LP2983 Datasheet, PDF (12/25 Pages) National Semiconductor (TI) – Micropower 150 mA Voltage Regulator in SOT-23 Package For Output Voltages 1.2V Designed for Use with Very Low ESR Output Capacitors

LP2983
SNVS170D – OCTOBER 2001 – REVISED APRIL 2016
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Feature Description (continued)
7.3.4 ON/OFF Input Operation
The LP2983 is shut off by driving the ON/OFF input low, and turned on by pulling it high. If this feature is not to
be used, the ON/OFF input must be tied to V_IN to keep the regulator output on at all times.
To assure proper operation, the signal source used to drive the ON/OFF input must be able to swing above and
below the specified turnon or turnoff voltage thresholds listed in Typical Characteristics under V_ON/OFF. To prevent
mis-operation, the turnon (and turnoff) voltage signals applied to the ON/OFF input must have a slew rate which
is ≥ 40 mV/µs.
CAUTION
The regulator output voltage can not be ensured if a slow-moving AC (or DC) signal is
applied that is in the range between the specified turn-on and turn-off voltages listed
under the electrical specification V_ON/OFF (see Electrical Characteristics).
7.3.5 Thermal Protection
The LP2983 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 LM2983 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_O(NOM) + 1 V ≤ V_IN < 16 V
The device operates if the input voltage is equal to, or exceeds, V_OUT(TARGET) + 1 V. If the previous condition is
not met, the device will not operate correctly, and the 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 0.1 V at room temperature and less than 0.05 V over the full
operating temperature range, the device output is disabled, and the shutdown current (I_GND) will not exceed 12
μA. Raising ON/OFF above 1.4 V at room temperature and above 1.6 V over the full operating temperature
range initiates the start-up sequence of the device.
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