where necessary that power MOSFETs used sub-logic level full conduction mode 2.5V. applications when logic-level MOSFETs, whose operation specified 4.5V must used. There different criteria choosing high-side low-side MOSFETs. These differences more significant lower duty cycles such 1.8V conversion. such application, high-side MOSFET required switch quickly possible minimize transition losses, whereas low-side MOSFET switch slower, must handle larger currents. When duty cycle approaches 50%, current carrying capability high-side MOSFET starts become critical. important note that on-resistance MOSFET increases with increasing temperature. 75°C rise junction temperature will increase channel resistance MOSFET resistance specified 25°C. This change resistance must accounted when calculating MOSFET power dissipation calculating value current limit. Total gate charge charge required turn MOSFET under specified operating conditions (VDS VGS). gate charge supplied MIC2164/-2/-3 gate-drive circuit. 300kHz switching frequency above, gate charge significant source power dissipation MIC2164/2/-3. output load, this power dissipation noticeable reduction efficiency. average current required drive high-side MOSFET
IG[high-side] (avg)
Since current from gate drive comes from VIN, power dissipated MIC2164/-2/-3 gate drive
PGATEDRIVE .(IG[high-side] (avg) IG[low -side] (avg))
convenient figure merit switching MOSFETs resistance times total gate charge RDS(ON) Lower numbers translate into higher efficiency. gate-charge logic-level MOSFETs good choice with MIC2164/-2/-3. Also, RDS(ON) lowside MOSFET will determine current limit value. Please refer "Current Limit" subsection "Functional Description" more details. Parameters that important MOSFET switch selection are: Voltage rating On-resistance
Total gate charge voltage ratings high-side low-side MOSFETs essentially equal power stage input voltage VHSD. safety factor should added VDS(max) MOSFETs account voltage spikes circuit parasitic elements. power dissipated MOSFETs conduction losses during on-time (PCONDUCTION) switching losses during period time when MOSFETs turn (PAC).
PCONDUCTION
PCONDUCTION ISW(RMS) DS(ON)
PAC(off PAC(on)
where: IG[high-side](avg) Average high-side MOSFET gate current Total gate charge high-side MOSFET taken from manufacturer's data sheet VIN. Switching Frequency low-side MOSFET turned because internal body diode external freewheeling diode conducting during this time. switching loss low-side MOSFET usually negligible. Also, gate-drive current low-side MOSFET more accurately calculated using CISS instead gate charge.
where: RDS(ON) on-resistance MOSFET switch Duty Cycle VOUT VHSD Making assumption that turn-on turn-off transition times equal; transition times approximated
VHSD
(10)
where: CISS COSS measured gate-drive current total high-side MOSFET switching loss
(VHSD
(11)
June 2009
M9999-061209-A
Micrel, Inc. where: Switching transition time Body diode drop (0.5v) Switching Frequency high-side MOSFET switching losses increase with switching frequency input voltage VHSD. low-side MOSFET switching losses negligible ignored these calculations.
Inductor Selection Values inductance, peak, currents required select output inductor. input output voltages inductance value determine peak-to-peak inductor ripple current. Generally, higher inductance values used with higher input voltages. Larger peak-to-peak ripple currents will increase power dissipation inductor MOSFETs. Larger output ripple currents will also require more output capacitance smooth larger ripple current. Smaller peak-to-peak ripple currents require larger inductance value therefore larger more expensive inductor. good compromise between size, loss cost inductor ripple current equal maximum output current. inductance value calculated equation below.
VOUT VHSD(max) VOUT
MIC2164/-2/-3 Lower cost iron powder cores used increase core loss will reduce efficiency power supply. This especially noticeable output power. winding resistance decreases efficiency higher output current levels. winding resistance must minimized although this usually comes expense larger inductor. power dissipated inductor equal core copper losses. higher output loads, core losses usually insignificant ignored. lower output currents, core losses significant contributor. Core loss information usually available from magnetics vendor. Copper loss inductor calculated equation below: PINDUCTORCu=IL(RMS)2 RWINDING (16) resistance copper wire, RWINDING, increases with temperature. value winding resistance used should operating temperature. RWINDING RWINDING(20°c) 0.0042 T20°C)) (17) where: temperature wire under full load T20°C ambient temperature RWINDING(20°C) room temperature winding resistance (usually specified manufacturer)
Output Capacitor Selection type output capacitor usually determined (equivalent series resistance). Voltage current capability other important factors selecting output capacitor. Recommended capacitors tantalum, low-ESR aluminum electrolytic, OS-CON POSCAPS. output capacitor's usually main cause output ripple. output capacitor also affects control loop from stability point view. maximum value calculated:
COUT VOUT(pp) IL(PP)
VHSD(max) IOUT(max)
(12)
where: switching frequency ratio ripple current output current VHSD(max) maximum power stage input voltage peak-to-peak inductor current ripple
IL(PP VOUT VHSD(max) VOUT VHSD(max)
(13)
(18)
peak inductor current equal average output current plus half peak-to-peak inductor current ripple.
