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Rainbow Electronics MAX8625A User Manual

General description, Applications, Features

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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.

General Description

The MAX8625A PWM step-up/down regulator is intend-
ed to power digital logic, hard disk drives, motors, and
other loads in portable, battery-powered devices such
as PDAs, cell phones, digital still cameras (DSCs), and
MP3 players. The MAX8625A provides either a fixed
3.3V or adjustable output voltage (1.25V to 4V) at up to
0.8A from a 2.5V to 5.5V input. The MAX8625A utilizes
a 2A peak current limit.

Maxim’s proprietary H-bridge topology* provides a
seamless transition through all operating modes without
the glitches commonly seen with other devices. Four
internal MOSFETs (two switches and two synchronous
rectifiers) with internal compensation minimize external
components. A SKIP input selects a low-noise, fixed-
frequency PWM mode, or a high-efficiency skip mode
where the converter automatically switches to PFM
mode under light loads for best light-load efficiency.
The internal oscillator operates at 1MHz to allow for a
small external inductor and capacitors.

The MAX8625A features current-limit circuitry that shuts
down the IC in the event of an output overload. In addi-
tion, soft-start circuitry reduces inrush current during
startup. The IC also features True Shutdown

TM

, which

disconnects the output from the input when the IC is
disabled. The MAX8625A is available in a 3mm x 3mm,
14-pin TDFN package.

Applications

PDAs and Smartphones

DSCs and Camcorders

MP3 Players and Cellular Phones

Battery-Powered Hard Disk Drive (HDD)

Features

Four Internal MOSFET True H-Bridge Buck/Boost
Glitch-Free, Buck-Boost Transitions
Minimal Output Ripple Variation on Transitions
Up to 92% Efficiency
37µA (typ) Quiescent Current in Skip Mode
2.5V to 5.5V Input Range
Fixed 3.3V or Adjustable Output
1µA (max) Logic-Controlled Shutdown
True Shutdown
Output Overload Protection
Internal Compensation
Internal Soft-Start
1MHz Switching Frequency
Thermal-Overload Protection
Small 3mm x 3mm, 14-Pin TDFN Package

MAX8625A

High-Efficiency, Seamless Transition,

Step-Up/Down DC-DC Converter

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

MAX8625A

SKIP

IN

GND

FB

OUT

LX1

LX2

ON

INPUT

2.7V TO 5.5V

OUTPUT

3.3V

OFF

ON

PWM

SKIP

REF

Typical Operating Circuit

19-1006; Rev 1; 5/08

*

US Patent #7,289,119.

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

EVALUATION KIT

AVAILABLE

Note: The device is specified over the -40°C to +85°C extended
temperature range.
+

Denotes a lead-free package.

**

EP = Exposed pad.

PART

PIN-
PACKAGE

TOP MARK

MAX8625AETD+

14 TDFN-EP**
(3mm x 3mm)

ABQ

MAX8625A

TDFN-EP

TOP VIEW

2

4

5

13

11

10

IN

GND

OUT

LX1

LX2

ON

1

+

14

IN

LX1

3

12

GND

LX2

6

9

OUT

SKIP

7

8

REF

FB

EP

EP = EXPOSED PAD.

Pin Configuration