Datasheet
AS1321
130mA Step-Up DC-DC Converter
1 General Description
2 Key Features
The AS1321 is a high-efficiency step-up DC-DC con-
verter designed to generate a fixed output voltage of
+5.0V.
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Fixed Output Voltage: +5.0V
Output Current: Up to 130mA (@ 2V VBATT)
Internal Synchronous Rectifier
The AS1321 achieves an efficiency of up to 96%. The
minimum input voltage is +1.5V, the output voltage is
fixed at +5.0V, and output current is up to 130mA
(@ 2V VBATT).
Shutdown Mode Supply Current: Less Than 1µA
Efficiency: Up to 96%
In order to save power the AS1321 features a shutdown
mode, where it draws less than 1µA. In shutdown mode
the battery is connected directly to the output enabling
the supply of real-time-clocks.
Minimum Input Voltage: +1.5V
Accurate Shutdown Low-Battery Cutoff Threshold
The AS1321 provides a power-on reset output that goes
high-impedance when the output reaches 90% of its reg-
ulation point.
Battery Input Connected to Pin OUT in Shutdown
Mode for Backup Power
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6-pin SOT23 Package
The SHDNN trip threshold of the AS1321 can be used
as an input voltage detector that disables the device
when the battery voltage falls to a predetermined level.
An internal synchronous rectifier is included, which is
parallel with the external Schottky diode.
3 Applications
The AS1321 is available in a 6-pin SOT23 package.
The AS1321 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, cordless phones, and PC
cards.
The device is also perfect as a local +5.0V supply or as
a battery backup.
Figure 1. AS1321 - Typical Application Diagram
+5.0V
2
5
Output
BATT
OUT
COUT
22µF
R1
100kΩ
4
6
+1.5V to +5.0V
Battery
RESETN
Output
AS1321
L1
10µH
LX
RESETN
CIN
22µF
1
3
On
Off
SHDNN
GND
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Revision 1.02
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