Driving MOSFET gate from logic outputs
- From: seanacais <kccnospam@xxxxxxxxxxxx>
- Date: Fri, 01 Jun 2007 07:50:59 -0700
Would a common base transistor configuration be a good way to drive
the gate of an N-MOSFET from a logic output?
The MOSFET is the high side of an H-Bridge sitting at about 40V. The
gate will be drawn to 48V which is much too high for logic outputs.
Since I want to run the bridge with high inputs it seems that a common
base configuration would give large voltage amplification in phase
with the inputs. The output of the logic gate would be fed into the
emitter and the collector would hook to the MOSFET gate (and +48V
through a current limiting resistor. I'm not positive but it seems as
if a resistor between the collector and the gate would be a good idea
as well.
In reading about this configuration several references stated that
it's normally used in RF circuits because of the large voltage
amplification. The bridge is to be PWM driven at possible tens of KHz
but nowhere near RF. Is there something I'm missing about this that
would make it unsuitable for this application? Insights, suggestions
and hints are all welcome!
Thanks,
Kevin
.
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