AS1322
Low Voltage, Micropower, DC-DC Step-Up Converters
Data Sheet
www.austriamicrosystems.com Revision 1.07 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 pr oducts
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 to the output
and V
OUT is held at approximately VIN - 0.6V.
The AS1322 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
! Automati c 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 application s 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
C2
10µF
R2
604kΩ
1%
R1
1.02MΩ
1%
On
Off
L1
4.7µH
C1
10µF
GND2
SW
1
V
OUT
3.3V
160mA
4
SHDNN
3
FB
6
VIN
5
V
OUT
Figure 1. Typical Application Diagram – Single Cell to 3.3V Synchronous Boost Converter
