LP2985LV Datasheet, PDF (11/15 Pages) National Semiconductor (TI) – Micropower 150 mA Low-Noise Low-Dropout Regulator in SOT-23 and micro SMD packages for Applications

LP2985LV
150ĆmA LOWĆNOISE, LOWĆDROPOUT REGULATOR
WITH SHUTDOWN FOR OUTPUT VOLTAGES <2.3 V
SLVS552 − OCTOBER 2004
APPLICATION INFORMATION
ON/OFF operation
The LP2985LV allows for a shutdown mode via the ON/OFF pin. Driving the pin LOW (≤0.3 V) turns the device
OFF, conversely, a HIGH (≥1.6 V) turns the device ON. If the shutdown feature is not used, the ON/OFF pin
should be connected to the input to ensure that the regulator is on at all times. For proper operation, do not leave
the ON/OFF pin unconnected and apply a signal with a slew rate of ≥40 mV/µs.
reverse input-output voltage
There is an inherent diode present across the PNP pass element of the LP2985LV.
VIN
VOUT
With the anode connected to the output, this diode is reverse biased during normal operation since the input
voltage is higher than the output. However, if the output is pulled higher than the input for any reason, this diode
will be forward biased and can cause a parasitic silicon-controlled rectifier (SCR) to latch, resulting in high
current flowing from the output to the input. Thus, to prevent possible damage to the regulator in any application
where the output may be pulled above the input, an external Schottky diode must be connected between the
output and input. With the anode on output, this Schottky limits the reverse voltage across the output and input
pins to 0.3 V, preventing the regulator’s internal diode from forward biasing.
Schottky
VIN
VOUT
LP2985LV
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265
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