LTC3859A Low I , Triple Output, Q Buck/Buck/Boost Synchronous Controller with Improved Burst Mode Operation Fea T Descrip T n Dual Buck Plus Single Boost Synchronous Controllers The LTC 3859A is a high performance triple output (buck/ n Outputs Remain in Regulation Through Cold Crank buck/boost) synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Down to 2.5V n Constant frequency current mode architecture allows Low Operating I : 55A (One Channel On) Q a phase-lockable switching frequency of up to 850kHz. n Wide Bias Input Voltage Range: 4.5V to 38V The LTC3859A operates from a wide 4.5V to 38V input n Buck Output Voltage Range: 0.8V V 24V OUT supply range. When biased from the output of the boost n Boost Output Voltage Up to 60V converter or another auxiliary supply, the LTC3859A 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 Even in Burst Mode Operation The 55A no-load quiescent current extends operating n runtime in battery powered systems. OPTI-LOOP com- Phase-Lockable Frequency (75kHz to 850kHz) n pensation allows the transient response to be optimized Programmable Fixed Frequency (50kHz to 900kHz) over a wide range of output capacitance and ESR values. n Selectable Continuous, Pulse-Skipping or Low Ripple The LTC3859A features a precision 0.8V reference for the Burst Mode Operation at Light Loads bucks, 1.2V reference for the boost and a power good n Very Low Buck Dropout Operation: 99% Duty Cycle output indicator. The PLLIN/MODE pin selects among n Adjustable Output Voltage Soft-Start or Tracking Burst Mode operation, pulse-skipping mode, or continu- n Low Shutdown I : 14A Q ous inductor current mode at light loads. n Small 38-Pin 5mm 7mm QFN and TSSOP Packages Compared to the LTC3859, the LTC3859A s boost controller a T has improved performance in Burst Mode operation when n Automotive Always-On and Start-Stop Systems the input voltage is higher than the regulated output voltage. n Battery Operated Digital Devices L, LT, LTC, LTM, Burst Mode, OPTI-LOOP and Module are registered trademarks and No R is a trademark of Linear Technology Corporation. All other trademarks are the SENSE n Distributed DC Power Systems property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258. n Multioutput Buck-Boost Applications Typical a T V OUT3 REGULATED AT 10V WHEN V < 10V IN 220F 1F FOLLOWS V WHEN V > 10V IN IN 499k Efficiency vs Input Voltage V BIAS V FB3 100 68.1k TG1 4.9H V V = 8.5V 6m OUT1 95 OUT2 TG3 SW1 5V 1.2H V 2m IN 90 V = 5V 5A OUT1 2.5V TO 38V SW3 BG1 LTC3859A (START-UP ABOVE 5V) 85 220F BG3 80 + SENSE1 75 SENSE3 SENSE1 + SENSE3 V 70 FB1 357k INTV CC 65 68.1k 220F RUN1, 2, 3 4.7F 60 BOOST1, 2, 3 EXTV V CC OUT1 FIGURE 12 CIRCUIT 55 0.1F SW1, 2, 3 I = 2A LOAD TG2 V 6.5H 50 8m OUT2 0 5 10 15 20 25 30 35 40 I SW2 8.5V TH1, 2, 3 3A INPUT VOLTAGE (V) BG2 3859A TA01b SENSE2+ TRACK/SS1, 2 SENSE2 0.1F SS3 V FB2 649k PGND SGND 68.1k 68F 3859 TA01a 3859afa 1 EFFICIENCY (%) ion pplica ions pplica ion uresLTC3859A a Te Maxi Mu M r a T (Notes 1, 3) + + 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 76V 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 70V PLLIN/MODE, PGOOD1, OV3 Voltages ........ 0.3V to 6V , (BOOST1SW1), TRACK/SS1, TRACK/SS2, SS3 Voltages ..... 0.3V to 6V INTV CC (BOOST2SW2), (BOOST3SW3), .......... 0.3V to 6V Operating Junction Temperature Range (Note 2) RUN1, RUN2, RUN3 .................................... 0.3V to 8V LTC3859AE, LTC3859AI..................... 40C to 125C Maximum Current Sourced Into Pin LTC3859AH........................................ 40C to 150C from Source >8V ..............................................100A LTC3859AMP ..................................... 55C to 150C Storage Temperature Range .............. 65C to 150C p in c F T TOP VIEW TOP VIEW 1 38 TRACK/SS1 I TH1 2 37 PGOOD1 V FB1 + 3 36 TG1 SENSE1 38 37 36 35 34 33 32 4 35 SW1 SENSE1 FREQ 1 31 SW1 5 34 BOOST1 FREQ PLLIN/MODE 2 30 BOOST1 6 33 BG1 PLLIN/MODE SS3 3 29 BG1 7 32 SW3 SS3 + SENSE3 4 28 SW3 + 8 31 TG3 SENSE3 SENSE3 5 27 TG3 9 30 BOOST3 SENSE3 V 6 26 BOOST3 FB3 39 39 10 29 BG3 V FB3 PGND PGND I 7 25 BG3 TH3 11 28 V I TH3 BIAS SGND 8 24 V BIAS 12 27 EXTV SGND CC RUN1 9 23 EXTV CC 13 26 INTV RUN1 CC RUN2 10 22 INTV CC 14 25 BG2 RUN2 21 RUN3 11 BG2 15 24 BOOST2 RUN3 SENSE2 12 20 BOOST2 16 23 SW2 SENSE2 13 14 15 16 17 18 19 + 17 22 TG2 SENSE2 18 21 OV3 V FB2 19 20 TRACK/SS2 I TH2 UHF PACKAGE FE PACKAGE 38-LEAD (5mm 7mm) PLASTIC QFN 38-LEAD PLASTIC TSSOP T = 150C, q = 34.7C/W JMAX JA T = 150C, q = 25C/W EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB JMAX JA EXPOSED PAD (PIN 39) IS PGND, MUST BE SOLDERED TO PCB 3859afa 2 + SENSE1 SENSE2 + V SENSE1 FB2 I V TH2 FB1 TRACK/SS2 I TH1 OV3 TRACK/SS1 PGOOD1 TG2 SW2 TG1 ion igura on ings bsolu