MP62340-1/MP62341-1 –CURRENT-LIMITED POWER DISTRIBUTION SWITCHES

MP62340-1/MP62341-1 Rev.0.9

www.MonolithicPower.com

9

11/2/2009

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© 2009 MPS. All Rights Reserved.

DETAILED DESCRIPTION

Over Current

When the load exceeds trip current (minimum

threshold current triggering constant-current

mode) or a short is present, MP62340-

1/MP62341-1 switches into to a constant-current

mode (current limit value). MP62340-1/MP62341-

1 will be shutdown only if the over current

condition stays long enough to trigger thermal

protection.

Trigger over current protection for different

overload conditions occurring in applications:

1) The output has been shorted or overloaded

before the device is enabled or input applied.

MP62340-1/MP62341-1 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 MP62340-1/

MP62341-1 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 voltage lockout.

Thermal Protection

The purpose of thermal protection is to prevent

damage in the IC by allowing exceptive current to

flow and heating the junction. The die temp. is

internally monitored until the thermal limit is

reached. Once this temp. is reached, the switch

will turn off and allow the chip to cool. The switch

has a built-in hysteresis.

Under-voltage Lockout (UVLO)

This circuit is used to monitor the input voltage to

ensure

that

the

MP62340-1/MP62341-1

is

operating correctly. This UVLO circuit also

ensures that there is no operation until the input

voltage reaches the minimum spec.

Enable

The logic pin disables the chip to reduce the

supply current. The device will operate once the

enable signal reaches the appropriate level. The

input is compatible with both COMS and TTL.

Output Discharge

The part involves a discharge function that

provides a resistive discharge path for the

external output capacitor. The function will be

active when the part is disabled (Input voltage is

under UVLO or enable is deasserted) and it will

be done in a very limited time.