AS1370 datasheet(12/28 Pages) AMSCO

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[v2-00] 2016-Jun-01

AS1370 − Detailed Description

The AS1370 is a low-dropout, low-quiescent-current linear

regulators intended for LDO regulator applications where

output current load requirements range from no load to 200mA.

The AS1370 also features a Power-OK output to indicate when

the output is within 5% of final value, and also a Shutdown pin.

Shutdown current for the whole regulator is typically 600nA.

The device features integrated short-circuit and over current

protection. Undervoltage 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 170°C. This is a useful

protection when the device is under sustained short circuit

conditions.

Figure 3 shows the block diagram of the AS1370. It identifies

the basics of a series linear regulator employing a P-Channel

MOSFET as the control element. A stable 1.2V voltage reference

(REF in Figure 3) 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.

Output Voltages

Standard products are factory-set with output voltages from

1.2V. A two-digit suffix of the part number identifies the

nominal out (see Ordering Information). Non-standard devices

are available. For more information contact

www.ams.com/contact.

Power-OK Functionality

The AS1370’s Power-OK is built around a N-channel MOSFET.

The Power-OK feature is not active during shutdown and

provides a power-on-reset function that can operate down to

VIN = 1.2V. A capacitor to GND may be added to generate a

power-on-reset delay. To obtain a logic-level output, connect a

pull-up resistor from pin POK to pin OUT. Larger values for this

resistor will help to minimize current consumption; a 100k

resistor is perfect for most applications (see Figure 2).

Detailed Description

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