The totem pole works fine square waves but not sawtooth. The capacitor should have a few amps peak in it but that only happens with the sqaure wave input.

 

The totem pole works fine square waves but not sawtooth. The capacitor should have a few amps peak in it but that only happens with the sqaure wave input.

Thanks for including your .asc file; it runs on my PC. However, you have mislabeled the 18V DC power source as 25V. Confusing.

I do not understand you: "The capacitor should have a few amps peak in it but that only happens with the sqaure wave input." Please restate what you believe to be wrong.

 

The capacitor should have a few amps peak in it

It will if you use a fatter cap for C2.
Edit: But if C2 represents the gate capacitance of a FET, you can't.
The culprit is the slow (~60uS) falling edge of the OP07 opamp output.

 

As Alec noted, it's the fall-time of your signal.
The peak capacitor discharge current is determined by the rate of change of the signal.
If the capacitor voltage changes essentially as fast as the input signal to the driver, then the driver is doing its job.

 

As Alec noted, it's the fall-time of you signal.
The peak capacitor discharge current is determined by the rate of change of the signal.
If the capacitor voltage changes essentially as fast as the input signal to the driver, then the driver is doing its job.

This totem pole wont work for driving large igbt gates. They should be able to output large peak currents into a capacitive loads.

Whats the issue with this driver?

 

This totem pole wont work for driving large igbt gates. They should be able to output large peak currents into a capacitive loads.

Whats the issue with this driver?

@pager48
As @Alec_t said. The driver can provide 3A or more into a resistor load.

 

Can this BJT totem pole be made to power capacitive large igbt gates?

 

Can this BJT totem pole be made to power capacitive large igbt gates?

Depends upon how large an IGBT gate capacitance and how fast you need to switch it.

 

Depends upon how large an IGBT gate capacitance and how fast you need to switch it.

This totem pole is made of 5amp DC BJTs and it cant put =>2 amps peak into a small 8nf capacitor. It should be able to put much greater peak currents than its 5amp rating.

 

This totem pole is made of 5amp DC BJTs and it cant put =>2 amps peak into a small 8nf capacitor. It should be able to put much greater peak currents than its 5amp rating.

We seem to going in circles here.
It's already been stated that the peak current depends upon the signal rise/fall times.

 

Thats not the case, voltage source set to same voltage as oscillator different currents same frequency.

The totem pole isn't working.

 

The totem pole isn't working.

The capacitor voltage is following the buffer input voltage with very little delay so that's all the totem pole can do.
If you can't understand that, then we seem to be at an impasse.

 

The totem pole is working fine. Expand the trace around the pulse falling edge and you'll see. Your 470n cap has a discharge time of about 14uS and Vbjt is closely following the cap discharge curve. It only needs a few mA to discharge the 10n cap completely in 14uS.

Edit: Crutschow pipped me at the post.

 

Other than a gate driver what other way can a gate be driven from this oscillator? This totem pole doesn't supply the peak current.

 

This totem pole doesn't supply the peak current.

You sound like a broken record (go ahead and ask what's a record), repeating the same thing as if you have no comprehension.
What is this obsession with peak current?
Did you read somewhere you need a particular value of peak current for a particular capacitance and rise-time?
A different driver won't provide any more peak current as the driver is delivering all the current the capacitor requires to charge at the given fall-time.
It's not possible to provide more peak current.
Why can you not understand that?

 

Will a gate driver be able deliver to deliver the peak current?

https://www.diodes.com/assets/Datasheets/ZXGD3005E6.pdf

 

Will a gate driver be able deliver to deliver the peak current?

If you can quantify what peak current you need, and show exactly why you need that particular value, then we can answer the question.

 

If you can quantify what peak current you need, and show exactly why you need that particular value, then we can answer the question.

Switching losses would be high for =>100nC IGBTs using only the ramp generator without delivering peak current into gate of IGBT.

 

Switching losses would be high for =>100nC IGBTs using only the ramp generator without delivering peak current into gate of IGBT.

You are still dealing in generalities.
To do a design you need to list quantitative values for the current you need and how those values were determined, and you haven't.

Tell us the highest sawtooth frequency, and the specific IGBT you will use.

 

IGBT is HGTG11N120CND needs a ramp 80Hz-1.5Khz for an inductive load. Current in collector is ~8amps rms. https://www.onsemi.com/pub/Collateral/HGTG11N120CND-D.pdf

Aren't most gate drivers only a mosfet class AB or totem pole configuration?