Datas heet
AS1337
2 0 0 m A , D C - D C St e p - U p C o n v e r t e r w i t h B u c k M o d e
1 General Description
The AS1337 is a synchronous, fixed frequency,
highefficiency 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
powersave mode 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 AS1337B the battery
is disconnected and the output is discharged.
Table 1. Standard Products
Model
AS1337A
AS1337B
Operation Mode
Battery Connected in Shutdown
Battery Disconnected in Shutdown
and Output Discharged
2 Key Features
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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 Control 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 instruments, pagers,
digital cameras, remote wireless transmitters, MP3
players, LCD bias supplies, cordless phones, GPS
receivers, and PC cards.
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
.
Figure 1. AS1337 - Typical Application Diagram – Dual Cell to 3.3V Synchronous Boost Converter
3.6V
Buck Mode
V
OUT
=3.3V
2x AA Cell Range
V
IN
Curve
Boost Mode
L1
4.7µH
V
IN
= 2xAA
1.6V to 3.6V
C
IN
10µF
On
Off
V
OUT
= 3.3V
LX
VIN
VOUT
FB
C
OUT
22µF
AS1337
EN
GND
POK
PGND
1.6V
Revision 1.04
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