Low-Dropout Regulator

124

01:21:28

Got it right this time.

Drop @ 18.8mA: 50mV to 1.98V

Drop vs. max. current:
50mV    18.7mA
1.98V     607mA

At 50mV drop, regulation is absent beyond 18.8mA (266R). Doubling forward beta does not bring it up to 20ma. Negative supply to the op-amp would help, but the additional demand of a negative supply seems bad in a low-dropout regulator.

It can't regulate with no load, but 100kΩ (included) is fine so long as op-amp can swing close to +Vin. 

Too high slew rate causes problems. Fixed with RC filter.

Relay for simulation only.

Transistor's internal resistances reduced to 10mΩ (except base).

published 7 years ago

eekee

7 years ago

Now I wonder if the design might have been easier with the output decoupled.

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