MP62550/MP62551 –60mA-1.7A PROGRAMMABLE CURRENT-LIMITED POWER DISTRIBUTION SWITCHES

MP62550/MP62551 Rev. 1.21

www.MonolithicPower.com

11

6/27/2013

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Flag Response

The FLAG

________

pin is an open drain configuration.

When over current or over temperature is

encountered, FLAG

________

will report a fail mode (low

level).

For over current, 7.5ms deglitch time-out is

needed. This is used to ensure that no false fault

signal is reported. This internal deglitch circuit

eliminates the need for components.

For over temperature, the FLAG

________

pin is not

deglitched.

The FLAG

________

will not change state when the input

UVLO is triggered.

Under-voltage Lockout (UVLO)

This circuit is used to monitor the input voltage to

ensure that the MP62550/MP62551 is operating

correctly. This UVLO circuit also ensures that

there is no operation until the input voltage

reaches the minimum spec. Built-in 130mV

hysteresis prevents unwanted on/off power

cycling due to input voltage drop from large

current surges.

Enable

The logic pin disables the chip to reduce the

supply

current.

Enable

high

activate

the

MP62551 while enable low activate the MP62550.

The device will operate once the enable signal

reaches the appropriate level. There is no

hysteresis for enable pin. The input is compatible

with both COMS and TTL.

Thermal Protection

The purpose of thermal protection is to prevent

damage in the IC by allowing exceptive current to

flow and heat the junction. The die temperature is

internally monitored by two independent thermal

sensing circuits until the thermal limit is reached.

The first thermal sensor turns off the power

switch when the die temperature exceeds 135°C

(min) and the part is in current limit. The second

thermal sensor turns off the power-switch when

the die temperature exceeds 155°C (min)

regardless of whether the switch is in current limit.

Both two thermal sensors have built-in hysteresis.

It will turn on the switch once it is cooled down

10°C

approximately.

MP62550/MP62551

continues to cycle off and on until the fault is

removed.