AS1322_13 Datasheet, PDF (1/18 Pages) ams AG – Low Vol tage, Micropower, DC-DC Step-Up Conver ters

AS1322
Low Voltage, Micropower, DC-DC Step-Up Converters
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.
Table 1. Standard Products
Model
Light Load Switching
AS1322A
Automatic Powersave Operation
AS1322B
Continuous Switching
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 to the output and VOUT
is held at approximately VIN - 0.6V.
The AS1322 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
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 (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 equipment, hand-held
instruments, pagers, digital cameras, remote wireless transmitters,
MP3 players, LCD bias supplies, cordless phones, GPS receivers,
and PC cards.
L1
4.7µH
AA Battery
C1
10µF
On
Off
6
VIN
4
SHDNN
1 SW
5
VOUT
AS1322
3
FB
2 GND
R1
1.02MΩ
1%
R2
604kΩ
1%
C2
10µF
VOUT
3.3V
160mA
www.ams.com/DC-DC_Step-Up/AS1322
Revision 1.10
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