AS1322

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

Dat a Sh eet

www.austriamicrosystems.com

Revision 1.03

1 - 17

1 General Description

The AS1322A and the AS1322B are synchronous, fixed

frequency, very high-efficiency DC-DC boost converters

capable of supplying 3.3V at 150mA from a single AA-

supply. Compact size and minimum external parts

requirements make these devices perfect for modern

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.

The AS1322 is available in a 6-pin TSOT-23 package.

2 Key Features

!

95% Efficiency

!

Single-Cell Operation

!

Delivers 150mA @ 3.3V (from Single AA Cell)

!

Delivers 500mA @ 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 (AS1322A)

!

Continuous Switching at Light Loads (AS1322B)

!

Anti-Ringing Control Minimizes EMI

!

Logic Controlled Shutdown (< 1µA)

!

Output Range: 2.5 to 5.0V

!

6-pin TSOT-23 Package

3 Applications

The AS1322 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

AS1322A

Automatic Powersave Operation

AS1322B

Continuous Switching

AA Battery

AS1322

10µF

604k

Ω

1%

1.02M

Ω

1%

On

Off

L1

10µH

10µF

GND

2

SW

1

3.3V

150mA

4

SHDNN

3

FB

6

5

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