IL(PK) IOUT(max) IL(PP)
(14)
inductor current used calculate losses inductor.
IL(RMS) IOUT(max)2 IL(PP)
where: VOUT(pp) peak-to-peak output voltage ripple IL(PP) peak-to-peak inductor current ripple total output ripple combination output capacitance. total ripple calculated below:
IL(PP) IL(PP) VOUT(pp) (19)
(15)
Maximizing efficiency requires proper selection core material minimizing winding resistance. high frequency operation MIC2164/-2/-3 requires ferrite materials most cost sensitive applications. June 2009
M9999-061209-A
Micrel, Inc. Where: duty cycle COUT output capacitance value switching frequency described "Theory Operation" subsection "Functional Description", MIC2164/-2/-3 requires least 20mV peak-to-peak ripple make amplifier error comparator behavior properly. Also, output voltage ripple should phase with inductor current. Therefore, output voltage ripple caused output capacitor COUT should much smaller than ripple caused output capacitor ESR. capacitors selected output capacitors, such ceramic capacitors, ripple injection method applied provide enough voltage ripples. Please refer "Ripple Injection" subsection more details. voltage rating capacitor should twice output voltage tantalum greater aluminum electrolytic OS-CON. output capacitor current calculated below: IL(PP) ICOUT (RMS) (20) power dissipated output capacitor
PDISS(COUT ICOUT (RMS) COUT
MIC2164/-2/-3 output voltage, shown Figure
Figure Voltage-Divider Configuration
output voltage determined equation:
(25) where VREF 0.8V. typical value between 10k. large, allow noise introduced into voltage feedback loop. small value, will decrease efficiency power supply, especially light loads. Once selected, calculated using: VOUT VREF VREF VOUT VREF
(26)
(21)
Input Capacitor Selection input capacitor power stage input VHSD should selected ripple current rating voltage rating. Tantalum input capacitors fail when subjected high inrush currents, caused turning input supply tantalum input capacitor's voltage rating should least times maximum input voltage maximize reliability. Aluminum electrolytic, OS-CON, multilayer polymer film capacitors handle higher inrush currents without voltage derating. input voltage ripple will primarily depend upon input capacitor's ESR. peak input current equal peak inductor current,
IL(PK
External Schottky Diode (Optional) external freewheeling diode, which necessary, used keep inductor current flow continuous while both MOSFETs turned off. This dead time prevents current from flowing unimpeded through both MOSFETs typically 30ns. diode conducts twice during each switching cycle. Although average current through this diode small, diode must able handle peak current.
ID(avg) IOUT 30ns
(27)
reverse voltage requirement diode
VDIODE(rrm) VHSD power dissipated Schottky diode
PDIODE ID(avg)
(22)
(28)
input capacitor must rated input current ripple. value input capacitor current determined maximum output current. Assuming peak-to-peak inductor current ripple low:
ICIN(RMS IOUT(max)
(23) (24)
power dissipated input capacitor PDISS(CIN)
Voltage Setting Components MIC2164/-2/-3 requires resistors
where, forward voltage peak diode current. external Schottky diode necessary circuit operation since low-side MOSFET contains parasitic body diode. external diode will improve efficiency decrease high frequency noise. MOSFET body diode used, must rated handle peak average current. body diode relatively slow reverse recovery time relatively high forward voltage drop. power lost diode proportional forward voltage drop diode. high-side MOSFET starts turn body diode
June 2009
M9999-061209-A
Micrel, Inc. becomes short circuit reverse recovery period, dissipating additional power. diode recovery circuit inductance will cause ringing during high-side MOSFET turn-on. external Schottky diode conducts lower forward voltage preventing body diode MOSFET from turning lower forward voltage drop dissipates less power than body diode. lack reverse recovery mechanism Schottky diode causes less ringing less power loss. Depending upon circuit components operating conditions, external Schottky diode will give 1/2% improvement efficiency.
Ripple Injection minimum voltage ripple requested MIC2164/-2/-3 amplifier error comparator 20mV. However, output voltage ripple generally designed output voltage. output voltage, such output, output voltage ripple only 10mV 20mV, voltage ripple less than 20mV. voltage ripple small that amplifier error comparator could sense MIC2164/-2/-3 will lose control output voltage regulated. order have some amount voltage ripple, ripple injection method applied output voltage ripple applications. applications divided into three situations according amount voltage ripple: Enough ripple voltage large output capacitors. shown Figure converter stable without adding this situation. voltage ripple
COUT (pp) (29) where IL(pp) peak-to-peak value inductor current ripple. Inadequate ripple voltage small output capacitors. output voltage ripple into through feedforward capacitor this situation, shown Figure typical value between 100nF. With feedforward capacitor, voltage ripple very close output voltage ripple: VFB(pp) VFB(pp) (pp)
MIC2164/-2/-3
Figure Enough Ripple
Figure Inadequate Ripple
Figure Invisible Ripple
this situation, output voltage ripple less than 20mV. Therefore, additional ripple injected into from switching node resistor Rinj capacitor Cinj, shown Figure injected ripple (31) VFB(pp) VHSD
R1//R2 Rinj R1//R2
(32)
where VHSD Power stage input voltage Duty Cycle switching frequency
(R1// Rinj)
(30)
Invisible ripple voltage very output capacitors.
formula (31) (32), assumed that time constant associated with must much greater than switching period:
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Step Select Rinj according expected feedback voltage ripple. According equation (32),
VFB(pp
VHSD
voltage divider resistors range, 100nF easily satisfy large time constant consumption. Also, 100nF injection capacitor Cinj used order considered short wide range frequencies. process sizing ripple injection resistor capacitors Step Select feed output ripples into feedback make sure large time constant assumption satisfied. Typical choice 100nF range.
(33)
Then value Rinj obtained
(34)
Step Select Cinj 100nF, which could considered short wide range frequencies.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3 capacitor very critical. Connections must made with wide trace.
Inductor
Layout Guideline
Warning!!! minimize output noise, follow these layout recommendations. Layout critical achieve reliable, stable efficient performance. ground plane required control minimize inductance power, signal return paths. following guidelines should followed insure proper operation MIC2164/-2/-3 converter.
Keep inductor connection switch node (LX) short. route digital lines underneath close inductor. Keep switch node (LX) away from feedback (FB) pin. should connected directly drain low-side MOSFET accurate sense voltage across low-side MOSFET. minimize noise, place ground plane underneath inductor. wide trace connect output capacitor ground terminal input capacitor ground terminal. Phase margin will change output capacitor value changes. Contact factory output capacitor different from what shown BOM. feedback trace should separate from power trace connected close possible output capacitor. Sensing long high current load trace degrade load regulation. Place Schottky diode same side board MOSFETs input capacitor. connection from Schottky diode's Anode input capacitors ground terminal must short possible. diode's Cathode connection switch node (LX) must keep short possible. Place snubber same side board close MOSFETs possible.
Place MOSFETs close point load (POL). traces route input output power lines. Signal power grounds should kept separate connected only location. Place input capacitor next. Place input capacitors same side board close MOSFETs possible. Keep both PGND connections short. Place several vias ground plane close input capacitor ground terminal. either dielectric input capacitors. type capacitors. replace ceramic input capacitor with other type capacitor. type capacitor placed parallel with input capacitor. Tantalum input capacitor placed parallel with input capacitor, must recommended switching regulator applications operating voltage must derated 50%. "Hot-Plug" applications, Tantalum Electrolytic bypass capacitor must used limit overvoltage spike seen input supply with power suddenly applied. additional Tantalum Electrolytic bypass input capacitor 22uF higher required input power connection. 0.1µF capacitors, which connect terminal, must located right terminal very noise sensitive placement
