POWER LOSS (mW) LTC3858-1 Low I , Dual Q 2-Phase Synchronous Step-Down Controller FEATURES DESCRIPTION n Low Operating I : 170A (One Channel On) The LTC 3858-1 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 LTC3858-1 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 Latchoff 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 Latchoff 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 Tiny 4mm 5mm QFN and Narrow SSOP Packages For a leadless 32-pin QFN package with the additional fea- tures of adjustable current limit, clock out, phase modula- APPLICATIONS tion and two PGOOD outputs, see the LTC3858 data sheet. n Automotive Systems L, LT, LTC, LTM, Burst Mode, OPTI-LOOP, Module, 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. n Patents, including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258. Distributed DC Power Systems TYPICAL APPLICATION High Ef ciency Dual 8.5V/3.3V Step-Down Converter V IN Ef ciency and Power Loss 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 SW1 SW2 70 EFFICIENCY BG1 BG2 60 100 LTC3858-1 PGND 50 POWER LOSS + + SENSE1 40 10 SENSE2 30 0.007 0.01 20 1 V V SENSE1 SENSE2 OUT2 OUT1 V = 12V IN 8.5V 3.3V V V 10 V = 3.3V FB1 FB2 OUT 3.5A 5A 62.5k 193k I I FIGURE 12 CIRCUIT TH1 TH2 0 0.1 150F 680pF 680pF 150F SS1 SGND SS2 0.0001 0.001 0.01 0.1 1 10 20k OUTPUT CURRENT (A) 20k 15k 15k 0.1F 0.1F 38581 TA01b 38581 TA01 38581fd 1 EFFICIENCY (%)LTC3858-1 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Supply Voltage (V ) ......................... 0.3V to 40V EXTV ...................................................... 0.3V to 14V IN CC Topside Driver Voltages I , I ,V , V Voltages ...................... 0.3V to 6V TH1 TH2 FB1 FB2 BOOST1, BOOST2 ................................. 0.3V to 46V PGOOD1 Voltage ......................................... 0.3V to 6V Switch Voltage (SW1, SW2) ........................ 5V to 40V SS1, SS2, INTV Voltages ......................... 0.3V to 6V CC (BOOST1-SW1), (BOOST2-SW2) ................ 0.3V to 6V Operating Junction Temperature Range RUN1, RUN2 ............................................... 0.3V to 8V (Note 2) .................................................. 40C to 125C Maximum Current Sourced Into Pin Maximum Junction Temperature (Note 3) ............ 125C from Source >8V...............................................100A Storage Temperature Range ................... 65C to 150C + + SENSE1 , SENSE2 , SENSE1 Lead Temperature (Soldering, 10 sec) SENSE2 Voltages ...................................... 0.3V to 28V SSOP ................................................................300C PLLIN/MODE, FREQ Voltages .............. 0.3V to INTV CC PIN CONFIGURATION TOP VIEW TOP VIEW I 1 28 SS1 TH1 V 2 27 PGOOD1 FB1 + 28 27 26 25 24 23 SENSE1 3 26 TG1 + SENSE1 1 22 BOOST1 SENSE1 4 25 SW1 SENSE1 2 21 BG1 FREQ 5 24 BOOST1 FREQ 3 20 V IN PLLIN/MODE 6 23 BG1 PLLIN/MODE 4 19 PGND 29 SGND 7 22 V IN SGND SGND 5 18 EXTV CC RUN1 8 21 PGND RUN1 6 17 INTV CC RUN2 9 20 EXTV CC RUN2 7 16 BG2 SENSE2 10 19 INTV CC SENSE2 8 15 BOOST2 + SENSE2 11 18 BG2 9 10 11 12 13 14 V 12 17 BOOST2 FB2 I 13 16 SW2 TH2 SS2 14 15 TG2 UFD PACKAGE 28-LEAD (4mm s 5mm) PLASTIC QFN GN PACKAGE 28-LEAD PLASTIC SSOP T = 125C, = 43C/W JMAX JA EXPOSED PAD (PIN 29) IS SGND, MUST BE SOLDERED TO PCB T = 125C, = 90C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3858EUFD-1 PBF LTC3858EUFD-1 TRPBF 38581 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3858IUFD-1 PBF LTC3858IUFD-1 TRPBF 38581 28-Lead (4mm 5mm) Plastic QFN 40C to 125C LTC3858EGN-1 PBF LTC3858EGN-1 TRPBF LTC3858GN-1 28-Lead Plastic SSOP 40C to 125C LTC3858IGN-1 PBF LTC3858IGN-1 TRPBF LTC3858GN-1 28-Lead Plastic SSOP 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: