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Any logic-level FETs with breakdown 300V+?

F

Fred Bartoli

Jan 1, 1970
0
Joerg a écrit :
Well, there ain't so much space left as for a carpenter ant to squish in
there ;-)

You don't need much additional space for this :


|
|
|
|
||-+
||<- HV mosfet
+5V o----->|----+-----||-+
| |
--- |
--- ||-+
| ||<- Logic level
0-5V drive >-------+-----||-+
|
|
===
GND
 
J

Jamie

Jan 1, 1970
0
Fred said:
Joerg a écrit :


You don't need much additional space for this :


|
|
|
|
||-+
||<- HV mosfet
+5V o----->|----+-----||-+
| |
--- |
--- ||-+
| ||<- Logic level
0-5V drive >-------+-----||-+
|
|
===
GND
Not so sure that would be safe for the logic level fet.

The Cap can lead ahead causing the HV fet to turn on
sooner than the logic fet does. HV could thus damage the logic
fet before it gets down in the Ron value.

Also, you have the case where free charge could be on the gate at
initial start up, because I don't see a loading R to prevent that.

Oh well, just my observations from the peanut gallery..

http://webpages.charter.net/jamie_5"
 
L

legg

Jan 1, 1970
0
Not so sure that would be safe for the logic level fet.

The Cap can lead ahead causing the HV fet to turn on
sooner than the logic fet does. HV could thus damage the logic
fet before it gets down in the Ron value.

The HV fet source is not expected to exceed the HV fet gate voltage;
the gate coupling caps are required to be >> greater than Cgs, for
basic function.

RL
 
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