DESCRIPTIO September 2003 Integrated Switches: 2.4A Buck, 2.
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LT1943 High Current Quad Output Regulator Panel
DESCRIPTIO
September 2003
Integrated Switches: 2.4A Buck, 2.6A Boost, 0.35A Boost, 0.35A Inverter (Guaranteed Minimum Current Limit) Fixed Frequency, Noise Outputs Soft Start Outputs Externally Programmable Delay Integrated Schottky Diode Output PGOOD AVDD Output Disconnect 4.5V Input Voltage Range PanelProtectCircuitry Disables Upon Fault Thermally Enhanced 28-Lead TSSOP
APPLICATIO
Large TFT-LCD Desktop Monitor Displays Flat Panel Television
LT®1943 quad output adjustable switching regulator provides power large panels. device, housed profile thermally enhanced TSSOP package, generate 3.3V logic supply along with triple output supply required panel. Operating from input range 4.5V 22V, step-down regulator provides voltage output VLOGIC with current. high-power step-up converter, lowerpower step-up converter inverting converter provide three independent output voltages AVDD, VOFF required panel. high-side provides delayed turn-on signal handle 30mA. Protection circuitry ensures disabled four outputs more than below normal voltage. switchers synchronized internal 1.2MHz clock, allowing profile inductors ceramic capacitors throughout. current mode architecture provides excellent transient response. best flexibility, outputs adjustable. Soft-start included four channels. PGOOD drive optional PMOS pass device provide output disconnect AVDD output.
registered trademarks Linear Technology Corporation. PannelProtect trademark Linear Technology Corporation.
TYPICAL APPLICATIO
VOFF -10V 50mA 2.2µF ZHCS400 VIN, 0.47µF 80.6k ZHCS400 NFB4 10.0k 10pF 10µH BIAS BOOST CMDSH-3 16.2k 0.22µF 10µF
10µH
B240A
AVDD 500mA 95.3k 10µF
33µH
10µH
RUN-SS SS-234 PGOOD 232k PGOOD 0.015µF 0.015µF 0.047µF
10.0k
LT1943
30mA
RUN-SS 2V/DIV VLOGIC 5V/DIV AVDD 10V/DIV VOFF 10V/DIV 20V/DIV 50V/DIV IIN(AVG) 1A/DIV 5ms/DIV
VLOGIC 3.3V
4.7µH B230A
10.0k 22µF 27.4k 100pF 2.2nF 6.81k
SGND
10.0k 2.2µF
100pF 2.2nF
47.5k 100pF 680pF
100pF 2.2nF
0.47µF
Figure Quad Output TFT-LCD Power Supply
1943
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.
Startup Waveform
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LT1943
ABSOLUTE
(Note
RATI
PACKAGE/ORDER ATIO
VIEW NFB4 PGOOD BIAS RUN-SS SS-234
Voltage BOOST Voltage BOOST Voltage Above BIAS Voltage SW2, Voltages Voltage FB1, FB2, FB3, Voltages NFB4 Voltage +6V, -0.6V VC1, VC2, VC3, Voltages RUN-SS, SS-234 Voltages PGOOD Voltage Voltage Voltage Voltage Junction Temperature 125°C Operating Temperature Range (Note .-40°C 85°C Storage Temperature Range .-65°C 150°C Lead Temperature (Soldering, sec). 300°C
ORDER PART NUMBER LT1943EFE
SGND BOOST
PART MARKING 1943EFE
PACKAGE 28-LEAD PLASTIC TSSOP EXPOSED (PIN GROUND (MUST SOLDERED PCB)
TJMAX 150°C, 25°C/W, 7.5°C/W
Consult Marketing parts specified with wider operating temperature ranges.
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 12V, RUN-SS, SS-234 2.5V unless otherwise noted.