Output Capacitor
Input Capacitor
Schottky Diode (Optional)
Snubber
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Evaluation Board Schematics
Figure Schematic MIC2164 Evaluation Board
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Bill Materials
Item C17, Part Number 06035C104KAT 0805ZD225MAT GRM216R61A225ME24D C2012X5R1A225K/0.85 222215095001 1210YD226MAT GRM32ER61C226ME20L 0805ZD105KAT GRM219R61A105MA01D 06035C223KAT GRM188R71H223MA01D 16ME1000WGL 12106D107MAT GRM32ER60J107ME20L C3225X5R0J107M 06035C102KAT SD103BWS CDEP147NP-1R5M FDS6699S FDS7766S CMPDM7002A 2N7002E-T1-E3 CRCW06032R21FKEY3 CRCW06030000FKEY3 CRCW06034992FKEY3 CRCW06031R21FKEY3 CRCW06031002FKEY3 CRCW06034751FKEY3 CRCW06038061FKEY3 CRCW06034022FKEY3 CRCW06033241FKEY3 MIC2164YMM MIC5233-5.0YM5 Manufacturer
Description 0.1µF Ceramic Capacitor, X7R, Size 0603, 2.2µF Ceramic Capacitor, X5R, Size 0805, 220µF Aluminum Capacitor, SMD, 22µF Ceramic Capacitor, X5R, Size 1210, Ceramic Capacitor, X5R, Size 0805, 22nF Ceramic Capacitor, X7R, Size 0603, 22nF Ceramic Capacitor, X7R, 0603, 1000µF Aluminum Capacitor, 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V Ceramic Capacitor, X7R, 0603, Small Signal Schottky Diode 1.5µH Inductor, 27.2A Saturation Current N-Channel MOSFET 4.5m Rds(on) 4.5V N-Channel MOSFET 6.5m Rds(on) 4.5V
MuRata(2)
Vishay(4) MuRata MuRata MuRata Sanyo(5) muRata Vishay Sumida
Fairchild
Fairchild Central Semiconductor Vishay Vishay-Dale(4) Vishay-Dale Vishay-Dale Vishay-Dale Vishay-Dale Vishay-Dale Vishay-Dale Vishay-Dale Vishay-Dale Micrel. Inc.
Signal MOSFET, 2.21 Resistor, Size 0603, Resistor, Size 0603, 49.9k Resistor, Size 0603, 1.21 Resistor, Size 0603, Resistor, Size 0603, 4.75k Resistor, Size 0603, 8.06k Resistor, Size 0603, 40.2k Resistor, Size 0603, 3.24k Resistor, Size 0603, 300kHz Buck Controller
Micrel. Inc.
June 2009
M9999-061209-A
Micrel, Inc.
Notes:
MIC2164/-2/-3
AVX: www.avx.com MuRata: www.murata.com TDK: www.tdk.com Vishay: www.vishay.com Sanyo: www.sanyo.com Sumida: www.sumida.com Fairchild: www.fairchildsemi.com Central Semiconductor: www.centralsemi.com
Micrel, Inc: www.micrel.com
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Layout
Figure MIC2164 Evaluation Board Layer
Figure MIC2164 Evaluation Board Bottom Layer
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Figure MIC2164 Evaluation Board Mid-Layer
Figure MIC2164 Evaluation Board Mid-Layer
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Application Schematics Bill Materials
Figure MIC2164 3.3V Buck Converter
Bill Materials (MIC2164 3.3V 20A)
Item C17, Part Number 06035C104KAT 0805ZD225MAT 222215095001 1210YD226MAT 0805ZD105KAT 06035C223KAT 16ME1000WGL 12106D107MAT 06035C102KAT SD103BWS CDEP147NP-1R5M FDS6699S Manufacturer
Description 0.1µF Ceramic Capacitor, X7R, Size 0603, 2.2µF Ceramic Capacitor, X5R, Size 0805, 220µF Aluminum Capacitor, SMD, 22µF Ceramic Capacitor, X5R, Size 1210, Ceramic Capacitor, X5R, Size 0805, 22nF Ceramic Capacitor, X7R, Size 0603, 1000µF Aluminum Capacitor, 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V Ceramic Capacitor, X7R, Size 0603, Small Signal Schottky Diode 1.5µH Inductor, 27.2A Saturation Current N-Channel MOSFET 4.5m Rds(on) 4.5V
Vishay Sanyo Vishay Sumida
Fairchild
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Bill Materials (MIC2164 3.3V 20A)
Item
Notes:
Part Number FDS7766S CRCW06032R21FKEY3 CRCW06031R21FKEY3 CRCW06031002FKEY3 CRCW06033241FKEY3 MIC2164YMM MIC5233-5.0YM5
Manufacturer Fairchild Vishay Dale Vishay Dale Vishay Dale Vishay Dale Micrel. Inc.
Description N-Channel MOSFET 6.5m Rds(on) 4.5V 2.21 Resistor, Size 0603, 1.21 Resistor, Size 0603, Resistor, Size 0603, 3.24k Resistor, Size 0603 300kHz Buck Controller
Micrel. Inc.
AVX: www.avx.com Vishay: www.vishay.com Sanyo: www.sanyo.com Sumida: www.sumida.com Fairchild: www.fairchildsemi.com
Micrel, Inc: www.micrel.com.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Figure MIC2164 1.8V Buck Converter
Bill Materials (MIC2164 1.8V 10A)
Item C17, Part Number 06035C104KAT 0805ZD225MAT 222215095001 1210YD106MAT 0805ZD105KAT 06035C223KAT 6SEPC560MX 12106D107MAT 06035C102KAT SD103BWS CDEP105-2R0MC-32 FDS7764A Manufacturer
Description 0.1µF Ceramic Capacitor, X7R, Size 0603, 2.2µF Ceramic Capacitor, X5R, Size 0805, 220µF Aluminum Capacitor, SMD, 10µF Ceramic Capacitor, X5R, Size 1210, Ceramic Capacitor, X5R, Size 0805, 22nF Ceramic Capacitor, X7R, Size 0603, 560µF OSCON Capacitor, 6.3V 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V Ceramic Capacitor, X7R, Size 0603, Small Signal Schottky Diode 2.0µH Inductor, 15.8A Saturation Current N-Channel MOSFET 7.5m Rds(on) 4.5V
Vishay Sanyo Vishay Sumida
Fairchild
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Bill Materials (MIC2164 1.8V 10A)
Item
Notes:
Part Number CRCW06032R21FKEY3 CRCW06031R21FKEY3 CRCW06031002FKEY3 CRCW06038061FKEY3 MIC2164YMM MIC5233-5.0YM5
Manufacturer Vishay Dale Vishay Dale Vishay Dale Vishay Dale Micrel. Inc.(6) Micrel. Inc.
Description 2.21 Resistor, Size 0603, 1.21 Resistor, Size 0603, Resistor, Size 0603, 8.06k Resistor, Size 0603, 300kHz Buck Controller
AVX: www.avx.com Vishay: www.vishay.com Sanyo: www.sanyo.com Sumida: www.sumida.com Fairchild: www.fairchildsemi.com
Micrel, Inc: www.micrel.com.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Figure MIC2164 1.0V Buck Converter
Bill Materials (MIC2164 1.0V
Item C17, C11, C12, Part Number 06035C104KAT 0805ZD225MAT 222215095001 1210YD106MAT 0805ZD105KAT 06035C223KAT 12106D107MAT 06035C102KAT SD103BWS CDRH104RNP-3R8 FDS6910 CRCW06032R21FKEY3 CRCW06031R21FKEY3 Manufacturer
Description 0.1µF Ceramic Capacitor, X7R, Size 0603, 2.2µF Ceramic Capacitor, X5R, Size 0805, 220µF Aluminum Capacitor, SMD, 10µF Ceramic Capacitor, X5R, Size 1210, Ceramic Capacitor, X5R, Size 0805, 22nF Ceramic Capacitor, X7R, Size 0603, 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V Ceramic Capacitor, X7R, Size 0603, Small Signal Schottky Diode 3.8µH Inductor, Saturation Current Dual N-Channel MOSFET Rds(on) 4.5V 2.21 Resistor, Size 0603, 1.21 Resistor, Size 0603,
Vishay(2) Vishay Sumida
Fairchild(5) Vishay Dale(2) Vishay Dale
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Bill Materials (MIC2164 1.0V
Item
Notes:
Part Number CRCW06031002FKEY3 CRCW06034022FKEY3 MIC2164YMM MIC5233-5.0YM5
Manufacturer Vishay Dale Vishay Dale Micrel. Inc.
Description Resistor, Size 0603, 40.2k Resistor, Size 0603, 300kHz Buck Controller
Micrel. Inc.
