aman said:
When I am looking at voltage regulator I come across a term "low drop
out regulator". Can somebody tell me how it is different from a "linear
voltage regulator".
Low drop out regulators are a variant of linear regulators. Most
linears are based on an emitter follower output stage, and usually an
emitter follower driving a bigger emitter follower. This implies a
significant voltage across the regulator to make it function (usually
1.5 to 2 volts). If the pass transistor is connected as a common
emitter (output on the collector) the device may operate below one
diode drop (less than .6 volts) across the regulator. This
configuration is harder to stabilize against oscillations under varied
conditions than the emitter follower configuration is. The base
current for the pass transistor must also go through the reference pin
of the regulator, which makes the current in that pin related to the
load current. The follower configuration has a more stable reference
pin current, making it easier to connect that kind of regulator in an
adjustable output voltage arrangement.
