LTC3785-1 10V, High Ef ciency, Buck-Boost Controller with Power Good FEATURES DESCRIPTION n Single Inductor Architecture Allows V Above, The LTC 3785-1 is a high power synchronous buck-boost IN Below or Equal to V controller that drives all N-channel power MOSFETs from OUT n Power Good Output Indicator input voltages above, below and equal to the output volt- n 2.7V to 10V Input and Output Range age. With an input range of 2.7V to 10V, the LTC3785-1 is n Up to 96% Ef ciency well suited for a wide variety of single or dual cell Li-Ion n Up to 10A of Output Current or multicell alkaline/NiMH applications. n All N-channel MOSFETs, No R SENSE The operating frequency can be programmed from 100kHz n True Output Disconnect During Shutdown to 1MHz. The soft-start time and current limit are also n Programmable Current Limit and Soft-Start programmable. The soft-start capacitor doubles as the n Optional Short-Circuit Shutdown Timer fault timer which can program the IC to latch off or recycle n Output Overvoltage and Undervoltage Protection after a determined off time. Burst Mode operation is user n Programmable Frequency: 100kHz to 1MHz controlled and can be enabled by driving the mode pin n Selectable Burst Mode Operation high. The LTC3785-1 includes a power good output that n Available in 24-Lead (4mm 4mm) Exposed Pad indicates when the output voltage is within 7.5% of its QFN Package designed setpoint. Protection features include foldback current limit, APPLICATIONS short-circuit and overvoltage protection. n Palmtop Computers L, LT, LTC ,LTM and Burst Mode are registered trademarks of Linear Technology Corporation. n Handheld Instruments No R is a trademark of Linear Technology Corporation. All other trademarks are the SENSE property of their respective owners. n Wireless Modems n Cellular Telephones TYPICAL APPLICATION V IN 2.7V Ef ciency vs Input Voltage V OUT 4.7F TO 10V V IN 100 V CC V = 3.3V OUT F = 500kHz OSC 215k I SVIN 22F TG1 V SENSE 1.3k 215k 127k A 95 I = 2A V LOAD BST1 270pF 0.22F SW1 I = 1A FB LOAD I SSW1 127k 12k V DRV 90 4.7H BG1 1nF LTC3785-1 B V C V OUT RT I 3.3V SVOUT 85 5A 49.9k 2.5 5.5 78.5 10 4 MODE TG2 V (V) IN D 37851 TA01b PGOOD V BST2 0.22F RUN/SS SW2 100F I I LSET SSW2 CCM BG2 42.2k 2.2nF GND C 37851 TA01a 37851fa 1 EFFICIENCY (%)LTC3785-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW Input Supply Voltage (V ) ......................... 0.3V to 11V IN I , I .............................................. 0.3V to 11V SVOUT SVIN 24 23 22 21 20 19 SW1, SW2, I , I Voltage: SSW1 SSW2 RUN/SS 1 18 I SSW1 DC ............................................................. 1V to 11V V 2 17 BG1 C Pulsed, <1s ............................................. 2V to 12V FB 3 16 V DRV 25 RUN/SS, MODE, CCM, V , V Voltages .. 0.3V to 6V DRV CC V 4 15 BG2 SENSE PGOOD Voltage ............................................ 0.3V to 6V I I 5 14 LSET SSW2 V Voltage ............................................. 0.3V to 16V CCM 6 13 SW2 BST1 With Respect to SW1 ............................... 0.3V to 6V 7 8 9 10 11 12 V Voltage ............................................. 0.3V to 16V BST2 With Respect to SW2 ............................... 0.3V to 6V UF PACKAGE Peak Driver Output Current < 10s 24-LEAD (4mm s 4mm) PLASTIC QFN (TG1, TG2, BG1, BG2) .................................................3A T = 125C, = 37C/W 4 LAYER BOARD JMAX JA EXPOSED PAD (PIN 25) IS GND, MUST BE SOLDERED TO PCB V Average Output Current .................................100mA CC Operating Temperature Range (Note 2)....40C to 85C Junction Temperature ........................................... 125C Storage Temperature Range ...................65C to 125C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3785EUF-1 PBF LTC3785EUF-1 TRPBF 37851 24-Lead (4mm 4mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: