Post as a guest Name. Sep 15, I tried to change the R1 2K to and VG1 1. I made the following circuit, not realizing that the gate voltage would never be more than the input signal voltage. Your double emitter follower therefore has a 2 junction drop about 1.

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

An OpAmp has following drawbacks: If this voltage goes above 6. Q2 is hevily overdriven.

That’s why you should not drive with resistive pullup. In an actual IC, M2 and M3 would be sized small enough to have high enough Rds-on instead of putting actual resistors. Your BJTs are in a follower configuration. Q1 is a simple inverting level translator to get the signal mosfft to 12 Volts.

I usuully use line drivers for current buffering No, create an account now. After Cgs has been drained or Vgamma of pnp is ,osfet 0.

Sep 13, Ib will be inherrently limmited because once the turn on threshold is reached any aditional ‘potential’ current will be Iec. Sep 13, 9. That is approximately 0.


Sep 13, 8. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register. Sign up using Email and Password.

If you want to pull it down, you need a something to turn the transistor on with and I’m not sure that TL accepts bmt higher than GND on the emitter pin, you might need to look for another solution.

bjt totem pole

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. So when one transistor is turned on, the other is turned off. Sounds like you really want to do a discrete driver. I would suggest that the OP does an analysis on how much current he needs to deliver into the gate. Which in turn makes output to 12V always.

That determines the wanted drive current.

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

This means that they can provide current gain, but not voltage gain. Yes Bill thats about the size of it The IR is a good choice too.


Posted by mushahid in forum: 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: At the other end, its usually easy enough to drive GATE the mofet mV further than what you want to make sure shows up on the gate of Q3. Its offset starts at about 2V and increases with input voltage to about 5V.

You must use the final load.

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

Please write a comment. What is the purpose of this pull up resistor in totem pole? Note that this double emitter follower will loose mV or so on each end. I’m mixing them because I dont understand, sorry, I wish I did.