Dropout voltage

In electronics, the dropout voltage of a voltage regulator is the smallest possible difference between the input voltage and output voltage to remain inside the regulator's intended operating range.

For example, a regulator with rating of 5v output, 10v input and 2v dropout voltage will only output 5v if the input voltage is 7v (5v+2v). if the input falls below 7v the output will also lower down.

Dropout voltage can be as high as 2V for a typical general purpose integrated circuit regulator (such as the 78xx series), but a low dropout voltage regulator may have a dropout of less than 100mV at full load. Dropout voltage will vary depending on the load on the regulator, usually increasing under higher load, due to the internal resistance of the regulator's pass transistor and circuitry. Dropout voltage also varies under temperature. Dropout voltage will usually be specified over a range of loads and temperatures.

See also

• Low dropout regulator
• Voltage regulator