AS1363
Datasheet - Detailed Description
8 Detailed Description
The AS1363 is a low-dropout, low-quiescent-current linear regulator specifically designed for battery-powered devices.
The regulator supplies loads of up to 500mA and can deliver a factory-preset output voltage or user-adjustable output
voltage.
The device features a 1.2V reference, error amplifier, P-channel pass transistor, and internal feedback voltage-divider
(see Figure 15). Additional blocks include an output current limiter, thermal sensor, and shutdown logic.
Figure 15. Block Diagram
VIN
2.0V to 5.5V
1
IN
CIN
Thermal
Sensor
1µF
MOSFET
Driver
w/ILIM
VOUT
1.2V to 5.3V
6
3
Shutdown
Logic
OUT
On
Off
COUT
2.2µF
EN
5kΩ
1.25V
Reference
+
–
Error
Amplifier
R1
VOUT Logic
Supply Voltage
RPOK
100kΩ
2
5
To Controller
POK
SET
+
–
+
–
R2
+
–
+
–
93%VREF
100mV
4
GND
AS1363-AD
The 1.2V reference is connected to the error amplifier, which compares this reference with the feedback voltage and
amplifies the difference. If the feedback voltage is lower than the reference voltage, the pass-transistor gate is pulled
lower, allowing more current to pass to the output and increases the output voltage. If the feedback voltage is too high,
the pass transistor gate is pulled up, allowing less current to pass to the output.
The output voltage is delivered back through either an internal resistive divider connected to OUT or an external resis-
tor network connected to SET (see Figure 15). The comparator examines VSET/BYP and selects the feedback path. If
VSET/BYP is less than 50mV, the internal feedback path is used and the output is regulated to the factory-preset voltage
(see Ordering Information on page 13).
Internal P-Channel Pass Transistor
The AS1363 features a P-channel MOSFET pass transistor and consumes only a maximum of 200µA of quiescent
current under heavy loads as well as in dropout.
Shutdown
If pin EN is connected to GND the AS1363 is disabled. In shutdown mode all internal circuits are turned off, reducing
supply current to 30nA (typ.). For normal operation pin EN must be connected to IN. During shutdown, POK is low.
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