AS1337
200mA, DC-DC Step-Up Converter with Buck Mode
www.austriamicrosystems.com/DC-DC_Step-Up/AS1337 Revision 1.04 1 - 14
Datasheet
1 General Description
The AS1337 is a synchronous, fixed frequency,
highef ficiency DC-DC boost converter capable of
supplying
3.3V @ 200mA from two AA Cells. Com -
pact size and minimum external parts require-
ments make these devices perfect for modern
portable devices. The AS1337 offers automatic
powersav e mo d e to
increase efficiency at light
loads. For input voltages higher than VOUT the
AS1337 will switch in a step down mode, so that a
Buck Boost function is realized.
The AS1337A offers a shutdown mode where the
battery is connected directly to the output enabling
the supply of real-time-clocks or memories.
In the shutdown mode of the AS1337 B the battery
is disconnected and the ou tput is discharged.
The AS1337 offers a POK (open-drain) feature
which detects output power fail of 10%.
The AS1337 is available in a
TDFN (3x3mm) 8-pin
package
.
2 Key Features
! Input Voltage Range: 0.65V to 4.5V
! Low Start-Up Voltage: 0.85V
! Output Voltage Range: 2.5V to 5.0V
! Delivers 200mA @ 3.3V (from two AA Cell)
! up to 97% Efficiency
! High-Speed Fixed-Frequency: 1.2MHz
! Single-Cell Operation
! Internal PMOS Synchronous Rectifier
! Automatic Powersave Operation
! Anti-Ringing Con trol Minimizes EMI
! Logic Controlled Shutdown (< 1µA)
! TDFN (3x3mm) 8-pin Package
3 Applications
The AS1337 is ideal for low-power applications
where
ultra-small size is critical as in medical diag-
nostic equipment, hand-held in struments, pagers,
digital cameras,
remote wireless transmitters, MP3
players, LCD bias supplies, cordless phones, GPS
receivers, and PC
cards.
Table 1. Standard Products
Model Operation Mode
AS1337A Battery Connected in Shutdown
AS1337B
Battery Disconnected in Shutdown
and Output Discharged
VIN = 2xAA
1.6V to 3.6V
Figure 1. AS1337 - Typical Application Diagram – Dual Cell to 3.3V Synchronous Boost Converter
2x AA Cell Range
3.6V
1.6V
V
OUT
=3.3V
Buck Mode
Boost Mode
AS1337
C
OUT
22µF
L1
4.7µH
VOUT = 3.3V
GND
FB
VIN
EN
PGND
POK
V
IN
Curve
LX
VOUT
On
Off
C
IN
10µF
