LP2983 datasheet(12/25 Pages) TI1

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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 VIN 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 VON/OFF. To prevent

mis-operation, the turnon (and turnoff) voltage signals applied to the ON/OFF input must have a slew rate which

≥ 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 VON/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 VO(NOM) + 1 V ≤ VIN < 16 V

The device operates if the input voltage is equal to, or exceeds, VOUT(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 (IGND) 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.

LP2983 数据表(PDF) 12 Page - Texas Instruments