LTC1628-SYNC High Efficiency, 2-Phase Synchronous Step-Down Switching Regulator FEATURES DESCRIPTIO Out-of-Phase Controllers Reduce Required Input The LTC 1628-SYNC is a high performance dual step- down switching regulator controller that drives all Capacitance and Power Supply Induced Noise N-channel synchronous power MOSFET stages. A con- OPTI-LOOP Compensation Minimizes C OUT stant frequency current mode architecture allows phase- Dual N-Channel MOSFET Synchronous Drive lockable frequency of up to 300kHz. Power loss and noise 1% Output Voltage Accuracy due to the ESR of the input capacitors are minimized by Power Good Output Voltage Monitor operating the two controller output stages out of phase. Phase-Lockable Fixed Frequency 150kHz to 300kHz Wide V Range: 3.5V to 36V Operation IN OPTI-LOOP compensation allows the transient response Very Low Dropout Operation: 99% Duty Cycle to 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 microproces- Latched Short-Circuit Shutdown with Defeat Option sor generations, and a wide 3.5V to 30V (36V maximum) Output Overvoltage Protection input supply range 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 or Burst Mode conditions when overcurrent latchoff is disabled. Output Operation overvoltage protection circuitry latches on the bottom Small 28-Lead SSOP Package MOSFET until V returns to normal. The FCB mode pin OUT U can select among Burst Mode, constant frequency mode APPLICATIO S and continuous inductor current mode or regulate a Notebook and Palmtop Computers, PDAs secondary winding. Telecom Systems , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation. Battery-Operated Digital Devices All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5929620, 6177787, 6144194, 6100678, 5408150, 6580258, 6304066, DC Power Distribution Systems 5705919. TYPICAL APPLICATIO V IN 5.2V TO 28V C IN + 1F 22F 4.7F D3 CERAMIC 50V D4 V PGOOD INTV IN CC CERAMIC M1 M3 TG1 TG2 L1 L2 C , 0.1F B2 BOOST1 BOOST2 6.3H 6.3H C , 0.1F B1 SW1 SW2 LTC1628-SYNC M2 M4 BG1 BG2 D1 D2 f PLLIN PGND IN + + 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 OUT1 C 1% 1% OUT + R1 RUN/SS1 SGND RUN/SS2 R3 220pF 220pF 47F 56F 20k 20k 6V R R C1 C C C2 6V SS1 SS2 1% 1% SP 15k 15k 0.1F 0.1F SP M1, M2, M3, M4: FDS6680A 1628 F01 Figure 1. High Efficiency Dual 5V/3.3V Step-Down Converter 1628syncfa 1 + U ULTC1628-SYNC UUW ABSOLUTE AXI U RATI GS PACKAGE/ORDER I FOR ATIO (Note 1) TOP VIEW Input Supply Voltage (V ).........................36V to 0.3V IN 1 28 PGOOD RUN/SS1 Top Side Driver Voltages + SENSE1 2 27 TG1 (BOOST1, BOOST2) ...................................42V to 0.3V SENSE1 3 26 SW1 Switch Voltage (SW1, SW2) .........................36V to 5V 4 25 BOOST1 V OSENSE1 5 24 V PLLFLTR IN INTV EXTV , RUN/SS1, RUN/SS2, (BOOST1-SW1), CC, CC PLLIN 6 23 BG1 (BOOST2-SW2), PGOOD .............................7V to 0.3V 7 EXTV FCB 22 CC + + SENSE1 , SENSE2 , SENSE1 , 8 21 INTV I CC TH1 SENSE2 Voltages........................ (1.1)INTV to 0.3V CC SGND 9 20 PGND PLLIN, PLLFLTR, FCB, Voltage ............ INTV to 0.3V 10 BG2 3.3V 19 CC OUT 11 18 BOOST2 I I I , V , V Voltages ...2.7V to 0.3V TH2 TH1, TH2 OSENSE1 OSENSE2 V 12 17 SW2 OSENSE2 Peak Output Current <10s (TG1, TG2, BG1, BG2) ... 3A SENSE2 13 16 TG2 INTV Peak Output Current ................................ 50mA CC + 14 15 RUN/SS2 SENSE2 Operating Temperature Range G PACKAGE LTC1628CG-SYNC................................... 0C to 85C 28-LEAD PLASTIC SSOP T = 125C, = 95C/W JMAX JA LTC1628IG-SYNC ............................... 40C to 85C *PGOOD ON THE LTC1628-SYNC Junction Temperature (Note 2)............................. 125C ORDER PART NUMBER Storage Temperature Range ................. 65C to 150C Lead Temperature (Soldering, 10 sec).................. 300C LTC1628CG-SYNC LTC1628IG-SYNC Order Options Tape and Reel: Add TR Lead Free: Add PBF Lead Free Tape and Reel: Add TRPBF Lead Free Part Marking: