LP2989LV_15 Datasheet, PDF (10/26 Pages) Texas Instruments – Micropower and Low-Noise, 500-mA Ultra Low-Dropout Regulator for Use With Ceramic Output Capacitors

LP2989LV
SNVS086K – MAY 2000 – REVISED JULY 2015
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Feature Description (continued)
7.3.5 Thermal Protection
The device 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 device 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 16 V ≥ V_IN > V_OUT(TARGET) + 1 V
The device operates if the input voltage is equal to, or exceeds V_OUT(TARGET) + 1 V. At input voltages below the
minimum V_IN requirement, the devices does not operate correctly, and output voltage may not reach target value.
7.4.2 Operation with Shutdown Control
If the voltage on the SHUTDOWN pin is less than 0.18 V, the output is ensured to be OFF. When the voltage on
the SHUTDOWN pin is more than 1.6 V the output is ensured to be ON. Operating with the SHUTDOWN pin
voltage between 0.18 V and 1.6 V is strongly discouraged as the status of the output is not ensured.
7.4.3 Shutdown Input Operation
The LP2989LV is shut off by driving the SHUTDOWN pin low, and turned on by pulling it high. If this feature is
not to be used, the SHUTDOWN 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 Shutdown input must be able to swing above and
below the specified turn-on/turn-off voltage thresholds listed in Electrical Characteristics under V_SD.
To prevent mis-operation, the turnon (and turnoff) voltage signals applied to the SHUTDOWN input must have a
slew rate which is ≥ 40 mV/µs.
CAUTION
The regulator output voltage cannot 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_SD (see Electrical Characteristics ).
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