PARAMETER Minimum Input Voltage Maximum Input Voltage Quiescent Current RUN-SS, SS-234 Current RUN-SS, SS-234 Threshold BIAS Voltage Begin SS-234 Charge BIAS Current Threshold Offset Begin Charge Current Source Threshold Power Switch Drop Maximum Current PGOOD Threshold Offset PGOOD Leakage Master Oscillator Frequency
ELECTRICAL CHARACTERISTICS
CONDITIONS
UNITS
Switching RUN-SS SS-234 RUN-SS, SS-234 0.4V
10.5
3.15 1.35 1.46
BIAS 3.1V, Switches (Note Pins 1.5V Pins 1.5V Current 30mA VPGOOD
Foldback Switching Frequency Frequency Shift Threshold
Pins 200kHz
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LT1943
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. 12V, RUN-SS, SS-234 2.5V unless otherwise noted.
PARAMETER SWITCH (2.4A BUCK) Voltage
ELECTRICAL CHARACTERISTICS
CONDITIONS
1.23 1.22
1.25 0.01
1.27 1.27 0.03
UNITS µmho
Voltage Line Regulation Bias Current Error Amplifier Voltage Gain Error Amplifier Transconductance Switch Current Limit Switch VCESAT Switch Leakage Current Minimum BOOST Voltage Above BOOST Current Maximum Duty Cycle (SW1) SWITCH (2.6A BOOST) Voltage
4.5V (Note Duty Cycle 1.5V 1.5A 1.5A
1.23 1.22 1.25 0.01
1.27 1.27 0.03 1000
µmho
Voltage Line Regulation Bias Current Error Amplifier Voltage Gain Error Amplifier Transconductance Switch Current Limit Switch VCESAT Switch Leakage Current BIAS Current Maximum Duty Cycle (SW2) SWITCH (350mA BOOST) Voltage
4.5V (Note
ISW2 1.5V ISW2
1.23 1.22
1.25 0.01 1.27 1.27 0.03
µmho
Voltage Line Regulation Bias Current Error Amplifier Voltage Gain Error Amplifier Transconductance Switch Current Limit Switch VCESAT Switch Leakage Current BIAS Current Maximum Duty Cycle (SW3)
4.5V (Note
0.35
ISW3 0.2A 1.5V ISW3 0.2A
Schottky Diode Drop
170mA
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LT1943
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. RUN-SS, SS-234 2.5V unless otherwise noted.
PARAMETER SWITCH (350mA INVERTER) Voltage
ELECTRICAL CHARACTERISTICS
CONDITIONS
1.23 1.22
1.25 0.01
1.27 1.27 0.03 1.275 1.275 0.03
UNITS µmho
Voltage Line Regulation Bias Current NFB4 Voltage (VFB4-VNFB4)
4.5V (Note
1.215 1.205 1.245 0.01
NFB4 Voltage Line Regulation NFB4 Bias Current Error Amplifier Voltage Gain Error Amplifier Transconductance Switch Current Limit Switch VCESAT Switch Leakage Current BIAS Current Maximum Duty Cycle (SW4)
4.5V (Note
0.35
ISW4 0.3A ISW4 0.3A
Note Absolute Maximum Ratings those values beyond which life device impaired. Note LT1943E guaranteed meet performance specifications from 70°C. Specifications over -40°C 85°C operating temperature range assured design, characterization, correlation with statistical process controls.
Note held until FB1, FB2, ramp above threshold offset. Note Current flows into FB1, FB2, pins. Note Current flows NFB4 pin.
