www.ams.com/DC-DC_Step-Up/AS1329

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A S 1 3 2 9

L o w Vo l t a g e , M i c r o p o w e r, D C - D C S t e p - U p C o n v e r t e r s

1 General Description

The AS1329A, AS1329B and the AS1329C are synchronous, 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

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 shutdown.

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.

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

Synchronous Boost Converter

2 Key Features

Low Start-Up Voltage: 0.85V

Output Range: 2.5V to 5.0V

Single-Cell Operation

Operating with coils down to 2.2µH

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

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

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

95% Efficiency

High-Speed Fixed-Frequency: 1.2MHz

Internal PMOS Synchronous Rectifier

Automatic Powersave Operation (AS1329A&B)

Continuous Switching at Light Loads (AS1329C)

Logic Controlled Shutdown (< 1µA)

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 equipment, 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

VIN

5

VOUT