AS1330
Datasheet - Detailed Description
8 Detailed Description
The AS1330 can operate from a single-cell input voltage (VIN) below 1V, and features fixed frequency (4MHz) and cur-
rent mode PWM control for exceptional line- and load-regulation. With low RDS(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 AS1330 is ideal for portable devices since it 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 AS1330 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.
Figure 19. AS1330 - Block Diagram
L1
1µH
1
SW
AA Battery
6
Start Up
OSC
1.65V
–
+
VOUT
Good
1.8V
Output
VIN
A
B
A/B
MUX
5
C1
4.7µF
VOUT
PWM
Control
0.35Ω
0.25Ω
Sync Drive
Control
Current
Sense
4MHz
Ramp
Generator
Σ
Slope
Compensator
AS1330
+
3
PWM
Comp
–
–
–
FB
gm Error
Amp
+
4
On
Off
C2
4.7µF
Shutdown
Control
RC
CC
Shutdown
EN
CP2
0.8V
Ref
Powersave
Operation
Control
Powersave
4
1
Sense & POK
Logic
POK
SENSE
2
GND
Low-Voltage Start-Up
The AS1330 requires VIN of only 0.85V (typ) or higher to start up. The low-voltage start-up circuitry controls the internal
NMOS switch up to a maximum peak inductor current of 650mA (typ), with 1.5ms (approx.) off-time during start-up,
allowing the devices to start up into an output load.
With a VOUT > 1.65V, the start-up circuitry is disabled and normal fixed-frequency PWM operation is initiated. In this
mode, the AS1330 operates independent of VIN, allowing extended operating time as the battery can drop to several
tenths of a volt without affecting output regulation. The limiting factor for the application is the ability of the battery to
supply sufficient energy to the output.
www.austriamicrosystems.com/DC-DC_Step-Up/AS1330
Revision 1.04
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AMSCO [ AMS(艾迈斯) ]
