AS1325
3 0 0 m A St e p - U p D C - D C C o n v e r t e r
D a ta S he e t
1 General Description
The AS1325 is a high-efficiency step-up DC-DC con-
verter designed to generate a fixed output voltage of
+3.3V or +5V.
The AS1325 achieves an efficiency of up to 96% and the
minimum input voltage is 1.5V. The AS1325-BSTT-33
delivers up to 300mA output current at the fixed output
voltage of +3.3V (@ 2V V
BATT
). With the fixed output
voltage of +5V the AS1325-BSST-50 supplies up to
185mA output current (@ 2V V
BATT
).
In order to save power the AS1325 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.
The AS1325 provides a power-on reset output that goes
high-impedance when the output reaches 90% of its reg-
ulation point.
The SHDNN trip threshold of the AS1325 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.
The AS1325 is available in a 6-pin SOT23 package.
2 Key Features
!
Fixed Output Voltage:
- 3.3V (AS1325-BSTT-33) or 5V (AS1325-BSST-50)
Output Current:
- Up to 300mA (AS1325-BSTT-33) @ 2V V
BATT
- Up to 185mA (AS1325-BSST-50) @ 2V V
BATT
Internal Synchronous Rectifier
Shutdown Mode Supply Current: Less Than 1µA
Efficiency: Up to 96%
Minimum Input Voltage: +1.5V
Accurate Shutdown Low-Battery Cutoff Threshold
Battery Input Connected to Pin OUT in Shutdown
Mode for Backup Power
Antiringing Control Minimizes EMI
Ripple Reduction at Light Loads
6-pin SOT23 Package
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3 Applications
The AS1325 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 supply or as
a battery backup.
Figure 1. Application Diagram
+5.0V Output only
2
BATT
5
OUT
C
OUT
22µF
+3.3 or
+5.0V
Output
R
1
100kΩ
RESETN
Output
+1.5 to +3.3V or
+1.5 to +5.0V
Battery
C
IN
22µF
4
L1
10µH
LX
AS1325
6
RESETN
On
Off
1
SHDNN
3
GND
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