LTC3878 Fast, Wide Operating Range No R Step-Down SENSE DC/DC Controller Fae Tseru Dpircse Tnoi n The LTC 3878 is a synchronous step-down switching Wide V Range: 4Vto 38V IN n DC/DC controller optimized for high switching frequency 1%0.8V V oltageReference n and fast transient response. The constant on-time valley Extremely Fast Transient Response n current mode architecture allows for a wide input range, t : 43ns ON(MIN) n including very low duty factor operation. No external sense NoR ValleyCurrent Mode Control SENSE n resistor or slope compensation is required. The LTC3878 Stablewith Low ESRCeramic C OUT n is pin compatible with the LTC1778 in applications that do SupportsSmooth Start-UpInto Pre-Biased Output n not use EXTV while offering better efficiency. Consult Optimizedfor High Step-Down Ratios CC n withthe factor y to verifycompatibility . PinCompatible with the LTC1778 (NoEXT V Pin) CC n PowerGood Output Voltage Monitor Operating frequency is set by an external resistor and n DualN-Channel MOSFET Synchronous Drive compensated for variations in V to offer excellent line IN n AdjustableSwitching Frequency stability. Discontinuous mode operation provides high n Programmable Current Limitwith Foldback efficiency during light load conditions. A forced continu- n Output Overvoltage Protection ous control pin allows the user to reduce noise and RF n Small16-Pin Narrow SSOP Package interference. Safety features include output overvoltage protection and programmable current limit with foldback. a acilpp Tsnoi Soft-start capability for supply sequencing is accomplished n through an external timing capacitor. The current limit is Distributed Power Systems n userprogrammable. Embedded Computing n CommunicationsInfrastructure The LTC3878 allows operation from 4V to 38V at the input L,L T,L TC,L TM, LinearT echnology and the Linear logo are registered trademarks of Linear and from 0.8V to 90% V at the output. The LTC3878 is IN Technology Corporation. NoR is atrademark of Linear Technology Corporation. SENSE All othertrademarks arethe property of their respective owners. availablein a small 16-pin narrow SSOP package. Protected byU.S. Patents, including 5481178, 6100678,6580258, 5847554, 6304066. T lacipy a acilpp Tnoi Efficiencyvs Load Current HighEfficiency Step-Down Converter 100 432k DISCONTINUOUS 0.1F 90 I ON MODE V IN RUN/SS V 80 IN 4.5V TO 28V 220pF TG RJK0305 70 10F 12.1k LTC3878 CONTINUOUS I SW 60 TH 0.56H V OUT MODE SGND BOOST 1.2V 50 15A FCB 0.22F 40 INTV 330F CC s2 30 RJK0330 BG 4.7F V = 12V IN 20 V = 1.2V PGOOD PGND OUT SW FREQ = 400kHz 10 V 5.11k RNG FIGURE 7 CIRCUIT 0 V FB 0.01 0.1 1 10 100 10k LOAD CURRENT (A) 3878 G07 3878 TA01a 3878fa EFFICIENCY (%)LTC3878 a ulosb T e Mixa Mu M r a Tsgni p ni c no Farugi Tnoi (Note1) TOP VIEW InputSupply V oltage (V ) ......................... 0.3V to 40V IN I V oltage ................................................. 0.3V to 40V RUN/SS 1 16 BOOST ON PGOOD 2 15 TG BOOST Voltage .......................................... 0.3V to 46V V 3 14 SW RNG SWV oltage ................................................... 5Vto 40V FCB 4 13 PGND INTV , (BOOST-SW), RUN/SS, CC I 5 12 BG TH PGOODV oltages .......................................... 0.3Vto 6V SGND 6 11 INTV CC FCB,V V oltages .................... 0.3V to INTV +0.3V RNG CC I 7 10 V ON IN V ,I Voltages ....................................... 0.3V to 2.7V FB TH V 8 9 NC FB OperatingT emperature Range(Note 4) .... 40C to 85C GN PACKAGE JunctionT emperature(Note 2) ............................. 125C 16-LEAD PLASTIC SSOP NARROW Storage Temperature Range ................... 65C to 150C T = 125C, = 110C/W JMAX JA Lead Temperature (Soldering,10 sec) .................. 300C ro D re ni Fro Ma Tnoi LEADFREE FINISH TAPEAND REEL PARTMARKING* PACKAGEDESCRIP TION TEMPERATURE RANGE LTC3878EGN PBF LTC3878EGN TRPBF 3878 16-Lead Plastic SSOP 40Cto 85C (Note4) LTC3878IGN PBF LTC3878IGN TRPBF 3878 16-Lead PlasticSSOP 40C to 85C (Note4) 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. Consult LTCMarketing for information on non-standard leadbased finishparts. Formore information on lead free part marking, go to: