AS1337
Datasheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
The AS1337 can operate from a single-cell input voltage (V
IN
) below 1V, and features fixed frequency (1.2MHz) and
current mode PWM control for exceptional line- and load-regulation. With low R
DS(ON)
and gate charge internal NMOS
and PMOS switches, the device maintains high-efficiency from light to heavy loads.
Modern portable devices frequently spend extended time in low-power or standby modes, switching to high power-
drain only when certain functions are enabled. The AS1337 is ideal for portable devices since they maintain high-
power conversion efficiency over a wide output power range, thus increasing battery life in these types of devices.
In addition to high-efficiency at moderate and heavy loads, the AS1337 includes an automatic powersave mode that
improves efficiency of the power converter at light loads. The powersave mode is initiated if the output load current
falls below a factory programmed threshold.
The Overtemperature protection circuitry turn-off both switches for a short time when the temperature reaches 145ºC
in the device .
Figure 13. AS1337 - Block Diagram
L1
4.7µH
4
1 SW
POK
1.5V
Single
Cell
6
Start Up
OSC
VIN
C
IN
1µF
A
B
A/B
MUX
PWM
Control
Sync Drive
Control
1.2MHz
Ramp
Generator
+
PWM –
Comp
–
Slope
Compensator
Σ
–
V
OUT
Good
+
2.3V
5
3.3V
Output
VOUT
0.35Ω
Current
Sense
0.45Ω
C
FF
*
R
1
1.02MΩ
1%
C
OUT
4.7µF
4
EN
Shutdown
Control
Shutdown
Powersave
Operation
Control
R
C
80kΩ
C
C
150pF
–
g
m
Error
Amp
+
3
FB
C
P2
2.5pF
1.23V
Ref
Powersave
R
2
640kΩ
1%
AS1337
2 GND
* Optional
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