MAX8857A:Smallest, All-Internal MOSFET, 7-Channel 2 AA DSC PMIC

Highly Efficient 2 AA DSC PMIC

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. 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 -40°C to +85°C extended temperature range.

Key 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 Shutdown™ on All Step-Up Converters
  • Overload Protection
  • Startup into Short Protection
  • Soft-Start for Controlled Startup Current
  • 100% Duty Cycle on Step-Down Converters
  • 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
  • 2MHz ±2.5% Switching Frequency
  • 1µA Shutdown Supply Current
  • CCD Voltage Sequencing
  • All Internal Power MOSFETs
  • SDOK Power-OK Indicator
MAX8857A: Typical Operating Circuit
MAX8857A: Typical Operating Circuit
Applications/Uses
  • DSCs and DVCs
  • PDAs and Portable Media Players
DataSheet
titleDownload file
MAX8857A Data SheetMAX8857A.pdf
Parametrics
Part NumberPrimary TopologyMonitor/Control FeaturesDC-DC/Power FeaturesLCD/LED/Flash/CCD FeaturesInterface TypeVIN
(V)
VIN
(V)
VOUT
(V)
VOUT
(V)
Max. IOUT
(A)
Oper. Freq.
(kHz)
Inverting OutputsPackage/Pins
minmaxminmax
MAX8857AStep-UpLow Batt./POK Output
Output OVP
Current Limit
Fixed Freq./PWM
Internal Switch
Soft Start
Sync. Rectifier
CCD Bias
TFT Bias
White LED
GPIO0.95.5127120001TQFN/40
Design kits & evaluation modules
Quality and Environmental Data
Related Products
  • MAX8680:Smallest, All-Internal MOSFET, 7-Channel DSC PMIC in Tiny 5mm x 5mm Thin QFN
  • MAX858:3.3V/5V or Adjustable Output, Step-Up DC-DC Converters
Ordering Information
Part NumberStatusRecommended ReplacementPackageTempRoHS
MAX8857AETL+ActiveTQFN,;40 pin;26 mm²-40°C to +85°CLead Free
MAX8857AETL+TActiveTQFN,;40 pin;26 mm²-40°C to +85°CLead Free
MAX8857A.pdf MAX8857A
MAX8857A.pdf MAX8857A
MAX8857A.pdf MAX8857A
MAX8857A.pdf MAX8857A
典型工作电路 MAX8857A