AS1337
200mA, DC-DC Step-Up Converter with Buck Mode
www.austriamicrosystems.com Revision 1.03 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.
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 Fi xed-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.
VIN = 2xAA
1.6V to 3.6V
Figure 1. AS1337 - Typical Application Diagram – Dual Cell to 3.3V Synchronous Boost Converte r
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