POWER LOSS (mW) LTC3858 Low I , Dual Q 2-Phase Synchronous Step-Down Controller FEATURES DESCRIPTION n Low Operating I : 170A (One Channel On) The LTC 3858 is a high performance dual step-down Q n Wide Output Voltage Range: 0.8V V 24V switching regulator controller that drives all N-channel OUT n Wide V Range: 4V to 38V synchronous power MOSFET stages. A constant frequency IN n R or DCR Current Sensing current mode architecture allows a phase-lockable fre- SENSE n Out-of-Phase Controllers Reduce Required Input quency of up to 850kHz. Power loss and noise due to the Capacitance and Power Supply Induced Noise input capacitor ESR are minimized by operating the two n OPTI-LOOP Compensation Minimizes C controller outputs out of phase. OUT n Phase-Lockable Frequency (75kHz-850kHz) The 170A no-load quiescent current extends operating n Programmable Fixed Frequency (50kHz-900kHz) life in battery-powered systems. OPTI-LOOP compensa- n Selectable Continuous, Pulse-Skipping or tion allows the transient response to be optimized over Burst Mode Operation at Light Loads a wide range of output capacitance and ESR values. The n Very Low Dropout Operation: 99% Duty Cycle LTC3858 features a precision 0.8V reference and a power n Adjustable Output Voltage Soft-Start good output indicator. A wide 4V to 38V input supply range n Power Good Output Voltage Monitor encompasses a wide range of intermediate bus voltages n Output Overvoltage Protection and battery chemistries. n Output Latch-Off Protection During Short Circuit n Independent soft-start pins for each controller ramp the Low Shutdown I : 8A Q n output voltages during start-up. The output latch-off feature Internal LDO Powers Gate Drive from V or EXTV IN CC n protects the circuit in short-circuit conditions. No Current Foldback During Start-Up n Small 5mm 5mm QFN Package For a leaded 28-lead SSOP package with a xed current limit and one PGOOD output, without phase modulation APPLICATIONS or a clock output, see the LTC3858-1 data sheet. n Automotive Systems L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Module, PolyPhase, Linear Technology and the Linear logo are registered trademarks and No R and UltraFast are trademarks of Linear Technology SENSE n Battery Operated Digital Devices Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. n Distributed DC Power Systems TYPICAL APPLICATION High Ef ciency Dual 8.5V/3.3V Step-Down Converter V Ef ciency and Power Loss IN 9V TO 38V 22F vs Load Current 4.7F 50V V INTV 100 10000 IN CC TG1 TG2 90 0.1F 0.1F BOOST1 BOOST2 3.3H 7.2H 80 1000 EFFICIENCY SW1 SW2 70 BG1 BG2 60 100 LTC3858 POWER LOSS PGND 50 + + SENSE1 SENSE2 40 10 30 0.01 0.007 20 1 V SENSE1 SENSE2 OUT2 V OUT1 V = 12V IN 8.5V 3.3V V V FB1 FB2 10 V = 3.3V OUT 3.5A 5A 62.5k 193k FIGURE 12 CIRCUIT I I TH1 TH2 0 0.1 150F 680pF 680pF 150F SS1 SGND SS2 0.0001 0.001 0.01 0.1 1 10 20k 20k 15k 15k OUTPUT CURRENT (A) 0.1F 0.1F 3858 TA01b 3858 TA01 3858fc 1 EFFICIENCY (%)LTC3858 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Input Supply Voltage (V ) ......................... 0.3V to 40V IN Topside Driver Voltages BOOST1, BOOST2 ................................. 0.3V to 46V 32 31 30 29 28 27 26 25 Switch Voltage (SW1, SW2) ........................ 5V to 40V SENSE1 1 24 BOOST1 PLLIN/MODE,(BOOST1-SW1), FREQ 2 23 BG1 (BOOST2-SW2) ........................................... 0.3V to 6V PHASMD 3 22 V IN RUN1, RUN2 ............................................... 0.3V to 8V CLKOUT 4 21 PGND 33 SGND PLLIN/MODE 5 20 EXTV Maximum Current Sourced into Pin CC SGND INTV 6 19 CC from Source >8V...............................................100A + + RUN1 7 18 BG2 SENSE1 , SENSE2 , SENSE1 RUN2 8 17 BOOST2 SENSE2 Voltages ...................................... 0.3V to 28V 9 10 11 12 13 14 15 16 FREQ Voltages ..................................... 0.3V to INTV CC I , PHASMD Voltages ....................... 0.3V to INTV LIM CC EXTV ...................................................... 0.3V to 14V CC UH PACKAGE 32-LEAD (5mm s 5mm) PLASTIC QFN I , I ,V , V Voltages ...................... 0.3V to 6V TH1 TH2 FB1 FB2 T = 125C, = 34C/W JMAX JA PGOOD1, PGOOD2 Voltages ....................... 0.3V to 6V EXPOSED PAD (PIN 33) IS SGND, MUST BE SOLDERED TO PCB SS1, SS2, INTV Voltages ......................... 0.3V to 6V CC Operating Junction Temperature Range (Note 2) .................................................. 40C to 125C Maximum Junction Temperature (Note 3) ............ 125C Storage Temperature Range ................... 65C to 150C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3858EUH PBF LTC3858EUH TRPBF 3858 40C to 125C 32-Lead (5mm 5mm) Plastic QFN LTC3858IUH PBF LTC3858IUH TRPBF 3858 32-Lead (5mm 5mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: