What is “On/Off” or “Shutdown” on a regulator?
An On/Off or Shutdown feature allows the regulator to be turned on or off while power is applied to its input. While in the Off or Shutdown mode, the regulator”s supply current drops to a low level as the output stage is disabled but the internal bias circuitry is still operational. When turned On again, the regulator regains regulation of the output voltage much more quickly than it would if the input supply voltage had been switched off then on. If there is a bar shown over the “Off” part of On/Off or over “Shutdown”, the regulator is turned on with a logic high.