MCP1792 datasheet(13/32 Pages) MICROCHIP

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DS20006229C-page 13

MCP1792/3

4.0

DETAILED DESCRIPTION

4.1

Device Overview

The MCP1792/3 is an AEC-Q100 qualified LDO

capable of outputting 100 mA of current over the entire

temperature range. The part is stable with a minimum

2.2 µF ceramic capacitor and features a high-voltage

SHDN pin, current foldback protection and extended

working temperature range: -40° to +150°. The device

also features an adequate PSRR of 80 dB typical for

low frequencies and 55 dB for high frequencies.

FIGURE 4-1:

Functional Block Diagram.

An innovative adaptive bias circuitry is used to lower

the power consumption at no load and light loads,

without compromising the dynamic response.

The internal discharge transistor is useful in powering

microcontrollers and other applications that require fast

supply disconnect.

4.2

Output Capacitance Requirements

The

MCP1792/3

requires

minimum

output

capacitance of 2.2 μF for output voltage stability. The

output capacitor should be located as close to the LDO

output as it is practical. The device is designed to work

with low ESR ceramic capacitors. Ceramic materials

X8R\L or X7R have low temperature coefficients and

are well within the acceptable ESR range required.

A typical 2.2 μF X7R 0805 capacitor has an ESR of

50 mΩ. It is recommended to use an appropriate

voltage rating capacitor, and the derating of the

capacitance as a function of voltage and temperature

needs to be taken into account.

For improved transitory behavior over the entire tem-

perature range, a 3.3 μF output capacitor is recom-

mended. The ceramic capacitor type should be X7R or

X8R\L because their dielectrics are rated for use with

temperatures between -40°C to +125°C or -55°C to

+150°C, respectively.

4.3

Input Capacitance Requirements

Low input-source impedance is necessary for the LDO

output to operate properly. When operating on

batteries, or in applications with long lead length

(> 10 inches) between the input source and the LDO,

adding input capacitance is recommended. A minimum

of 2.2 µF to 10 µF of capacitance is sufficient for most

applications. Given the high input voltage capability of

the MCP1792/3, of up to 55V DC, it is recommended to

use an appropriate voltage rating capacitor, and the

derating of the capacitance as a function of voltage and

temperature needs to be taken into account. The

ceramic capacitor type should be X7R or X8R\L

because their dielectrics are rated for use with tem-

peratures between -40°C to +125°C or -55°C to

+150°C, respectively.

P-ch PASS

DEVICE

ERROR

AMP

Feedback

Network

Soft Start

VIN

VOUT

UVLO

Thermal

Shutdown

Bandgap

Reference

(1.218V)

SHDN

Adaptive

Bias

Current

Sense

Short Circuit

Protection

Logic

Control

Enable to

All Blocks

GND

Internally Connected

for parts without SHDN

Discharge

Transistor

RDS = 80

Ω typ

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