LTC3707 High Ef ciency, 2-Phase Synchronous Step-Down Switching Regulator FEATURES DESCRIPTION 180 Phased Dual Controllers Reduce Required The LTC 3707 is a high performance dual step-down Input Capacitance and Power Supply Induced Noise switching regulator controller that drives N-channel OPTI-LOOP Compensation Minimizes C synchronous power MOSFET stages. A constant frequency OUT 1.5% Output Voltage Accuracy over Temperature current mode architecture allows adjustment of the Dual N-Channel MOSFET Synchronous Drive frequency up to 300kHz. Power loss and noise due to the Power Good Output Voltage Monitor ESR of the input capacitors are minimized by operating DC Programmed Fixed Frequency 150kHz to 300kHz the two controller output stages out of phase. Wide V Range: 4.5V to 28V Operation IN OPTI-LOOP compensation allows the transient response to Very Low Dropout Operation: 99% Duty Cycle be optimized over a wide range of output capacitance and Adjustable Soft-Start Current Ramping ESR values. The precision 0.8V reference and power good Foldback Output Current Limiting output indicator are compatible with future microprocessor Latched Short-Circuit Shutdown with Defeat Option generations, and a wide 3.5V to 30V input supply range Output Overvoltage Protection encompasses all battery chemistries. Remote Output Voltage Sense A RUN/SS pin for each controller provides both soft-start Low Shutdown I : 20A Q and optional timed, short-circuit shutdown. Current 5V and 3.3V Standby Regulators foldback limits MOSFET dissipation during short-circuit Selectable Constant Frequency, Burst Mode conditions when overcurrent latchoff is disabled. Output Operation or PWM Operation overvoltage protection circuitry latches on the bottom Small 28-Lead Narrow SSOP Package MOSFET until V returns to normal. The FCB mode OUT APPLICATIONS pin can select among Burst Mode operation, constant Notebook and Palmtop Computers, PDAs frequency mode and continuous inductor current mode Battery Chargers or regulate a secondary winding. Portable Instruments L, LT, LTC, LTM, Burst Mode, and OPTI-LOOP are registered trademarks of Linear Technology Battery-Operated Digital Devices Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6304066, 6580258. DC Power Distribution Systems V IN 5.2V TO 28V TYPICAL APPLICATION C IN + 1F 22F 4.7F D3 CERAMIC D4 50V V INTV IN CC CERAMIC M1 TG1 TG2 M3 L1 C , 0.1F C , 0.1F L2 B1 B2 6.3H BOOST1 BOOST2 6.3H SW1 SW2 LTC3707 M2 BG1 BG2 M4 D1 D2 SGND PGND + + SENSE1 SENSE2 R R SENSE1 SENSE2 1000pF 1000pF 0.01 0.01 SENSE1 SENSE2 V V OUT1 OUT2 5V 3.3V V V OSENSE1 OSENSE2 5A R2 5A R4 I I TH1 TH2 105k 63.4k C C C C1 C2 C OUT1 1% OUT 1% + R1 RUN/SS1 RUN/SS2 R3 220pF 220pF 47F 56F 20k 20k 6V R R C1 C C C2 6V SS1 SS2 1% 1% 15k 15k SP 0.1F 0.1F SP M1, M2, M3, M4: FDS6680A 3707 F01 Figure 1. High Ef ciency Dual 5V/3.3V Step-Down Converter 3707fb 1 +LTC3707 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Input Supply Voltage (V ) .........................30V to 0.3V IN RUN/SS1 1 28 PGOOD Top Side Driver Voltages + SENSE1 2 27 TG1 (BOOST1, BOOST2) ................................... 36V to 0.3V SENSE1 3 26 SW1 Switch Voltage (SW1, SW2) ......................... 30V to 5V V 4 25 BOOST1 OSENSE1 INTV EXTV , RUN/SS1, RUN/SS2, (BOOST1-SW1), CC, CC FREQSET 5 24 V IN (BOOST2-SW2), PGOOD .............................. 7V to 0.3V STBYMD 6 23 BG1 + + SENSE1 , SENSE2 , SENSE1 , FCB 7 22 EXTV CC SENSE2 Voltages .........................(1.1)INTV to 0.3V CC I 8 21 INTV CC TH1 FREQSET, STBYMD, FCB Voltage ......... INTV to 0.3V SGND 9 20 PGND CC I I , V , V Voltages ... 2.7V to 0.3V 3.3V 10 19 BG2 TH1, TH2 OSENSE1 OSENSE2 OUT I 11 18 BOOST2 Peak Output Current <10s (TG1, TG2, BG1, BG2) .....3A TH2 V 12 17 SW2 INTV Peak Output Current ................................. 40mA OSENSE2 CC SENSE2 13 16 TG2 Operating Temperature Range (Note 2).... 40C to 85C + SENSE2 14 15 RUN/SS2 Junction Temperature (Note 3) ............................. 125C Storage Temperature Range ................... 65C to 150C GN PACKAGE 28-LEAD PLASTIC SSOP Lead Temperature (Soldering, 10 sec) .................. 300C T = 125C, = 95C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3707EGN PBF LTC3707EGN TRPBF 3707EGN 28-Lead Plastic SSOP 40C to 85C LTC3707IGN PBF LTC3707IGN TRPBF 3707IGN 28-Lead Plastic SSOP 40C to 85C LEAD BASED FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3707EGN LTC3707EGN TR 3707EGN 28-Lead Plastic SSOP 40C to 85C LTC3707IGN LTC3707IGN TR 3707IGN 28-Lead Plastic SSOP 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. For more information on lead free part marking, go to: