POWER LOSS (mW) LTC3608 18V, 8A Monolithic Synchronous Step-Down DC/DC Converter Fserutae Dnoitpircse n 8AOutput Current The LTC 3608 is a high efcfi iency, monolithic synchronous n WideV Range= 4V to 18V step-down DC/DC converter that can deliver up to 8A output IN n InternalN-Channel MOSFET s current from a 4V to 18V (20V maximum) input supply. It n TrueCurrent Mode Control uses a valley current control architecture to deliver very n Optimized forHigh Step-Down Ratios low duty cycle operation at high frequency with excellent n t 100nsec transient response. The operating frequency is selected ON(MIN) n ExtremelyFast T ransientResponse by an external resistor and is compensated for variations n Stable with Ceramic C in V and V . OUT IN OUT n 1%0.6V V oltageReference The LTC3608 can be configured for discontinuous or n Power Good Output Voltage Monitor forced continuous operation at light load. Forced continu- n Adjustable On-Time/Switching Frequency ous operation reduces noise and RF interference while n Adjustable Current Limit discontinuous mode provides high efficiency by reducing n Programmable Soft-Start switching losses at light loads. n Output Overvoltage Protection n Fault protection is provided by internal foldback current Optional Short-Circuit Shutdown Timer n limiting, an output overvoltage comparator and an optional Low Shutdown I : 15A Q n short-circuit shutdown timer. Soft-start capability for sup- Available in a 7mm 8mm 52-Lead QFN Package ply sequencing is accomplished using an external timing a snoitacilpp capacitor. The regulator current limit is user programmable. A power good output voltage monitor indicates when n Point of Load Regulation the output is in regulation. The LTC3608 is available in a n Distributed Power Systems compact 7mm 8mm QFN package. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 6100678, 6580258, 5847554, 6304066. t lacipy a noitacilpp Efficiencyand Power Loss High EfficiencyStep-Down Converter vs LoadCurrent 187k V V I 100 10000 0.1F OUT ON ON V IN 95 RUN/SS V IN EFFICIENCY 4V TO 18V 10F 90 100pF LTC3608 3 1000 85 0.8H V OUT SW 2.5V 80 1500pF 8A 0.22F 100F 75 100 I BOOST 2 TH 70 11.3k POWER LOSS 65 SGND INTV CC 10 30.1k 60 FCB V = 12V IN V = 2.5V OUT 55 4.7F V RNG EXTV = 5V CC PGND 50 1 PGOOD 0.01 0.1 1 10 EXTV V CC LOAD CURRENT (A) FB 3608 TA01b 9.53k 3608 TA01a 3608fc EFFICIENCY (%)LTC3608 a etulosbMixa Mu M r sgnita p ni noc Fnoitarugi (Note 1) TOP VIEW Input Supply Voltage (SV , PV , I ) ....... 20V to 0.3V IN IN ON Boosted Topside Driver Supply Voltage (BOOST) ................................................ 26V to 0.3V SW Voltage ............................................ 20V to 0.3V PV 1 40 PGND IN INTV , EXTV , (BOOST SW), RUN/SS, PV 2 39 PGND IN CC CC PV 3 38 PGND IN PGOOD Voltages ...................................... 7V to 0.3V 53 PV 4 37 PGND IN PV 55 IN FCB, V , V Voltages ............ INTV + 0.3V to 0.3V SW ON RNG CC PV 5 36 PGND IN PV 6 35 PGND I , V Voltages ....................................... 2.7V to 0.3V IN TH FB PV 7 34 PGND IN Operating Junction Temperature Range SW 8 33 SW (Notes 2, 4) ........................................ 40C to 125C NC 9 32 INTV CC SGND 10 31 INTV Storage Temperature Range ................... 55C to 125C CC BOOST 11 30 SV IN 54 RUN/SS 12 29 EXTV SGND CC V 13 28 NC ON SGND 14 27 SGND WKG PACKAGE 52-LEAD (7mm 8mm) QFN MULTIPAD T = 125C, = 29C/W JMAX JA o r D re i n Fro Mnoita LEAD FREE FINISH TAPE AND REEL PART MARKING * PACKAGE DESCRIPTION TEMPERATURERANGE LTC3608EWKG PBF LTC3608EWKG TRPBF LTC3608WKG 52-Lead (7mm 8mm) Plastic QFN 40C to 125C LTC3608IWKG PBF LTC3608IWKG TRPBF LTC3608WKG 52-Lead (7mm 8mm) Plastic QFN 40C to 125C Consult LTC Marketing for parts speciefi d with wider operating temperature ranges. *The temperature grade is identiefi d by a label on the shipping container. For more information on lead free part marking, go to: