Datasheet

LM2592HV
www.ti.com SNVS075C –MAY 2001–REVISED APRIL 2013
UNDERVOLTAGE LOCKOUT
Some applications require the regulator to remain off until the input voltage reaches a predetermined voltage. An
undervoltage lockout feature applied to a buck regulator is shown in Figure 30, while Figure 31 and Figure 32
applies the same feature to an inverting circuit. The circuit in Figure 31 features a constant threshold voltage for
turn on and turn off (zener voltage plus approximately one volt). If hysteresis is needed, the circuit in Figure 32
has a turn ON voltage which is different than the turn OFF voltage. The amount of hysteresis is approximately
equal to the value of the output voltage. If zener voltages greater than 25V are used, an additional 47 kΩ resistor
is needed from the ON /OFF pin to the ground pin to stay within the 25V maximum limit of the ON /OFF pin.
Figure 30. Undervoltage Lockout for Buck Regulator
This circuit has an ON/OFF threshold of approximately 13V.
Figure 31. Undervoltage Lockout for Inverting Regulator
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