AS1364

Datasheet - Detailed Descr i pti on

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Revision 1.8

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8 Detailed Description

The AS1364 output voltage is factory-trimmed or is adjustable from +1.2V to +5V, and is guaranteed to supply 1A of output current. The device

consists of a +1.20V internal reference, error amplifier, MOSFET driver, P-channel pass transistor, internal feedback voltage-divider and a

comparator (see Figure 16).

Figure 16. AS1364 - Block Diagram

Figure 16 shows the block diagram of the AS1364. It identifies the basics of a series linear regulator employing a P-Channel MOSFET as the

control element. A stable voltage reference (1.2V REF in Figure 16) is compared with an attenuated sample of the output voltage. Any difference

between the two voltages (reference and sample) creates an output from the error amplifier that drives the series control element to reduce the

difference to a minimum. The error amplifier incorporates additional buffering to drive the relatively large gate capacitance of the series pass P-

channel MOSFET, when additional drive current is required under transient conditions. Input supply variations are absorbed by the series

element, and output voltage variations with loading are absorbed by the low output impedance of the regulator.

When in shutdown, a 5k

 discharge path is connected between the output terminal and ground.

1

AS1364

+

–

+

–

+

–

100mV

+

–

4.7µF

+

–

4

IN

6

OUT

2

EN

POK

7

SET/BYP

8

GND

4.7µF

Shutdown

Logic

MOSFET

Driver

Thermal

Sensor

2.0V to 5.5V

Logic Supply Voltage

To Controller

Error

Amplifier

On

Off

1.20V

Reference

1.2V to 5.0V

3

IN

5

OUT