a us t ria
m i c r o
s y s t e m s
AS1322
L o w Vo l ta g e , M i c r o p o w e r, D C - D C St e p - U p C o n v e r t e r s
D a ta S he e t
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. Standard Products
Model
AS1322A
AS1322B
Light Load Switching
Automatic Powersave Operation
Continuous Switching
2 Key Features
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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
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.
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.
Figure 1. Typical Application Diagram – Single Cell to 3.3V Synchronous Boost Converter
L1
10µH
1
AA Battery
C
1
10µF
6
SW
5
V
OUT
V
IN
AS1322
4
3
R
1
1.02MΩ
1%
FB
C
2
10µF
V
OUT
3.3V
150mA
On
Off
SHDNN
2 GND
R
2
604kΩ
1%
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