AS1371
Datasheet - Detailed Description
8 Detailed Description
The AS1371 is a low-dropout, low-quiescent-current linear regulator intended for LDO regulator applications where
output current load requirements range from no load to 400mA. All devices come with fixed output voltage from 0.6V to
3.3V. (see Ordering Information on page 13).
The AS1371 also features a Power-OK output to indicate when the output is within 10% (max) of final value, and also
an Enable pin. Shutdown current for the whole regulator is typically 10nA. The device features integrated short-circuit
and over current protection. Under-Voltage lockout prevents erratic operation when the input voltage is slowly decaying
(e.g. in a battery powered application). Thermal Protection shuts down the device when die temperature reaches
150°C. This is a useful protection when the device is under sustained short circuit conditions.
As illustrated in Figure 13, the devices comprise voltage reference, error amplifier, P-channel MOSFET pass transistor,
Power-OK detect logic, internal voltage divider, current limiter, thermal sensor and shutdown logic.
The bandgap reference is connected to the inverting input of the error amplifier. 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 P-channel MOSFET 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 feeds back through an internal resistor voltage divider connected to pin OUT.
Figure 13. AS1371 - Block Diagram
AS1371
IN
Shutdown/
Power-On
EN
Control Logic
Thermal
Overload
Protection
-
Error
Amplifier
+
OUT
Trimmable
Reference
Voltage
Bandgap Voltage
&
Current Reference
SENSE
POK
Power-OK
Compare
Logic
NMOS
GND
Output Voltages
Standard products are factory-set with output voltages from 0.6V to 3.3V. A two-digit suffix of the part number identifies
the nominal output (see Ordering Information on page 13). Non-standard devices are available.
For more information contact: http://www.austriamicrosystems.com/contact-us
www.austriamicrosystems.com
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