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| 19-0987; Rev 0; 10/07 ABRIDGED Smallest, All-Internal MOSFET, 7-Channel 2 AA DSC PMIC General Description Features 95% Efficient Synchronous-Rectified DC-DC Converters 90% Efficient Boost-Buck Operation Up to 85% Efficient, High-Voltage DC-DC Converters Inverter Operates Directly from 2 AA Batteries Internal Compensation on All Channels True ShutdownTM on All Step-Up Converters Overload Protection Startup into Short Protection Soft-Start for Controlled Startup Current Regulated Current Output for Up to 6 White LEDs PWM Dimming of WLED Current Adjustable LED Overvoltage Protection Up to 27V Transformerless Inverting Converter for CCD KIT ATION EVALU ILABLE AVA MAX8857A The MAX8857A PMIC provides a complete power-supply solution for digital still cameras (DSCs) and digital video cameras (DVCs). The MAX8857A improves performance, component count, and board space utilization compared to currently available solutions for 2 AA cell and dual-battery designs. On-chip power MOSFETs provide up to 95% efficiency for critical power supplies. The CCD inverter can operate directly from 2 AA/NiMH batteries without the use of any additional external components. * Step-up synchronous-rectified DC-DC converter (SU). The MAX8857A is bootstrapped from VSU. * * * MAIN synchronous-rectified step-up DC-DC converter (M) with active discharge for DSP I/O supply voltage. SDZ synchronous-rectified step-down DC-DC converter (Z) for DSP DDR supply voltage. Low-voltage (down to 1V) synchronous-rectified step-down DC-DC converter (SD) for DSP core supply voltage. Step-up DC-DC converter with current regulation and PWM dimming control (LEDBST) for up to 6 series white LEDs (WLED). High-voltage step-up DC-DC converter (CCDBST) for CCD imagers or positive LCD bias supplies. Transformerless inverting DC-DC converter (CCDINV) for CCD imagers or negative LCD bias supplies. This converter can connect directly to 2 AA batteries. 100% Duty Cycle on Step-Down Converters * 2MHz 2.5% Switching Frequency 1A Shutdown Supply Current CCD Voltage Sequencing All Internal Power MOSFETs SDOK Power-OK Indicator * * Typical Operating Circuit INPUT 1.8V TO 5.5V PVBST ONSU ONM ONSD ONZ SDOK ONLED ONBST ONINV LEDBST CCDBST CCDINV VLEDBST UP TO 6 WLEDs VCCDBST +15V VCCDINV -7.5V SU STEP-UP MAIN STEP-UP SD STEP-DOWN SDZ STEP-DOWN VSU 5V VMAIN 3.3V VSD 1.8V VDDRZ 2.5V The MAX8857A has an independent/simultaneous power-on sequence of the CCDBST and CCDINV converters. For a preset power-on sequence of CCDBST before CCDINV, contact the factory. The MAX8857A is available in a 5mm x 5mm, 40-pin thin QFN package and operates over the -40C to +85C extended temperature range. Applications DSCs and DVCs PDAs and Portable Media Players MAX8857A Ordering Information PART MAX8857AETL+ TEMP RANGE -40C to +85C PIN-PACKAGE 40 Thin QFN-EP* 5mm x 5mm x 0.8mm PKG CODE T4055-2 +Denotes a lead-free package. *EP = Exposed paddle. Note: Contact factory for the option where CCDBST must reach regulation before the INV converter can be turned on. Pin Configuration appears at the end of data sheet. True Shutdown is a trademark of Maxim Integrated Products, Inc. 1 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. ABRIDGED Smallest, All-Internal MOSFET, 7-Channel 2 AA DSC PMIC MAX8857A VREF VBATT C20 0.1F VBATT (1.8V TO 5.5V) C1 22F C2 22F 24 REF 16 PVINV 15 LXINV C18 1F D3 VCCDINV (-7.5V, 100mA) L1 2H 32 31 LXSU LXSU PVSU FBINV SWBST 23 17 L7 10H C19 10F R13 604k VSU (5V, 500mA) C3 22F R1 402k C4 22F R17 100 29 30 PVSU R14 100k L6 2.2H MAX8857A 26 SU LXBST PGBST (EP) 27 FBSU PGSU (EP) FBBST 22 20 D2 C17 2.2F VREF VCCDBST (15V, 30mA) R11 1.4M C21 0.1F R2 100k C5 1F VBATT PVBST 18 VBATT PVLED SWLED 13 14 11 10 VSU 19 9 L5 4.7H D1 VBATT 39, 40 L2 1H LXM C16 1F R12 100k VMAIN (3.3V, 300mA) R3 23.2k C6 22F C7 22F C14 1F VLEDBST (16V, 25mA) C15 3.3F R9 1.6M D7 D6 1, 2 PVM 3 R4 10k C8 10F VBATT 34 FBM PGM (EP) LXLED OVLED C23 1F, OPTIONAL PVSD PVGD FBLED R10 100k D5 D4 VSD (1.8V, 250mA) R5 80.6k C10 10F C9 10F L3 4.7H 35 LXSD PGLED (EP) EP GND PVZ 25 36 L4 4.7H C12 10F FBZ PGZ (EP) SDOK 5 R16 100k VBATT R8 100k C13 10F VDDRZ (2.5V, 200mA) R7 150k VSU C11 1F R15 10 7 R6 100k VBATT VSU NOTE 1: ALL ON_ PINS HAVE INTERNAL 1M PULLDOWN TO GROUND. NOTE 2: ALL CONVERTERS' POWER GROUND CONNECTIONS ARE THROUGH THE EXPOSED PADDLE (EP). 28 4 33 12 21 8 38 FBSD PGSD (EP) ONSU ONM ONSD ONLED ONBST ONINV ONZ LXZ 37 6 Figure 1. MAX8857A Typical Application Circuit 14 ______________________________________________________________________________________ |
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