LP2952-N, LP2952A, LP2953, LP2953A

SNVS095F – MAY 2004 – REVISED MARCH 2015

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Feature Description (continued)

7.3.5

Short-Circuit Protection (Current Limit)

The internal current limit circuit is used to protect the LDO against high-load current faults or shorting events. The

LDO is not designed to operate in a steady-state current limit. During a current-limit event, the LDO sources

constant current. Therefore, the output voltage falls when load impedance decreases. Note also that if a current

limit occurs and the resulting output voltage is low, excessive power may be dissipated across the LDO resulting

in a thermal shutdown of the output. A thermal foldback feature limits the short-circuit current to protect the

regulator from damage under all load conditions. If the OUT pin is forced below 0 V before SHUTDOWN goes

high and the load current required exceeds the thermal foldback current limit, the device may not start up

correctly.

7.3.6 Thermal Protection

The device contains a thermal shutdown protection circuit to turn off the output current when excessive heat is

dissipated in the LDO. The thermal time-constant of the semiconductor die is fairly short, and thus the output

cycles on and off at a high rate when thermal shutdown is reached until the power dissipation is reduced. The

internal protection circuitry of the device is designed to protect against thermal overload conditions. The circuitry

is not intended to replace a proper heatsink. Continuously running the device into thermal shutdown degrades its

reliability.

7.3.7 Automatic Output Discharge

Both LP2952 and LP2953 employ an internal 50-mA (typical) pulldown to discharge the output when the

SHUTDOWN pin is low and the output is disabled.

7.4 Device Functional Mode

7.4.1 Shutdown Mode

When pulling the SHUTDOWN pin to low level, the LP2952 and LP2953 will enter shutdown mode, and a very

low quiescent current is consumed. This function is designed for applications which needs a shutdown mode to

effectively enhance battery life cycle. When the SHUTDOWN pin is low the automatic output discharge circuity

will be active. See Application Information for more details.

7.4.2 Operation with 30 V

voltage may not reach target value.

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Product Folder Links: LP2952-N LP2952A LP2953 LP2953A