piclist 1998\10\01\193220a >
Thread: 5V low dropout regulator???
face BY : paulb@EraseMEmidcoast.com.au

Sean Breheny wrote:

> When you paralleled these, did you need any ballast resistors?  What
> kind of pass transistor do these regs. have internally?  Is it bipolar
> or CMOS. If bipolar, I would think that you would need the ballast
> resistors for temperature stability (unless the reg has its own
> internal temp compensation which is good enough) and to handle small
> diferences in the gain of the transistors.

 I don't think so.  Notwithstanding the internal construction, most
regulators are designed to current limit, and to taper the limit current
according to temperature.  As such, the regulator whose setpoint
(voltage) is higher will provide as much current as it chooses, allowing
the other to make up the balance.

 A bit crude, but much like paralleling a regulator with a resistor to
"ballast" most of the current if you can predict the load, as is done in
most TV sets!
       Paul B.

<36141015.7A60@midcoast.com.au> 7bit

See also: www.piclist.com/techref/index.htm?key=low+dropout+regulator
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