MAX8857A MAXIM [Maxim Integrated Products], MAX8857A Datasheet

MAX8857A

Manufacturer Part Number

MAX8857A

Description

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

Manufacturer

MAXIM [Maxim Integrated Products]

Datasheet

1.MAX8857A.pdf (2 pages)

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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.

•

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.

19-0987; Rev 0; 10/07

+ 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.

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.

MAX8857AETL+

Step-up synchronous-rectified DC-DC converter

(SU). The MAX8857A is bootstrapped from V

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.

PART

DSCs and DVCs

PDAs and Portable Media Players

-40°C to

RANGE

________________________________________________________________ Maxim Integrated Products

TEMP

+85°C

Ordering Information

General Description

PIN-PACKAGE

40 Thin QFN-EP*

5mm x 5mm x 0.8mm

Applications

Smallest, All-Internal MOSFET,

T4055-2

CODE

PKG

7-Channel 2 AA DSC PMIC

♦ 95% Efficient Synchronous-Rectified DC-DC

♦ 90% Efficient Boost-Buck Operation

♦ Up to 85% Efficient, High-Voltage DC-DC

♦ 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

Pin Configuration appears at the end of data sheet.

True Shutdown is a trademark of Maxim Integrated Products, Inc.

1.8V TO 5.5V

Converters

INPUT

PVBST

ONSU

ONM

ONSD

ONZ

ONLED

ONBST

ONINV

SDOK

Typical Operating Circuit

MAX8857A

SDZ STEP-DOWN

SD STEP-DOWN

MAIN STEP-UP

SU STEP-UP

CCDBST

CCDINV

LEDBST

MAIN

DDRZ

LEDBST

CCDBST

CCDINV

1.8V

Features

3.3V

2.5V

UP TO 6 WLEDs

-7.5V

+15V

Related parts for MAX8857A

MAX8857A Summary of contents

Page 1

... 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. DSCs and DVCs ...

Page 2

... R6 100kΩ V NOTE 1: ALL ON_ PINS HAVE INTERNAL 1MΩ PULLDOWN TO GROUND. NOTE 2: ALL CONVERTERS’ POWER GROUND CONNECTIONS ARE THROUGH THE EXPOSED PADDLE (EP). Figure 1. MAX8857A Typical Application Circuit 14 ______________________________________________________________________________________ V REF C20 0.1μ REF PVINV LXINV C2 22μF L1 2μ ...

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