LP5951

SNVS345F – JUNE 2006 – REVISED MAY 2013

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NO-LOAD STABILITY

The LP5951 will remain stable and in regulation with no external load. This is an important consideration in some

circuits, for example CMOS RAM keep-alive applications.

ENABLE OPERATION

the device on. When the enable pin is low, the regulator output is off and the device typically consumes 5nA.

regulator output permanently on.

below the specified turn-on/off voltage thresholds listed in the Electrical Characteristics section under Enable

FAST TURN OFF AND ON

The controlled switch-off feature of the device provides a fast turn off by discharging the output capacitor via an

internal FET device. This discharge is current limited by the RDSon of this switch.

Fast turn-on is ensured by an optimized architecture allowing a very fast ramp of the output voltage to reach the

target voltage.

SHORT-CIRCUIT PROTECTION

The LP5951 is short circuit protected and in the event of a peak over-current condition, the output current

through the PMOS will be limited.

If the over-current condition exists for a longer time, the average power dissipation will increase depending on

the input to output voltage difference until the thermal shutdown circuitry will turn off the PMOS.

Please refer to the Thermal Properties section for power dissipation calculations.

THERMAL-OVERLOAD PROTECTION

Thermal-Overload Protection limits the total power dissipation in the LP5951. When the junction temperature

down. After the junction temperature dropped by 20°C (temperature hysteresis), the PMOS is activated again.

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

The Thermal-Overload Protection is designed to protect the LP5951 in the event of a fault condition. For normal,

Absolute Maximum Ratings).

REVERSE CURRENT PATH

The internal PFET pass device in LP5951 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, then 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

50mA.

EVALUATION BOARDS

For availability of evaluation boards, see the LP5951 product folder. For information regarding evaluation boards,

see the TI AN-1486 Application Report (SNVA169).

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