MAX8857A Datasheet, PDF (1/2 Pages) Maxim Integrated Products – Smallest, All-Internal MOSFET, 7-Channel 2 AA DSC PMIC

19-0987; Rev 0; 10/07
EVAALVUAAILTAIOBNLEKIT
ABRIDGED
Smallest, All-Internal MOSFET,
7-Channel 2 AA DSC PMIC
General Description
The MAX8857A PMIC provides a complete power-sup-
ply solution for digital still cameras (DSCs) and digital
video cameras (DVCs). The MAX8857A improves per-
formance, component count, and board space utiliza-
tion 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 addi-
tional external components.
• Step-up synchronous-rectified DC-DC converter
(SU). The MAX8857A is bootstrapped from V_SU.
• 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 con-
verter (Z) for DSP DDR supply voltage.
• Low-voltage (down to 1V) synchronous-rectified
step-down DC-DC converter (SD) for DSP core sup-
ply 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 con-
verters. 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.
Applications
DSCs and DVCs
PDAs and Portable Media Players
Ordering Information
PART
TEMP _PIN-PACKAGE
RANGE
PKG
CODE
MAX8857AETL+ ^{-40°C to 40 Thin QFN-EP*}
T4055-2
+85°C 5mm x 5mm x 0.8mm
+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.
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
Typical Operating Circuit
INPUT
1.8V TO 5.5V
PVBST
ONSU
ONM
SU STEP-UP
MAIN STEP-UP
SD STEP-DOWN
ONSD
SDZ STEP-DOWN
ONZ
MAX8857A
SDOK
ONLED
LEDBST
ONBST
CCDBST
ONINV
CCDINV
V_SU 5V
V_MAIN 3.3V
V_SD 1.8V
V_DDRZ 2.5V
V_LEDBST UP TO 6 WLEDs
V_CCDBST +15V
V_CCDINV -7.5V
Pin Configuration appears at the end of data sheet.
True Shutdown is a trademark of Maxim Integrated Products, Inc.
________________________________________________________________ Maxim Integrated Products 1
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.