AS1375
Datasheet - Detailed Description
8 Detailed Description
The AS1375 is an low-power and low-quiescent current linear-regulator specifically designed for space-limited applica-
tions. These device can supply loads up to 200mA. As shown in Figure 8, the AS1375 consist of an integrated voltage
reference, error amplifier, P-channel MOSFET pass transistor.
Additional blocks include a current limiter, thermal sensor, and enable logic.
Internal Voltage Reference
The bandgap reference is connected to the error amplifier’s inverting input. The error amplifier 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 low. This allows 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 high, allowing less current to pass to the output.
Figure 8. AS1375 - Block Diagram
IN
Overcurrent
Protection
Voltage
and
Current Reference
-
Enable Con-
trol Logic
EN
+
OUT
GND
Thermal
Protection
AS1375
Current Limit
The AS1375 include a current limiting circuitry to monitor and control the P-channel MOSFET pass transistor’s gate
voltage, thus limiting the device output current to 300mA.
Note: See Table 3 on page 4 for the min and max current limits. The output can be shorted to ground indefinitely
without causing damage to the device.
Thermal Protection
Integrated thermal protection circuitry limits total power dissipation in the AS1375. When the junction temperature (TJ)
exceeds +160ºC, the thermal sensor signals the shutdown logic, turning off the P-channel MOSFET pass transistor
and allowing the device to cool down. The thermal sensor turns the pass transistor on again after the device’s junction
temperature drops by 20ºC, resulting in a pulsed output during continuous thermal-overload conditions.
Note: Thermal protection is designed to protect the devices in the event of fault conditions. For continuous operation,
do not exceed the absolute maximum junction temperature rating of +150ºC.
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