Re: Common collector load driver
- From: d.frasca@xxxxxxxxxxxxx
- Date: Tue, 6 May 2008 07:24:14 -0700 (PDT)
On May 5, 7:05 pm, Jamie
<jamie_ka1lpa_not_valid_after_ka1l...@xxxxxxxxxxx> wrote:
rich wrote:
Hello all,
I need to to drive a 300mA resistive load with an variable voltage
of 0-30V. Right now I have a NPN transistor in the common collector
configuration.
The collector is tied to the supply voltage which can be 10-30V. The
base is driven from 0V up to the supply voltage.
This works just fine up to a supply voltage of about 20V. I can vary
the base voltage from zero to that and get a nice output without too
much heat.
Above this however I get way to much heat, even at small loads.
The transistor is in a sot-223 package with a pcb copper pour area as
a heatsink.
What is a better way to construct a voltage follower that will
dissipate less heat? Perhaps switching to a p-channel mosfet?
Thanks
Rich
that's because you're creating to much resistance in the transistor keep
the voltage down on low levels when loaded.. This translates to heat.
When using lower input voltages, the transistor is at a lower
resistant value and thus, less heat.
A Buck regulator will correct for this error.
http://webpages.charter.net/jamie_5";
Rich,
Can you give us a little more info as what the load is and what your
driving it with. It seems to me the ans. are getting a little complex
for all we know it might be just changing the brightness of a lamp.
Dennis
.
- References:
- Common collector load driver
- From: rich
- Re: Common collector load driver
- From: Jamie
- Common collector load driver
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