MCP1702-1502ESLASHMB datasheet(15/32 Pages) MICROCHIP

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DS22008D-page 15

MCP1702

4.0

DETAILED DESCRIPTION

4.1

Output Regulation

A portion of the LDO output voltage is fed back to the

internal error amplifier and compared with the precision

internal bandgap reference. The error amplifier output

will adjust the amount of current that flows through the

P-Channel pass transistor, thus regulating the output

voltage to the desired value. Any changes in input

voltage or output current will cause the error amplifier

to respond and adjust the output voltage to the target

voltage (refer to Figure 4-1).

4.2

Overcurrent

The MCP1702 internal circuitry monitors the amount of

current flowing through the P-Channel pass transistor.

In the event of a short-circuit or excessive output

current, the MCP1702 will turn off the P-Channel

device for a short period, after which the LDO will

attempt to restart. If the excessive current remains, the

cycle will repeat itself.

4.3

Overtemperature

The internal power dissipation within the LDO is a

function of input-to-output voltage differential and load

current. If the power dissipation within the LDO is

excessive, the internal junction temperature will rise

above the typical shutdown threshold of 150°C. At that

point, the LDO will shut down and begin to cool to the

typical turn-on junction temperature of 130°C. If the

power dissipation is low enough, the device will

continue to cool and operate normally. If the power

dissipation remains high, the thermal shutdown

protection circuitry will again turn off the LDO,

protecting it from catastrophic failure.

FIGURE 4-1:

Block Diagram.

MCP1702

VIN

VOUT

GND

+VIN

Error Amplifier

Voltage

Reference

Overcurrent

Overtemperature

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