LTC3735 2-Phase, High Efficiency DC/DC Controller for Intel Mobile CPUs FEATURES DESCRIPTION n Output Stages Operate Antiphase The LTC 3735 is a 2-phase synchronous step-down n 1% Output Voltage Accuracy switching regulator controller that drives all N-channel n 6-Bit IMVP-IV VID Code: V = 0.7V to 1.708V power MOSFETs in a constant frequency architecture. The OUT n Intel Compatible Power Saving Mode (PSIB) output voltage is programmable by six VID bits during n Stage Shedding Improves Low Current Efficiency normal operation and by external resistors during initial n Power Good Output with Adaptive Masking boot-up and deeper sleep state. The LTC3735 drives its two n Lossless Voltage Positioning output stages out-of-phase at frequencies up to 550kHz n Dual Input Supply Capability for Load Sharing to minimize the RMS ripple currents in both input and n Resistor Programmable V at Boot-Up and Deeper output capacitors. This antiphase technique also doubles OUT Sleep State the apparent switching frequency, improving the transient n Resistor Programmable Deep Sleep Offset response while operating each phase at an optimum fre- n Programmable Fixed Frequency: 210kHz to 550kHz quency for efficiency. Thermal design is further simplified n Adjustable Soft-Start Current Ramping by cycle-by-cycle current sharing between the two phases. n Foldback Output Current Limit An Intel compatible PSIB input is provided to select between n Short-Circuit Shutdown Timer with Defeat Option two modes of operation. Fully enhanced synchronous n Overvoltage Protection mode achieves a very small output ripple and very fast n Available in 36-Lead SSOP (0.209 Wide) and 38-Lead transient response while power saving mode realizes (5mm 7mm) Packages very high efficiency. OPTI-LOOP compensation allows the transient response to be optimized for a wide range APPLICATIONS of output capacitance and ESR values. n Mobile and Desktop Computers L, LT, LTC, LTM, OPTI-LOOP, PolyPhase, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their n Internet Servers respective owners. TYPICAL APPLICATION MCH PG TG1 M1 1H 0.002 DPRSLPVR SW1 STP CPUB PSIB V BG1 IN M2 D1 FREQSET 5V TO 24V PGND VID5-VID0 V OUT + 0.7V TO 1.708V PGOOD SENSE1 C C OUT 40A IN SENSE1 + I TH 330F 10F R C 2V 35V 100pF RUN/SS M3 TG2 4.74k 1H 0.002 5 4 232k C C 0.1F SW2 470pF SGND BG2 M4 D2 + V OA LTC3735 + SENSE2 4.5V TO 7V PV CC SENSE2 4.7F 13.3k 12.7k RBOOT BAT54A 56.2k BOOST1 RDPRSLP 1.27M BOOST2 RDPSLP 0.47F 0.47F + V + V OA OA 13.3k 549k OAOUT SW2 SW1 V OA 3735 F01 Figure 1. High Current 2-Phase Step-Down Converter 3735fa 1LTC3735 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (PV ) ....................... 7V to 0.3V Peak Gate Drive Current <1s CC Topside Driver Voltages (BOOST1,2) ......... 38V to 0.3V (TG1, TG2, BG1, BG2) .................................................5A Switch Voltage (SW1, 2) ............................... 32V to 5V Operating Ambient Temperature Range Boosted Driver Voltages (Note 2) ................................................... 40C to 85C (BOOST1-SW1, BOOST2-SW2) ............... 7V to 0.3V Junction Temperature (Note 3) ............................. 125C DPRSLPVR, STP CPUB, MCH PG, PGOOD, Storage Temperature Range RDPRSLP, RDPSLP, RBOOT Voltages ......... 5V to 0.3V SSOP ................................................. 65C to 150C RUN/SS, PSIB, FREQSET Voltages .............7V to 0.3V QFN .................................................... 65C to 125C VID0-VID5 Voltages ....................................5V to 0.3V QFN Reflow Peak Body Temperature .................... 260C V , Voltage ................................................ 2V to 0.3V Lead Temperature (Soldering, 10 sec) .................. 300C FB + V , V ............................................... 3.6V to 0.3V OA OA PIN CONFIGURATION TOP VIEW TOP VIEW 1 36 MCH PG V FB DPRSLPVR 2 35 PGOOD FREQSET 3 34 BOOST1 38 37 36 35 34 33 32 4 33 TG1 PSIB FREQSET 1 31 NC + V 5 32 SW1 PSIB 2 30 BOOST2 OA + 6 31 BOOST2 V 3 29 TG2 V OA OA V SW2 7 TG2 4 28 OAOUT 30 OA OAOUT 5 27 PV CC STP CPUB 8 29 SW2 STP CPUB 6 26 BG1 9 28 PV SGND CC 39 SGND 7 25 PGND + 10 BG1 SENSE1 27 + SENSE1 8 24 BG2 SENSE1 11 26 PGND SENSE1 9 23 VID5 + 12 25 BG2 SENSE2 + SENSE2 10 22 VID4 13 VID5 SENSE2 24 21 SENSE2 11 VID3 RDPRSLP 14 23 VID4 RDPRSLP 12 20 VID2 15 22 VID3 RDPSLP 13 14 15 16 17 18 19 RUN/SS 16 21 VID2 I 17 20 VID1 TH 18 19 VID0 RBOOT UHF PACKAGE 38-LEAD (7mm 5mm) PLASTIC QFN G PACKAGE T = 125C, = 34C/W JMAX JA 36-LEAD PLASTIC SSOP EXPOSED PAD (PIN 39) IS SIGNAL GROUND, MUST BE CONNECTED TO PCB AND SGND T = 125C, = 85C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3735EG PBF LTC3735EG TRPBF LTC3735 36-Lead Plastic SSOP 40C to 85C LTC3735EUHF PBF LTC3735EUHF TRPBF LTC3735 38-Lead (7mm 5mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. 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