MP62180/MP62181 –CURRENT-LIMITED POWER DISTRIBUTION SWITCH

MP62180_MP62181 Rev. 0.9

www.MonolithicPower.com

7

2/23/2010

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© 2010 MPS. All Rights Reserved.

FUNCTION BLOCK DIAGRAM

Vref

Deglitch

Logic

Charge

Pump

GND

*: EN is active high for MP62181; EN is active low for MP62180

Thermal

Sense

UVLO

IN

EN*

FLAG

OUT

Current

Sense

AMP

--

+

+

--

Figure2—Function Block Diagram

DETAILED DESCRIPTION

Over Current

When the load exceeds trip current (minimum

threshold current triggering constant-current

mode) or a short is present, MP62180/MP62181

switches into to a constant-current mode (current

limit value). MP62180/MP62181 will be shutdown

only if the overcurrent condition stays long

enough to trigger thermal protection.

Trigger

overcurrent

protection

for

different

overload conditions occurring in applications:

1) The output has been shorted or overloaded

before the device is enabled or input applied.

MP62180/MP62181 detects the short or

overload and immediately switches into a

constant-current mode.

2) A short or an overload occurs after the device

is enabled. After the current-limit circuit has

been tripped (reached the trip current

threshold), the device switches into constant-

current mode. However, high current may

flow for a short period of time before the

current-limit circuit can react.

3) Output current has been gradually increased

beyond the recommended operating current.

The load current rises until the trip current

threshold is reached or until the thermal limit

of

the

device

is

exceeded.

The

MP62180/MP62181 is capable of delivering

current up to the trip current threshold without

damaging the device. Once the trip threshold

has been reached, the device switches into

its constant-current mode.

Flag Response

The FLAG pin is an open drain configuration.

This FAULT will report a fail mode after an 8ms

deglitch timeout. This is used to ensure that no

false fault signals are reported. This internal

deglitch circuit eliminates the need for extend

components. The FLAG pin is not deglitched

during an over temp. or a voltage lockout.