MCP1406/07 MOSFET DRIVER

[Jeg]

The most of the times the problem is where i am the most sure of!!! I was so sure that the Cmos gate was ok, that i had put it out of discussion!! Anyway, i had supplied it from the same Vcc (LM7805) that 555 used. I can't think something that could create such a problem! It's output was in the driver's specification range... 

Ah.. actually is a XOR gate 74hc86 but there isn't any difference. I discard it!!!

[TinselKoala]

Well, at the frequency/risetime you are working with it's possible that stray inductances could create high-voltage spiky noise that the driver chip couldn't handle. Between your clock and your mosfet driver, keep leads as short as possible, use proper grounding technique, use a printed circuit board if possible, use bypass capacitors.
Since the direct output of the 555 clock is probably less abrupt in risetime than the output from the logic chip, ironically, it might be easier for the driver to handle because it makes less transient spikes.

[Jeg]

hmm perhaps a low pass filter before the driver's input will solve this driver overdriving. Tnks for the advice

Have you ever worked with many mosfets in series for higher voltage switching?   

[Jeg]

Dear all

I attach a mosfet driver PWM circuit for discussion and learning purposes. I used MCP1406 for fast switching, even i will use it at Audio frequencies.

The circuit uses a 555 and a LM393 comp. for PWM. The timing cap and resistance of 555 will be a pot and few different caps for covering all the audio range with equal Ton and Toff pulse times. (50%). The comp changes the duration of the pulse from about 50%-100%. This is because MCP1406 is an inverting input.

First of all i 'd like to ask about the supply voltages of 555, 393, and 1406 chips. What if MCP1406 would be supplied by 18V and the other two by 5V or 12V. What would be the difference?

An other question is about the pull up resistor of 393 comp. I put a 1.8KOHm for allowing 10mA for the open collector at comp's output, and then 1,8M for allowing maximum 10μΑ for 1406 input. Is that a wrong consideration?

An isolated gate input with pulsed TRansformer also may be included. I intend to use it with a 1000V mosfet (FQA8N100C) or an IGBT at 1200V (HGTG27N120BN)

Any suggestion would be appreciated
Jeg

   

[Jeg]

Here is a way for paralleling voltage regulators for higher current. I think i ll go this way for the supply of MCP1406. 3 regulators are enough for giving up to 6A peak current

http://www.instructables.com/id/Increasing-current-on-78xx-series-regulators/