AS1376
Datasheet - Detailed Description
8 Detailed Description
The AS1376 is a low-dropout, low-quiescent-current linear regulator intended for LDO regulator applications where output current load
requirements range from no load to 1A. All devices come with fixed output voltage from 0.5V to 3.3V. (see Ordering Information on page 18).
Shutdown current for the whole regulator is typically 20nA. The device has 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 17, the devices comprise voltage reference, error amplifier, N-channel MOSFET pass transistor, 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 N-channel MOSFET gate is pulled higher,
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 down, allowing less current to pass to the output.
When the adjustable output variant is selected, an external resistor voltage divider is connected to FB pin and a sample of the output is
compared to the 500mV reference.
When a fixed output variant is chosen, FB must be connected to the Output pin. Depending upon the variant chosen, the internal reference is
trimmed to the final output voltage. See Electrical Characteristics (page 4) for final voltages and tolerances.
Figure 17. AS1376 Block Diagram
VIN
AS1376
VIN
VBIAS
QPOWER
-
Error
Amplifier
+
FB
OUT
Reference
Core
Thermal Overload
Protection
RDISCHARGE
EN
Bandgap
Voltage & Current
Reference
Shutdown
Power On
Control Logic
QDISCHARGE
GND
EP
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