Datasheet LT3742 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual, 2-Phase Step-Down Switching Controller |
| Pages / Page | 26 / 1 — FeaTures. DescripTion. Wide Input Voltage Range: 4V to 30V. Wide Output … |
| File Format / Size | PDF / 319 Kb |
| Document Language | English |
FeaTures. DescripTion. Wide Input Voltage Range: 4V to 30V. Wide Output Voltage Range: 0.8V to VIN. Low Shutdown IQ: 20µA
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LT3742 Dual, 2-Phase Step-Down Switching Controller
FeaTures DescripTion
n
Wide Input Voltage Range: 4V to 30V
The LT®3742 is a dual step-down DC/DC switching regulator n
Wide Output Voltage Range: 0.8V to VIN
controller that drives high side N-channel power MOSFETs. n
Low Shutdown IQ: 20µA
A 500kHz fixed frequency current mode architecture pro- n
Out-of-Phase Controllers Reduce Required Input
vides fast transient response with simple loop compensa-
Capacitance and Power Supply Induced Noise
tion components and cycle-by-cycle current limiting. The n 0.8V ±1.5% Voltage Reference output stages of the two controllers operate 180° out of n 500kHz Current Mode Fixed Frequency Operation phase to reduce the input ripple current, minimizing the n Internal Boost Converter Provides Bias Rail for noise induced on the input supply, and allowing less input N-channel MOSFET Gate Drive capacitance. n Power Good Voltage Monitor for Each Output An internal boost regulator generates a bias rail of VIN + 7V n Programmable Soft-Start to provide gate drive for the N-channel MOSFETs allowing n 24-Lead 4mm × 4mm × 0.75mm Package low dropout and 100% duty cycle operation. The LT3742 can be used for applications where both controllers need
applicaTions
to operate independently, or where both controllers are used to provide a single higher current output. n Satellite and Cable TV Set-Top Boxes n Distributed Power Regulation The device is available in a thermally enhanced 4mm × n Automotive Systems 4mm QFN package. n L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and Burst Mode are registered Super Capacitor Charger trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion 8V and 5V Dual Step-Down Converter Efficiency vs Load Current
100 10µH 8VOUT VIN 4.7µF 14V 90 45.3k V 5V IN SWB BIAS OUT 1µF UVLO 80 20.0k 70 LT3742 V EFFICIENCY (%) IN VIN 60 10µF G1 G2 10µF 50 V 0.010Ω 6.5µH OUT1 6.5µH 0.010Ω VOUT2 8V SW1 SW2 5V 4A 40 1.8k SENSE1+ SENSE2+ 1.05k 4A SENSE1– SENSE2– 0 0.5 1 1.5 2 2.5 3 3.5 4 47µF FB1 FB2 47µF LOAD CURRENT (A) 200Ω 200Ω 3742 TA01b PG1 PG1 PG2 PG2 RUN/SS1 RUN/SS2 VC1 VC2 RUN1 30k 20k RUN2 1nF 1000pF GND 1000pF 1nF 3742 TA01a 3742fa 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Related Parts
FeaTures DescripTion
n
Wide Input Voltage Range: 4V to 30V
The LT®3742 is a dual step-down DC/DC switching regulator n
Wide Output Voltage Range: 0.8V to VIN
controller that drives high side N-channel power MOSFETs. n
Low Shutdown IQ: 20µA
A 500kHz fixed frequency current mode architecture pro- n
Out-of-Phase Controllers Reduce Required Input
vides fast transient response with simple loop compensa-
Capacitance and Power Supply Induced Noise
tion components and cycle-by-cycle current limiting. The n 0.8V ±1.5% Voltage Reference output stages of the two controllers operate 180° out of n 500kHz Current Mode Fixed Frequency Operation phase to reduce the input ripple current, minimizing the n Internal Boost Converter Provides Bias Rail for noise induced on the input supply, and allowing less input N-channel MOSFET Gate Drive capacitance. n Power Good Voltage Monitor for Each Output An internal boost regulator generates a bias rail of VIN + 7V n Programmable Soft-Start to provide gate drive for the N-channel MOSFETs allowing n 24-Lead 4mm × 4mm × 0.75mm Package low dropout and 100% duty cycle operation. The LT3742 can be used for applications where both controllers need
applicaTions
to operate independently, or where both controllers are used to provide a single higher current output. n Satellite and Cable TV Set-Top Boxes n Distributed Power Regulation The device is available in a thermally enhanced 4mm × n Automotive Systems 4mm QFN package. n L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and Burst Mode are registered Super Capacitor Charger trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Typical applicaTion 8V and 5V Dual Step-Down Converter Efficiency vs Load Current
100 10µH 8VOUT VIN 4.7µF 14V 90 45.3k V 5V IN SWB BIAS OUT 1µF UVLO 80 20.0k 70 LT3742 V EFFICIENCY (%) IN VIN 60 10µF G1 G2 10µF 50 V 0.010Ω 6.5µH OUT1 6.5µH 0.010Ω VOUT2 8V SW1 SW2 5V 4A 40 1.8k SENSE1+ SENSE2+ 1.05k 4A SENSE1– SENSE2– 0 0.5 1 1.5 2 2.5 3 3.5 4 47µF FB1 FB2 47µF LOAD CURRENT (A) 200Ω 200Ω 3742 TA01b PG1 PG1 PG2 PG2 RUN/SS1 RUN/SS2 VC1 VC2 RUN1 30k 20k RUN2 1nF 1000pF GND 1000pF 1nF 3742 TA01a 3742fa 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Related Parts
