Low-dropout Voltage Regulator

154

01:34:30

Supplying 5V at 500mA with a dropout of about 0.75V.

Switch for convergence error at start.

The resistor betweent he p-amp and the BJT adjusts the dropout voltage. I can't get it much lower without risking a convergence error when the switch is switched.

published 8 years ago

hurz

8 years ago

But 0.75V is not really a low drop. Anyway, and keep in mind to configure the supply rail settings of OpAmp min max.

eekee

8 years ago

I suppose you're right, hurz. Maybe I'll try common emitter next, like the lower IC here: http://www.linear.com/solutions/1403

hurz

8 years ago

Here we go with a low drop one http://everycircuit.com/circuit/6667948516442112 most simple low drop design are easy to identify by use of an PNP as regulator.

eekee

8 years ago

Oh wow! 120mV drop. Yeah that's low. :) The PnP is common emitter.

hurz

8 years ago

You know why you waste 0.75V at least or even more. A common collector or emitter follower or voltage follower is always loosing Vbe while a common emitter just drops Vce saturation.

eekee

8 years ago

That makes sense.

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