I’ll update the screenshots later The pull-up resistor will have to be sufficiently small in value so that you get an acceptable rise time for your application. You need not more than 17 ohm high drive to obtain reasonable switch time of 50 nS. That is approximately 0. By continuing to use this site, you are consenting to our use of cookies.

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BJT Totem-Pole Power MOSFET driver (Low side) – How and why?

Oscilloscope in Vgs gives an idea how big charge is needed to inject and remove for state transitions in wanted transition time.

Any tweaks we can do on the same circuit to make it more faster. I just reread the wikipedia entry on BJT comon colector emitter follower. Is it a pull-up resistor?.

Want to know more? Sign up or log in Sign up using Google. BJT Wiki The current gain is a good thing because in order to charge the gate capacitance of the FET in a short period of time you need high peak currents: It’s not really floating. I’m wondering if there’s anything else I can do to improve the performance?


Definatly a requirement of the next itteration I think.

Buck using discretes – Driving p-MOSFET using n-MOSFET – Electrical Engineering Stack Exchange

Both caps are 0. I am desperatly in need of education here Sep 13, 9.

CircuitLab doesn’t let me edit the circuit. By using our site, you totfm that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

I’m guessing that what you’re describing would also be relevant in an over-current event. Probably the minimum Vgs is around 0,3 V.

It’s not clear if your signal generator is producing a signal switching between 0 and 5 V or Sep 13, 2. Also, would it make sense to use an opamp instead, such as the LMP?

bjt totem pole

I’ve experimented with different arrangements, with resistors and capacitors. I’m a bit worried that the gate voltage isn’t dropping low enough, e. Particularly as I want to make sure it keeps working. This kinda makes up for the extra BE drop. After Cgs has been drained or Vgamma of pnp is below 0.

Sep 13, 3. I am certainly not trying to be difficalt or obtuce, I apriciate totej help however silly I look, don’t go pulling any punches to spare my feelings, that won’t get me anywhere.


Your two circuits are not the same but Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Bill, we went over that FET in another thread. There is an assumption on my part this will work. At some time, the lower part of the totem pole will turn on untill Cgs is drained.

Vovanium 6 8. I’ll ask SgtWookie to check in and suggest better. I would suggest that the OP does an analysis on how much current he needs to deliver into the gate.

Sep 13, 7.