TYPICAL PERFOR CHARACTERISTICS
Maximum Output Current VLOGIC
25°C 4.7µH 3.3µH INPUT VOLTAGE
1943
VLOGIC MAXIMUM OUTPUT CURRENT
CURRENT
CURRENT
1943
Current Limit Duty Cycle
25°C
Current Limit
TYPICAL
MINIMUM
DUTY CYCLE
TEMPERATURE (°C)
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LT1943 TYPICAL PERFOR CHARACTERISTICS
MINIMUM Input Voltage Start, VOUT 3.3V
25°C 25°C
BOOST CURRENT (mA)
INPUT VOLTAGE
CURRENT
CURRENT
1943
LOAD CURRENT (mA)
Current Limit
VOLTAGE DROP (mV)
CURRENT
CURRENT
TEMPERATURE (°C)
VCESAT
25°C
VOLTAGE DROP (mV)
VOLTAGE DROP (mV)
VOLTAGE DROP (mV)
CURRENT
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BOOST Current
Current Limit
TEMPERATURE (°C)
1943
Current Limit
VCESAT
25°C
TEMPERATURE (°C)
CURRENT
1943
1943
1943
VCESAT
25°C
VCESAT
25°C
1943
CURRENT
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CURRENT
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LT1943 TYPICAL PERFOR CHARACTERISTICS
Current Limit
25°C
CURRENT (mA)
FREQUENCY (MHz)
SWITCHING FREQUENCY (MHz)
Reference Voltage
1.27
REFERENCE VOLTAGE
1.25
BIAS CURRENT (mA)
1.26
1.24
1.23
1.22
1943
Oscillator Frequency
TEMPERATURE (°C)
1943
Frequency Foldback
25°C
FEEDBACK VOLTAGE
1943
Bias Current
ISW2 1.5A ISW3 0.2A ISW4 0.3A
ISW2 ISW3 ISW4 TEMPERATURE (°C)
TEMPERATURE (°C)
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LT1943
CTIO
(Pins Exposed 29): Ground. both pins exposed directly local ground plane. ground metal exposed should wide possible better heat dissipation. Multiple vias ground plane under ground backplane) placed close exposed further reducing thermal resistance. (Pin Switching Regulator Error Amplifier Compensation. Connect resistor/capacitor network series with this pin. (Pin Error Amplifier Compensation Switcher Connect resistor/capacitor network series with this pin. (Pin Switching Regulator Feedback. resistor divider this VLOGIC according VLOGIC 1.25 R2/R1). Reference designators refer Figure (Pin Feedback Switch resistor divider this AVDD according AVDD 1.25 R6/R5). (Pin Switching Regulator Feedback. resistor divider this according 1.25 R9/R8) 150mV. NFB4 (Pin Switching Regulator Negative Feedback. Switcher used generate positive negative output. When regulating negative output, resistor divider this pin. Negative output voltage equation VOFF -1.25 (R3/R4) with 10k. NFB4 positive output voltages. (Pin Feedback Switch When generating positive voltage from switch resistor divider this pin. When generating negative voltage, resistor between NFB4 (R4). (Pin Switching Regulator Error Amplifier Compensation. Connect resistor/capacitor network series with this pin. (Pin 10): Switching Regulator Error Amplifier Compensation. Connect resistor/capacitor network series with this pin. SGND (Pin 11): Signal Ground. Return ground trace from resistor networks compensation components directly this then ground. BOOST (Pin 12): BOOST used provide drive voltage, higher than VIN, switch drive circuit. (Pins 14): pins emitter internal bipolar power transistor switching regulator These pins must tied together proper operation. Connect these pins inductor, catch diode boost capacitor. (Pins 16): pins supply current LT1943's internal regulator internal power transistor switch These pins must tied together locally bypassed. SS-234 (Pin 17): This soft-start switching regulators Place soft-start capacitor here limit start-up inrush current output voltage ramp rate. When BIAS reaches 2.8V, 1.7µA current source begins charging capacitor. When capacitor voltage reaches 0.8V, switches turn begin switching. slower start-up, larger capacitor. When this pulled ground, switches disabled. complete shutdown, RUN-SS ground. RUN-SS (Pin 18): This soft-start switching regulator Place soft-start capacitor here limit startup inrush current output voltage ramp rate. When power applied pin, 1.7µA current source charges capacitor. When voltage this reaches 0.8V, switch turns begins switching. slower start-up, larger capacitor. complete shutdown, RUN-SS ground. (Pin 19): This collector internal bipolar power transistor switching regulator Minimize metal trace area this keep down.
