A S1 3 1 2
Ul tr a L o w Q u ie s c e n t Cu rr e n t , H y s te r e ti c D C- DC St ep - U p C o n v e r te r
1 General Description
The AS1312 is an ultra low I
Q
hysteretic step-up DC-DC converter.
The AS1312 achieves an efficiency of up to 94% and is designed to
operate from a +0.7V to +5.0V supply, the output voltage is fixed in
50mV steps from +2.5V to 5.0V.
In order to save power the AS1312 features a shutdown mode,
where it draws less than 100nA. In shutdown mode the battery is not
connected to the output.
If the input voltage exceeds the output voltage the device is in a
feedthrough mode and the input is directly connected to the output
voltage.
In light load operation, the device enters a sleep mode when most of
the internal operating blocks are turned off in order to save power.
This mode is active approximately 50µs after a current pulse
provided that the output is in regulation.
The AS1312 also offers an adjustable low battery detection. If the
battery voltage decreases below a threshold defined by two external
resistors on pin LBI, the LBO output is pulled to logic low. LBO is
working as Power-OK when LBI is connected to GND.
The AS1312 is available in a 8-pin (2x2) TDFN and a 0.4mm pitch 8-
pin WL-CSP package.
2 Key Features
Input voltage range: 0.7V to 5.0V
Fixed output voltage range: 2.5V to 5.0V
Peak output current: 200mA
Quiescent current: 1µA
Shutdown current: < 100nA
Up to 94% efficiency
Output disconnect in shutdown
Feedthrough mode when V
IN
> V
OUT
Adjustable low battery detection or Power-OK output selectable
No external diode or transistor required
Over temperature protection
Packages:
- 8-pin (2x2) TDFN
- 8-pin WL-CSP with 0.4mm pitch
3 Applications
The AS1312 is an ideal solution for handheld devices and battery
powered products.
Figure 1. AS1312 - Typical Application Diagram
L1 = 6.8µH
LX
Low Battery Detect
VIN
C
1
= 22µF
R
1
LBI
On
Off
LBO
R
3
V
OUT
2.5V to 5.0V
C
2
= 10µF
REF
C
REF
= 100nF
GND
V
IN
0.7V to 5.0V
AS1312
R
2
VOUT
EN
www.ams.com/DC-DC_Step-Up
Revision 1.12
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AMSCO [ AUSTRIAMICROSYSTEMS AG ]
