Re: Current Limiting for High side mosfet switch.
- From: Jim Thompson <To-Email-Use-The-Envelope-Icon@xxxxxxxxxxxxxxx>
- Date: Tue, 15 Aug 2006 14:43:38 -0700
On Tue, 15 Aug 2006 21:39:17 GMT, Joerg
<notthisjoergsch@xxxxxxxxxxxxxxxxxxxxx> wrote:
Hello Jim,
Can be as simple as two PNP transistors and a few resistors...
Absolutamente, as long as the limit doesn't have to be very precise. I'd
do it with only one PNP up there and pre-bias it a bit so that the shunt
only drops a couple hundred mV or whatever is acceptable. Then a
resistor from its collector to a FET, NPN or whatever down at logic
level, with a bleeder resistor to GND.
If really hard pressed on the BOM budget there is the option of, gasp,
running the resistor from that PNP's collector right into a CMOS Schmitt
input and let it ease into the VCC substrate diode upon conduction.
Needs a bleeder as well.
If you use two PNP's you lose the temperature problems and can easily
detect accurately a 100mV drop.
...Jim Thompson
--
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