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LT1943
CTIO
(Pin 21): This collector internal bipolar power transistor switching regulator Minimize metal trace area this keep down. BIAS (Pin 22): BIAS used improve efficiency when operating higher input voltages. Connecting this output switching regulator forces most internal circuitry draw operating current from VLOGIC rather than VIN. Switches drivers supplied BIAS will switch until this reaches approximately 2.8V. BIAS must tied VLOGIC. PGOOD (Pin 23): Power Good Comparator Output. This open collector output power good comparator used conjunction with external P-Channel MOSFET provide output disconnect AVDD. When switcher output reaches approximately programmed voltage, PGOOD will pulled ground. This will pull down gate MOSFET, connecting AVDD. 100k pull-up resistor between source drain P-channel MOSFET keeps when switcher output low. (Pin 24): This switching regulator output emitter output disconnect PNP. output capacitor resistor divider here. (Pin 25): Timing Capacitor Pin. This input timer programs time delay from four feedback pins reaching 1.125V turning capacitor value using equation (20µA tDELAY)/1.1V. (Pin 26): This delayed output switching regulator reaches programmed voltage after internal timer times out. Protection circuitry ensures disabled four outputs more than below normal voltage. (Pins 28): pins collector internal bipolar power transistor switching regulator These pins must tied together. Minimize trace area these pins keep down.
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LT1943
BLOCK DIAGRA
VLOGIC AVDD PGOOD
MASTER OSCILLATOR 1.2MHz
20µA
1.125V
1.7µA RUN-SS INTERNAL REGULATOR REFERENCE
SS-234
1.7µA
LOCKOUT FOLDBACK OSCILLATOR
FOLDBACK OSCILLATOR
SLOPE COMPENSATION
BOOST
DRIVER SWITCH
VLOGIC
1.25V 1.25V
DRIVER 2.6A SWITCH
FOLDBACK OSCILLATOR 1.25V
BIAS
AVDD
SLOPE COMPENSATION
NFB4
DRIVER 400mA SWITCH VLOGIC VOFF
1.25V
BIAS
SLOPE COMPENSATION
2.8V
DRIVER 300mA SWITCH
1.25V
FOLDBACK OSCILLATOR
1.1V
SLOPE COMPENSATION
Figure
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LT1943
OPERATIO
LT1943 highly integrated power supply containing four separate switching regulators. four switchers have their oscillator with frequency foldback current mode control. Switching regulator consists step-down regulator with current limit 2.4A. Switching regulator boost regulator with current limit 2.6A switchers 0.35A boost regulators. Switching regulator feedback pins (FB4 NFB4) directly regulate positive negative output voltages. When power applied VIN, RUN-SS starts charging when voltage reaches 0.8V, switcher enabled. (See Figure RUN-SS used softstart limits ramp-rate VLOGIC. Using larger capacitor RUN-SS will cause VLOGIC start more slowly. Switching regulators driven BIAS which must connected VLOGIC. VLOGIC first come when reaches 2.8V, SS234 will begin charging enable switches AVDD VOFF will then begin rising their ramp rate determined capacitor tied SS-234 pin. When AVDD reaches approximately programmed voltage, PGOOD will pulled low. When outputs reach their programmed voltages, timer will trigger 20µA current source begins charge pin. When reaches 1.1V, output disconnect turns connecting VON. event outputs dropping below normal voltage, PanelProtect circuitry pulls ground, disabling VON. When needed, PGOOD used drive gate P-channel MOSFET that functions output disconnect AVDD. complete shutdown, RUN-SS must pulled ground.
RUN-SS 2V/DIV VLOGIC 5V/DIV 1A/DIV SS-234 2V/DIV AVDD 20V/DIV IL2+L3 1A/DIV PGOOD 20V/DIV 5ms/DIV
1943 F03a
(3a)
VOFF 10V/DIV 500mA/DIV 20V/DIV 500mA/DIV 2V/DIV 50V/DIV 5ms/DIV
1943 F03b
(3b) Figure LT1943 Power-Up Sequence. (Traces From Both Photos Synchronized Same Trigger)
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LT1943
PACKAGE DESCRIPTIO
Package 28-Lead Plastic TSSOP (4.4mm)
(Reference 05-08-1663)
Exposed Variation
4.75 (.187) 9.60 9.80* (.378 .386) 4.75 (.187) 2726 1716 6.60 ±0.10 4.50 ±0.10 NOTE 0.45 ±0.05
2.74 (.108)
EXPOSED HEAT SINK BOTTOM PACKAGE
2.74 6.40 (.108)
1.05 ±0.10 0.65 RECOMMENDED SOLDER LAYOUT 1.20 (.047)
4.30 4.50* (.169 .177)
0.09 0.20 (.0036 .0079)
0.45 0.75 (.018 .030)
0.65 (.0256)
0.195 0.30 (.0077 .0118)
0.05 0.15 (.002 .006)
FE28 (EB) TSSOP 0203
NOTE: CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS DIMENSIONS (INCHES) DRAWING SCALE
RECOMMENDED MINIMUM METAL SIZE EXPOSED ATTACHMENT *DIMENSIONS INCLUDE MOLD FLASH. MOLD FLASH SHALL EXCEED 0.150mm (.006") SIDE
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LT1943
TYPICAL APPLICATIO
VOFF -10V 50mA 2.2µF
ZHCS400
80.6k ZHCS400 0.47µF
10.0k
10pF BIAS BOOST CMDSH-3 0.22µF 4.7µH B230A
VLOGIC 3.3V 1.5A
16.2k
10.0k 22µF 27.4k 100pF 2.2nF
RELATED PARTS
PART NUMBER LT1615/LT1615-1 LT1940 LT1944/LT1944-1 LT1945 LT1946/LT1946A LT1947 LT3464 DESCRIPTION 300mA/80mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC Converters Dual Output 1.4A (IOUT), Constant 1.1MHz, High Efficiency Step-Down DC/DC Converter Dual Output 350mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC Converter Dual Output, Pos/Neg, 350mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC Converter 1.5mA (ISW), 1.2MHz/2.7MHz, High Efficiency Step-Up DC/DC Converter 1.1A, 3MHz, TFT-LCD Triple Output Switching Regulator COMMENTS VIN: 1.2V 15V, VOUT(MAX): 34V, 20µA, ISD: <1µA, ThinSOTPackage VIN: 25V, VOUT(MIN): 1.2V, 2.5mA, ISD: <1µA, TSSOP-16E Package VIN: 1.2V 15V, VOUT(MAX): 34V, 20µA, ISD: <1µA, Package VIN: 1.2V 15V, VOUT(MAX): ±34V, 20µA, ISD: <1µA, Package VIN: 2.75V 16V, VOUT(MAX): 34V, 20µA, ISD: <1µA, Package VIN: 2.7V VOUT(MAX): 34V, 9.5mA, ISD: <1µA, Package
85mA (ISW), Constant Off-Time, High Efficiency Step-Up DC/DC VIN: 2.3V 10V, VOUT(MAX): 34V, 25µA, ISD: <0.5µA, Converter with Integrated Schottky Output Disconnect ThinSOT Package
ThinSOT trademark Linear Technology Corporation.
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417
(408) 432-1900
FAX: (408) 434-0507 www.linear.com
Input, Quad Output TFT-LCD Power Supply
4.5V 10µH 10µF 33µH 10µF 95.3k NFB4 LT1943 RUN-SS SS-234 PGOOD 232k SGND 10.0k 2.2µF 0.015µF 0.015µF 0.047µF AVDD 500mA 30mA 10.0k FDN360P 100k 4.7µH B240A 6.81k 100pF 4700pF 30.1k 100pF 1500pF 100pF 2.2nF 0.47µF
1943
1943i LT/TP 0903 PRINTED
LINEAR TECHNOLOGY CORPORATION 2003
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