AVX: www.avx.com Vishay: www.vishay.com Sanyo: www.sanyo.com Sumida: www.sumida.com Fairchild: www.fairchildsemi.com
Micrel, Inc: www.micrel.com.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Figure MIC2164-2 3.3V Buck Converter
Bill Materials (MIC2164-2 3.3V 15A)
Item C17, Part Number 06035C104KAT 0805ZD225MAT 222215095001 1210YD226MAT 0805ZD105KAT 06035C472KAT 16ME1000WGL 12106D107MAT 06035C102KAT SD103BWS HCP1305-1R0 FDS8672S Manufacturer
Description 0.1µF Ceramic Capacitor, X7R, Size 0603, 2.2µF Ceramic Capacitor, X5R, Size 0805, 220µF Aluminum Capacitor, SMD, 22µF Ceramic Capacitor, X5R, Size 1210, Ceramic Capacitor, X5R, Size 0805, 4.7nF Ceramic Capacitor, X7R, Size 0603, 1000µF Aluminum Capacitor, 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V Ceramic Capacitor, X7R, Size 0603, Small Signal Schottky Diode 1.0µH Inductor, Current N-Channel MOSFET 7.0m Rds(on) 4.5V
Vishay Sanyo Vishay Cooper Bussmann(4) Fairchild(5)
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Bill Materials (MIC2164-2 3.3V 15A)
Item
Notes:
Part Number FDS8874 CRCW06032R21FKEY3 CRCW06031R21FKEY3 CRCW06031002FKEY3 CRCW06034021FKEY3 CRCW06033241FKEY3 MIC2164-2YMM MIC5233-5.0YM5
Manufacturer Fairchild Vishay Dale Vishay Dale Vishay Dale Vishay Dale Vishay Dale Micrel. Inc.
Description N-Channel MOSFET 7.0m Rds(on) 4.5V 2.21 Resistor, Size 0603, 1.21 Resistor, Size 0603, Resistor, Size 0603, 4.02k Resistor, Size 0603, 3.24k Resistor, Size 0603 600kHz Buck Controller
Micrel. Inc.
AVX: www.avx.com Vishay: www.vishay.com Sanyo: www.sanyo.com Cooper Bussmann: www.cooperbussmann.com Fairchild: www.fairchildsemi.com
Micrel, Inc: www.micrel.com.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Figure MIC2164-3 1.8V Buck Converter
Bill Materials (MIC2164-3 1.8V 10A)
Item C17, Part Number 06035C104KAT 0805ZD225MAT 222215095001 1210YD106MAT 0805ZD105KAT 06035C222KAT 6SEPC560MX 12106D107MAT 06035C102KAT SD103BWS HCF1305-1R0 FDS8672S CRCW06032R21FKEY3 Manufacturer AVX(1) Vishay Sanyo Vishay Cooper Bussmann(4) Fairchild(5) Vishay Dale
Description 0.1µF Ceramic Capacitor, X7R, Size 0603, 2.2µF Ceramic Capacitor, X5R, Size 0805, 220µF Aluminum Capacitor, SMD, 10µF Ceramic Capacitor, X5R, Size 1210, Ceramic Capacitor, X5R, Size 0805, 2.2nF Ceramic Capacitor, X7R, Size 0603, 560µF OSCON Capacitor, 6.3V 100µF Ceramic Capacitor, X5R, Size 1210, 6.3V Ceramic Capacitor, X7R, Size 0603, Small Signal Schottky Diode 1.0µH Inductor, Saturation Current N-Channel MOSFET 7.0m Rds(on) 4.5V 2.21 Resistor, Size 0603,
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Bill Materials (MIC2164-3 1.8V 10A)
Item
Notes:
Part Number CRCW06031R21FKEY3 CRCW06031002FKEY3 CRCW06032001FKEY3 CRCW06038061FKEY3 MIC2164-3YMM MIC5233-5.0YM5
Manufacturer Vishay Dale Vishay Dale Vishay Dale Vishay Dale Micrel. Inc.(6) Micrel. Inc.
Description 1.21 Resistor, Size 0603, Resistor, Size 0603, Resistor, Size 0603, 8.06k Resistor, Size 0603, 1MHz Buck Controller
AVX: www.avx.com Vishay: www.vishay.com Sanyo: www.sanyo.com Cooper: www.cooperbussmann.com Fairchild: www.fairchildsemi.com
Micrel, Inc: www.micrel.com.
June 2009
M9999-061209-A
Micrel, Inc.
MIC2164/-2/-3
Package Information
10-Pin MSOP (MM)
MICREL, INC. 2180 FORTUNE DRIVE JOSE, 95131
(408) 944-0800 (408) 474-1000 http://www.micrel.com
information furnished Micrel this data sheet believed accurate reliable. However, responsibility assumed Micrel use. Micrel reserves right change circuitry specifications time without notification customer. Micrel Products designed authorized components life support appliances, devices systems where malfunction product reasonably expected result personal injury. Life support devices systems devices systems that intended surgical implant into body support sustain life, whose failure perform reasonably expected result significant injury user. Purchaser's sale Micrel Products life support appliances, devices systems Purchaser's risk Purchaser agrees fully indemnify Micrel damages resulting from such sale. 2009 Micrel, Incorporated.
June 2009
M9999-061209-A

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