LP2952 datasheet(16/22 Pages) NSC

16 / 22 page

Application Hints (Continued)

SHUTDOWN INPUT

A logic-level signal will shut off the regulator output when a

“LOW” (<1.2V) is applied to the Shutdown input.

To prevent possible mis-operation, the Shutdown input must

be actively terminated. If the input is driven from open-

collector logic, a pull-up resistor (20 k

Ω to 100 kΩ recom-

mended) should be connected from the Shutdown input to

the regulator input.

If the Shutdown input is driven from a source that actively

pulls high and low (like an op-amp), the pull-up resistor is not

required, but may be used.

If the shutdown function is not to be used, the cost of the

pull-up resistor can be saved by simply tying the Shutdown

input directly to the regulator input.

IMPORTANT: Since the Absolute Maximum Ratings state

that the Shutdown input can not go more than 0.3V below

ground, the reverse-battery protection feature which protects

the regulator input is sacrificed if the Shutdown input is tied

directly to the regulator input.

If reverse-battery protection is required in an application, the

pull-up resistor between the Shutdown input and the regula-

tor input must be used.

Typical Applications

Basic 5V Regulator

01112715

5V Current Limiter with Load Fault Indicator

01112716

* Output voltage equals +VIN minum dropout voltage, which varies with

output current. Current limits at a maximum of 380 mA (typical).

** Select R1 so that the comparator input voltage is 1.23V at the output

voltage which corresponds to the desired fault current value.

Low T.C. Current Sink

01112717

LP2952 Arkusz danych(PDF) 16 Page - National Semiconductor (TI)