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LP5900

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SNVS358R – JULY 2005 – REVISED JUNE 2016

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Feature Description (continued)

7.3.4 Thermal-Overload Protection

Thermal-overload protection disables the output when the junction temperature rises to approximately 160°C

which allows the device to cool. When the junction temperature cools to approximately 140°C, the output is

enabled. Based on power dissipation, thermal resistance, and ambient temperature, the thermal protection circuit

may cycle on and off. This thermal cycling limits the dissipation of the regulator and protects it from damage as a

result of overheating.

7.4 Device Functional Modes

7.4.1 Operation with Enable Control

The LP5900 may be switched ON or OFF by a logic input at the EN pin. A high voltage at this pin turns the

device on. When the EN pin is low, the regulator output is off, and the device typically consumes 3 nA. However,

if the application does not require the shutdown feature, the EN pin can be tied to IN pin to keep the regulator

output permanently on. In this case the supply voltage must be fully established 500

μs or less to ensure correct

operation of the start-up circuit. Failure to comply with this condition may cause a delayed start-up time of

several seconds.

A 1 M

Ω pull-down resistor ties the EN input to ground, and this ensures that the device will remain off when the

EN pin is left open circuit. To ensure proper operation, the signal source used to drive the EN input must be able

to swing above and below the specified turn-on/off voltage thresholds listed in the Electrical Characteristics

section under VIL and VIH.

7.4.2 Operation with Minimum Operating Input Voltage (VIN)

The LP5900 does not include any dedicated UVLO circuitry. The LP5900 internal circuitry is not fully functional

until VIN is at least 2.5 V. The output voltage is not regulated until VIN ≥ (VOUT + VDO).