Timeline for How to remove turn on ringing/overshoot in MOSFET output for 1 MHz and 70V Switching?
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
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| May 1 at 4:28 | comment | converted from answer | Syed Mishar Newaz | I had made a DIY constant current dummy load using IRFZ44N a while back, around 3 years ago. It had been working great. Just some days ago, the device suddenly stopped working. After inspecting, I found that the MOSFET was shorted. I suspected that it was due to the ringing peak exceeding V_gs_max. After probing with a modded cheap PC oscilloscope, I confirmed that it was actually the case. The peak exceeded 23V, whereas the V_gs_abs_max for IRFZ44 is 20V. After replacing the MOSFET, I was searching for some ideas to stop burning the MOSFET again. Finally, I used 12V zener in reverse bias and | |
| Nov 25, 2017 at 1:58 | answer | added | delanymichael | timeline score: 0 | |
| Nov 24, 2017 at 3:02 | comment | added | Zahi Azmi | @RussellMcMahon Thank, i'll try your advice | |
| Nov 24, 2017 at 3:02 | comment | added | Zahi Azmi | @MarkoBuršič I will use it for a ultrasonic transducer for railway damage detection | |
| Nov 24, 2017 at 3:00 | comment | added | Zahi Azmi | @HarrySvensson , there is no any signal if i put the 1 MOhm resistor series with the gate | |
| Nov 23, 2017 at 14:21 | answer | added | user1956035 | timeline score: 1 | |
| Nov 23, 2017 at 13:54 | comment | added | Russell McMahon♦ | Gate drive R of about 10 Ohms to damp ringing. | Small Schottky diode across FET gs as near as FET as possible. Cathode to gate so diode conducts when gate goes negative. Ringing gate has negative excursions clamped. | Zener gs - Vzener > V2 and usefully less than Vgsmax. | Small ferrite bead on source lead - getting desperate. | Is R2 inductive? | |
| Nov 23, 2017 at 9:56 | answer | added | Rohat Kılıç | timeline score: 5 | |
| Nov 23, 2017 at 9:48 | comment | added | Whit3rd | There has to be some inductance (or an unshielded probe) to make such overshoot. The circuit as shown can't get 50V above that 70V rail. Reroute the probe wiring, and put a second probe on the power supply. | |
| Nov 23, 2017 at 8:44 | comment | added | Marko Buršič | Hi, pal. Putting a MOSFET to 1MHz operation is quite difficult task. Anyway, what this circuit does? Where is the load? | |
| Nov 23, 2017 at 7:12 | comment | added | Harry Svensson | That oscilloscope image is without any resistor between V2 and M1, right? - How does the oscilloscope look if you put the 1 MΩ as in you described? It would be nice to see if there's any difference at all. | |
| Nov 23, 2017 at 7:01 | history | edited | Zahi Azmi | CC BY-SA 3.0 |
added 128 characters in body
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| Nov 23, 2017 at 5:34 | history | asked | Zahi Azmi | CC BY-SA 3.0 |