LP2982 Datasheet, PDF (14/28 Pages) National Semiconductor (TI) – Micropower 50 mA Ultra Low-Dropout Regulator

LP2982
SNVS128K – MARCH 2000 – REVISED JUNE 2016
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Feature Description (continued)
7.3.4 Low Ground Current
The LP2982 uses a vertical PNP process which allows for quiescent currents that are considerably lower than
those associated with traditional lateral PNP regulators, typically 375 μA at 50-mA load and 80 μA at 1-mA load.
7.3.5 Sleep Mode
When pulling the ON/OFF pin to a low level (V_ON/OFF < 0.15 V), LP2982 enters sleep mode, and less than 1-μA
quiescent current is consumed. This function is designed for the application which needs a sleep mode to
effectively enhance battery life cycle.
7.3.6 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. 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 foldback feature limits the short-circuit current to protect the regulator from damage
under all load conditions. If OUT is forced below 0 V before EN goes high, and the load current required exceeds
the foldback current limit, the device may not start up correctly.
7.3.7 Thermal Protection
The LP2982 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 LM2982 is designed to protect against thermal overload conditions. The
circuitry is not intended to replace proper heat sinking. Continuously running the device into thermal shutdown
degrades its reliability.
7.4 Device Functional Modes
7.4.1 Operation with V_OUT(TARGET) + 1 V ≤ V_IN < 16 V
The device operates if the input voltage is equal to, or exceeds, V_OUT(TARGET) + 0.6 V. At input voltages below the
minimum V_IN requirement, the device does not operate correctly, and output voltage may not reach target value.
7.4.2 Operation With ON/OFF Control
If the voltage on the ON/OFF pin is less than 0.15 V, the device is disabled, and the shutdown current does not
exceed 1 μA. Raising ON/OFF above 1.4 V initiates the start-up sequence of the device.
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