AS1322_1 Datasheet, PDF (1/17 Pages) ams AG – Low Voltage, Micropower, DC-DC Step-Up Converters

AS1322
Data Sheet
Low Voltage, Micropower, DC-DC Step-Up Converters
1 General Description
2 Key Features
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
! 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
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.
! Logic Controlled Shutdown (< 1µA)
! Output Range: 2.5 to 5.0V
! 6-pin TSOT-23 Package
3 Applications
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.
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
4.7µH
AA Battery
C1
10µF
1 SW
6
5
VIN
VOUT
AS1322
On
4
3
Off
SHDNN
FB
2 GND
R1
1.02MΩ
1%
R2
604kΩ
1%
C2
10µF
VOUT
3.3V
160mA
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Revision 1.07
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