POWER LOSS (mW) LTC7815 Low I , 2.25MHz, Q Triple Output, Buck/Buck/Boost Synchronous Controller FEATURES DESCRIPTION n Dual Buck Plus Single Boost Synchronous Controllers The LTC 7815 is a high performance triple output (buck/ n buck/boost) synchronous DC/DC switching regulator con- Wide Bias Input Voltage Range: 4.5V to 38V n troller that drives all N-channel power MOSFET stages. Outputs Remain in Regulation Through Cold Crank Constant frequency current mode architecture allows a Down to a 2.5V Input Supply Voltage phase-lockable switching frequency of up to 2.25MHz. n Buck Output Voltage Range: 0.8V V 24V OUT The LTC7815 operates from a wide 4.5V to 38V input n Boost Output Voltage Up to 60V supply range. When biased from the output of the boost n Low Operating I : 28A (One Channel On) Q converter or another auxiliary supply, the LTC7815 can n R or DCR Current Sensing SENSE operate from an input supply as low as 2.5V after start-up. n 100% Duty Cycle for Boost Synchronous MOSFET The 28A no-load quiescent current extends operating Even in Burst Mode Operation n runtime in battery powered systems. OPTI-LOOP com- Phase-Lockable Frequency (320kHz to 2.25MHz) n pensation allows the transient response to be optimized Programmable Fixed Frequency (320kHz to 2.25MHz) over a wide range of output capacitance and ESR values. n Very Low Buck Dropout Operation: 98% Duty Cycle The LTC7815 features a precision 0.8V reference for the n Small 38-Lead 5mm 7mm QFN Package bucks, 1.2V reference for the boost and a power good output indicator. The PLLIN/MODE pin selects among APPLICATIONS Burst Mode operation, pulse-skipping mode, or continu- n Automotive Always-On and Start-Stop Systems ous inductor current mode at light loads. n Battery Operated Digital Devices All registered trademarks and trademarks are the property of their respective owners. Protected n Distributed DC Power Systems by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Multioutput Buck-Boost Applications TYPICAL APPLICATION V OUT3 Efficiency and Power Loss vs REGULATED AT 10V WHEN V < 10V IN FOLLOWS V WHEN V > 10V IN IN 10F Output Current 499k 68F 5 + V BIAS V 100 10k FB3 V = 12V IN 68.1k TG1 90 V = 5V OUT1 0.33H V 3m OUT1 80 1k TG3 SW1 5V 3m 0.16H V 7A IN 70 SW3 2.5V TO 28V BG1 LTC7815 (START-UP ABOVE 5V) 60 100 220F + BG3 + 50 SENSE1 SENSE3 SENSE1 10 40 + SENSE3 V FB1 30 C OUT1 357k INTV f = 2.1MHz 10F CC 68.1k 47F 20 1 2 4.7F 2 Burst Mode OPERATION BOOST1, 2, 3 EXTV V 10 CC OUT1 BURST LOSS 0.1F 0 0.1 SW1, 2, 3 TG2 0.0001 0.001 0.01 0.1 1 10 0.33H V 3m OUT2 3.3V I SW2 LOAD CURRENT (A) TH1, 2, 3 7815 TA01b 10A BG2 + SENSE2 SENSE2 TRACK/SS1, 2 0.1F V SS3 FB2 C OUT2 210k 68.1k 33F RUN1 2 RUN2 100k FREQ RUN3 PGND SGND 7815 TA01a 7815f 1 For more information www.linear.com/LTC7815 EFFICIENCY (%)LTC7815 ABSOLUTE MAXIMUM RATINGS (Note 1) + + Bias Input Supply Voltage (V ) .............. 0.3V to 40V SENSE1 , SENSE2 , SENSE1 BIAS Buck Top Side Driver Voltages SENSE2 Voltages ................................. 0.3V to 28V + (BOOST1, BOOST2) ............................. 0.3V to 46V SENSE3 , SENSE3 Voltages ..................... 0.3V to 40V Boost Top Side Driver Voltages FREQ Voltages ......................................0.3V to INTV CC (BOOST3) ............................................ 0.3V to 71V EXTV ...................................................... 0.3V to 14V CC Buck Switch Voltage (SW1, SW2) ................ 5V to 40V I , I , I , V , V , V Voltages .... 0.3V to 6V TH1 TH2 TH3 FB1 FB2 FB3 Boost Switch Voltage (SW3) ........................5V to 65V PLLIN/MODE, PGOOD1, OV3 Voltages ........ 0.3V to 6V INTV , (BOOST1SW1), TRACK/SS1, TRACK/SS2, SS3 Voltages ..... 0.3V to 6V CC (BOOST2SW2), (BOOST3SW3) ........... 0.3V to 6V Operating Junction Temperature Range (Notes 2, 3) BG1, BG2, BG3, TG1, TG2, TG3 ...................... (Note 8) LTC7815E, LTC7815I .......................... 40C to 125C RUN1, RUN2, RUN3 .................................... 0.3V to 8V LTC7815H .......................................... 40C to 150C Maximum Current Sourced Into Pin Storage Temperature Range .............. 65C to 150C from Source >8V ..............................................100A PIN CONFIGURATION TOP VIEW 38 37 36 35 34 33 32 FREQ 1 31 SW1 PLLIN/MODE 2 30 BOOST1 SS3 3 29 BG1 + SENSE3 SW3 4 28 SENSE3 TG3 5 27 V 6 26 BOOST3 FB3 39 PGND I 7 25 BG3 TH3 SGND 8 24 V BIAS RUN1 9 23 EXTV CC RUN2 22 INTV 10 CC RUN3 11 21 BG2 SENSE2 12 20 BOOST2 13 14 15 16 17 18 19 UHF PACKAGE 38-LEAD (5mm 7mm) PLASTIC QFN T = 150C, q = 34.7C/W, q = 2C/W JMAX JA JC EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB 7815f 2 For more information www.linear.com/LTC7815 + SENSE2 SENSE1 + V SENSE1 FB2 I V FB1 TH2 TRACK/SS2 I TH1 OV3 TRACK/SS1 TG2 PGOOD1 SW2 TG1