LT3742 Dual, 2-Phase Step-Down Switching Controller Fea T Descrip T 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 V controller that drives high side N-channel power MOSFETs. IN n Low Shutdown I : 20A A 500kHz fixed frequency current mode architecture pro- Q 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 V + 7V IN 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 to operate independently, or where both controllers are a T used to provide a single higher current output. n Satellite and Cable TV Set-Top Boxes n The device is available in a thermally enhanced 4mm Distributed Power Regulation n 4mm QFN package. Automotive Systems n L, LT, LTC, LTM, Linear Technology, the Linear logo, PolyPhase and Burst Mode are registered Super Capacitor Charger trademarks and No R is a trademark of Linear Technology Corporation. All other SENSE trademarks are the property of their respective owners. Typical a T 8V and 5V Dual Step-Down Converter Efficiency vs Load Current 100 8V 10H OUT V 4.7F IN 14V 90 45.3k 5V OUT V SWB BIAS IN 1F 80 UVLO 20.0k 70 LT3742 60 V V IN IN 10F 10F G1 G2 50 6.5H 6.5H V 0.010 0.010 V OUT1 OUT2 8V SW1 SW2 5V + + 4A SENSE1 SENSE2 4A 40 1.8k 1.05k 0 0.5 1 1.5 2 2.5 3 3.5 4 SENSE1 SENSE2 47F FB1 FB2 47F LOAD CURRENT (A) 3742 TA01b 200 200 PG1 PG1 PG2 PG2 RUN/SS1 RUN/SS2 V V C1 C2 30k 20k RUN1 RUN2 GND 1nF 1nF 1000pF 1000pF 3742 TA01a 3742fa 1 EFFICIENCY (%) ion pplica ions pplica ion uresLT3742 a Te Maxi Mu M r a T p F T (Note 1) V Voltage ................................................................30V TOP VIEW IN UVLO Voltage ............................................................30V PG1, PG2 Voltage ......................................................30V 24 23 22 21 20 19 SWB, BIAS Voltage ...................................................40V + + G1 1 18 V SENSE1 , SENSE2 Voltage ......................................30V C1 V PG1 2 17 IN SENSE1 , SENSE2 Voltage ......................................30V UVLO 3 16 RUN/SS1 RUN/SS1, RUN/SS2 Voltage .......................................6V 25 BIAS 4 15 RUN/SS2 FB1, FB2 Voltage .........................................................6V SWB 5 14 PG2 V , V Voltage ..........................................................6V C1 C2 G2 6 13 V C2 Junction Temperature ........................................... 125C 7 8 9 10 11 12 Operating Junction Temperature Range (Note 2) .................................................. 40C to 125C Storage Temperature Range .................. 65C to 125C UF PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN T = 125C, = 36C/W JMAX JA EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB Der in F Ma T LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT3742EUF PBF LT3742EUF TRPBF 3742 24-Lead (4mm 4mm) Plastic QFN 40C to 125C (Note 2) Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: