What i want is the FET to completely turn on and off - thereby giving the load a HV pulse.
- Vote on answer
- posted
11 years ago
FET driver not working..why?
Loading thread data ...
- Vote on answer
- posted
11 years ago
AFAIK not stated in the data sheet. Excellent point..thanks.
- Vote on answer
- posted
11 years ago
bootstrap capacitor between VB and VS, on the order of 10x Cin, and as mentioned use fast recovery diode between the VB-VCC. Thanks. That connection was drawn wrong.
- Vote on answer
- posted
11 years ago
Check.
- Vote on answer
- posted
11 years ago
On a sunny day (Sun, 04 Nov 2012 22:48:06 -0800) it happened Robert Baer wrote in :
But in our circuit the fet can ever get higher than 12V. Normally these cicuits work by charging a capacitor via a diode (bootstrap), and for that to happen you both need a hard pulldown PLUS a hard pull up. (totempole, or at east some load to charge / discharge that cap. And that voltage needs to be seen by the driver chip, you connected it wong as others pointed out.
- Vote on answer
- posted
11 years ago
Try this. LTSpice format. Your drawing looks good , so you've obviously corrected it in the mean time. Never tried this with dropbox before , so hope it works.
formatting link
Cheers Ned
- Vote on answer
- posted
11 years ago
It's not. You grounded the low end of the bootstrap cap, and connected
+12 in the wrong place. Well, you did before you changed it.Does it work now?
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
- Vote on answer
- posted
11 years ago
Unlike you, I have never shaved my own foot in my month.
English must be your third language.
- Vote on answer
- posted
11 years ago
His 'Jibberish to English' converter is defective.
- Vote on answer
- posted
11 years ago
Well, he probably "designed" it. What would you expect from a pig (ham) who runs to the ARRL and claims "Daddy! Daddy! .. he picked on me"
- Vote on answer
- posted
11 years ago
The ARRL is probably the bunch who told him that an 'Electret' was a crystal microphone.
- Vote on answer
- posted
11 years ago
Had a more serious problem that totally explained the why: the FET drain was open(!). Schematic has been updated and corrected. Works nice into a 100 ohm resistor as load. Next will be the acid test.. The load will be the B+ (bottom) end of the flyback transformer in the TV set; a 33uF filter cap will be across that load for a closer-to-DC (adjustable) drive.
- Vote on answer
- posted
11 years ago
Only the cap was wrong..
- Vote on answer
- posted
11 years ago
corrected it in the mean time. Never tried this with dropbox before , so hope it works.
"Time step too small; time = 6.47366e-06, timestep = 1.25e-19; trouble with u2:diode25-instance d:u2:_md4_d3 OK"
- Vote on answer
- posted
11 years ago
Yes, but only because i connected the FET drain to the supply..
- Vote on answer
- posted
11 years ago
Go to control panel and set spice engine from normal to alternate.