Timeline for I have a PWM signal that I want to control a heater (3 ohms) with a 36V source. My MOSFETS keep blowing using TC4427
Current License: CC BY-SA 4.0
9 events
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| Sep 11 at 9:34 | comment | added | Robin | Also the TC4427 when the input to it is tri-state can drift up and 'switch-on'. Noticed this in the STM debugger. Thought it was a kind of MOSFET latch-up at first. Recommend a pull down on this! | |
| Sep 11 at 8:11 | comment | added | Robin | I am understanding more about the Gate capacitance. The single 74HC04 output I tried initially ( on the basis is supplied 5V) did not take into account the miller plateau. The Gate is a capacitor that can initially be back driven by Drain current. but the sharp turn off is the remaining problem. | |
| Sep 10 at 20:05 | comment | added | Tyassin | @Robin Yes inductance is unavoidable and needed like a relay, but some remedies like the suggest given here can be used to improve the response. But if you make a real PCB, it will improve. | |
| Sep 10 at 16:42 | comment | added | Carl Rutschow | @Robin--Also connect a 100nF ceramic cap from the point where the diode is connected to the supply, to the MOSFET ground. | |
| Sep 10 at 15:22 | comment | added | Transistor | Tip: 's' = second. 'S' = siemens (unit of conductance = 1 / ohm). Capitals matter! | |
| Sep 10 at 15:22 | comment | added | Robin | the diode goes from Drain to 37 V d.c. (heater supply) | |
| Sep 10 at 15:12 | comment | added | Robin | OK I have a diode back to the plus side of the inductor now and while I am still seeing a spike at turn off it looks much shorter in duration, zooming in on the scope its a ringing of about 100V but duration 1uS | |
| Sep 10 at 14:37 | comment | added | Robin | OK point taken , but the heater in this case will have to go through a cable run. So I am going to have to cope with inductance. At the moment the microchip driver has solved the ON 5uS delay problem but introduced the sharp TURN OFF. I am going to try a diode from the drain to the power supply next I think. | |
| Sep 10 at 14:33 | history | answered | Tyassin | CC BY-SA 4.0 |