AS1329

Low Vo ltage, Micropower, DC-DC Step-Up Converters

Produ ct Brief

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Revision 1.01

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1 General Description

The AS1329A, AS1329B and the AS1329C are synchro-

nous, fixed frequency, very high-efficiency DC-DC boost

converters capable of supplying 3.3V at 160mA from a

single AA-supply. Compact size and minimum external

parts requirements make these devices perfect for mod-

ern portable devices.

High-speed switching frequency (1.2MHz) and internally

compensated PWM current mode design provide highly-

reliable DC-DC conversion, especially when driving

white LEDs.

The converters are available as the standard products

listed in Table 1.

The devices contain two internal MOSFET switches:

one NMOS switch and one PMOS synchronous rectifier.

Anti-ringing control circuitry reduces EMI by damping

the inductor in discontinuous mode, and the devices

exhibit extremely low quiescent current (< 1µA) in shut-

down.

In shutdown mode the battery is connected directly to

the output enabling the supply of real-time-clocks.

The AS1329 is available in a 6-pin TSOT-23 package.

2 Key Features

!

95% Efficiency

!

Single-Cell Operation

!

Delivers 160mA @ 3.3V (from Single AA Cell)

!

Delivers 220mA @ 5.0V (from Two AA Cells)

!

Delivers 570mA @ 3.3V (from Two AA Cells)

!

Low Start-Up Voltage: 0.85V

!

High-Speed Fixed-Frequency: 1.2MHz

!

Internal PMOS Synchronous Rectifier

!

Automatic Powersave Operation (AS1329A&B)

!

Continuous Switching at Light Loads (AS1329C)

!

Anti-Ringing Control Minimizes EMI

!

Logic Controlled Shutdown (< 1µA)

!

Output Range: 2.5 to 5.0V

!

6-pin TSOT-23 Package

3 Applications

The AS1329 is ideal for low-power applications where

ultra-small size is critical as in medical diagnostic equip-

ment, hand-held instruments, pagers, digital cameras,

remote wireless transmitters, MP3 players, LCD bias

supplies, cordless phones, GPS receivers, and PC

cards.

Table 1. Standard Products

Model

Light Load Switching

AS1329A

Medium Load

Automatic Powersave Operation

AS1329B Light Load Automatic Powersave Operation

AS1329C

Continuous Switching

AA Battery

AS1329

10µF

604k

Ω

1%

1.02M

Ω

1%

On

Off

L1

4.7µH

10µF

GND

2

SW

1

3.3V

160mA

4

SHDNN

3

FB

6

5

Figure 1. Typical Application Diagram – Single Cell to 3.3V Synchronous Boost Converter