MCP1754S datasheet(17/42 Pages) MICROCHIP

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DS22276A-page 17

MCP1754/MCP1754S

4.0

DEVICE OVERVIEW

The MCP1754/MCP1754S is a 150 mA output current,

Low Dropout (LDO) voltage regulator. The low dropout

voltage of 300 mV typical at 150 mA of current makes

it ideal for battery-powered applications. The input

voltage range is 3.6V to 16.0V. Unlike other high output

current LDOs, the MCP1754/MCP1754S typically

draws only 150 µA of quiescent current for a 150 mA

load. The MCP1754 adds a shutdown control input pin

and a power good output pin. The output voltage

options are fixed.

4.1

LDO Output Voltage

The MCP1754/MCP1754S LDO has a fixed output

voltage. The output voltage range is 1.8V to 5.5V.

4.2

Output Current and Current

Limiting

The MCP1754/MCP1754S LDO is tested and ensured

to supply a minimum of 150 mA of output current. The

MCP1754/MCP1754S has no minimum output load, so

the output load current can go to 0 mA and the LDO will

continue to regulate the output voltage to within

tolerance.

The MCP1754/MCP1754S also incorporates a true

output current foldback. If the output load presents an

excessive load due to a low impedance short circuit

condition, the output current and voltage will fold back

towards 30 mA and 0V respectively.

The output voltage and current will resume normal

levels when the excessive load is removed. If the

overload condition is a soft overload, the MCP1754/

MCP1754S will supply higher load currents of up to

typically 250 mA. This allows for device usage in

applications that have pulsed load currents having an

average output current value of 150 mA or less.

Output overload conditions may also result in an over-

temperature shutdown of the device. If the junction

temperature rises above 150°C (typical), the LDO will

shut

down

the

output.

See

Section 4.8

“Overtemperature Protection” for more information

on overtemperature shutdown.

4.3

Output Capacitor

The MCP1754/MCP1754S requires a minimum output

capacitance of 1 µF for output voltage stability. Ceramic

capacitors are recommended because of their size,

cost and environmentally robust qualities.

Aluminum-electrolytic and tantalum capacitors can be

used on the LDO output as well. The Equivalent Series

Resistance (ESR) of the electrolytic output capacitor

should be no greater than 2.0

Ω. The output capacitor

should be located as close to the LDO output as is

practical. Ceramic materials X7R and X5R have low

temperature coefficients and are well within the

acceptable ESR range required. A typical 1 µF X7R

0805 capacitor has an ESR of 50 milliohms.

Larger LDO output capacitors can be used with the

MCP1754/MCP1754S

improve

dynamic

performance

and

power

supply

ripple

rejection

performance.

maximum

1000 µF

recommended. Aluminum-electrolytic capacitors are

not recommended for low temperature applications of

< -25°C.

FIGURE 4-1:

Typical Current Foldback.

Typical Current FoldBack - 5V Output

Increasing Load

Decreasing Load

0.000

0.050

0.100

0.150

0.200

0.250

OUT (A)

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