LP5952

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SNVS469F – OCTOBER 2006 – REVISED DECEMBER 2015

Feature Description (continued)

7.3.4 Short-Circuit Protection

The LP5952 is short-circuit protected and, in the event of a peak overcurrent condition, the output current

through the NFET pass device is limited.

If the overcurrent condition exists for a longer time, the average power dissipation increases depending on the

input-to-output voltage difference until the thermal shutdown circuitry turns the NFET off. Refer to Power

Dissipation and Device Operation for power dissipation calculations.

7.3.5 Thermal-Overload Protection

Thermal-overload protection limits the total power dissipation in the LP5952. When the junction temperature

exceeds TJ = 165°C typical, the shutdown logic is triggered, and the NFET is turned off, allowing the device to

cool down. After the junction temperature dropped by 20°C (temperature hysteresis) typical, the NFET is

activated again. This results in a pulsed output voltage during continuous thermal-overload conditions.

The thermal-overload protection is designed to protect the LP5952 in the event of a fault condition. For normal

continuous operation, do not exceed the absolute maximum junction temperature rating of TJ = 150°C (see

Absolute Maximum Ratings).

7.3.6 Reverse Current Path

The internal NFET pass device in LP5952 has an inherent parasitic body diode. During normal operation, the

input voltage is higher than the output voltage, and the parasitic diode is reverse biased. However, if the output is

pulled above the input in an application, the current flows from the output to the input as the parasitic diode gets

forward biased. The output can be pulled above the input as long as the current in the parasitic diode is limited to

50 mA. For currents above this limit an external Schottky diode must be connected from VOUT to VIN (cathode on

VIN, anode on VOUT).

7.4 Device Functional Modes

7.4.1 Enable Operation

The LP5952 may be switched to an ON or OFF state by a logic input at the EN pin, VEN. A logic high at this pin

turns the device on. When the enable pin is low, the regulator output is off, and the device typically consumes

0.1 µA.

If the application does not require the enable switching feature, the EN pin must be tied to VBATT to keep the

regulator output permanently on.

To ensure proper operation, the signal source used to drive the EN input must be able to swing above and below

the specified turnon and turnoff voltage thresholds shown in VIL and VIH in Electrical Characteristics: Enable

Control.

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