OPA548: OPA548

Hi Kay,

        Questions:

1. I think we should start with power op amps for your application:  https://www.ti.com/amplifier-circuit/op-amps/power/products.html  
2. What supply range are you looking for on your amplifier? 
3. You mention a slew rate of 200ns.  What is the rate of change of voltage over time  (i.e. V/μs)?  Slew rate is a large signal event (step sizes above 100mV).  What is your step size?
4. What do you mean by "Output current should be more"?  How much output current is required?

        Replies:

1. we will check this link
2. 12V supply range
3. I mean the switching speed of the MOSFET - 200ns
4. Output current to charge the MOSFET gate to turn on the MOSFET. Expecting the output current more than 2A

Regards,

R SRI RAJA SUMAN

Hi Sri, 

Art is OOO today. I still have several questions about your requirements. Once you tell us what the design is needed, I can provide you with the simulation. 

SRI RAJA SUMAN R said:

You mention a slew rate of 200ns.  What is the rate of change of voltage over time  (i.e. V/μs)?  Slew rate is a large signal event (step sizes above 100mV).  What is your step size?

Assume that the application is required to have fast ramp rate in 200nsec. What is output step size?

For instance, 0 to 0.2V output step size in 200nsec, it will require 0.2V/200nsec = 1V/usec

SRI RAJA SUMAN R said:

I mean the switching speed of the MOSFET - 200ns

Most NMOSFET with low gate to source parasitic capacitance should be able to switch at 200nsec. For instance, the following nmosfet may work for the application. TI also has power NMOSFET to drive the application. 

https://www.infineon.com/dgdl/Infineon-IRFZ44N-DataSheet-v01_01-EN.pdf?fileId=5546d462533600a40153563b3a9f220d

https://www.ti.com/power-management/mosfets/products.html?keyMatch=power%20mosfet%20selection#sort=1811;asc&

SRI RAJA SUMAN R said:

Output current to charge the MOSFET gate to turn on the MOSFET. Expecting the output current more than 2A

This will not be issues. 

SRI RAJA SUMAN R said:

What supply range are you looking for on your amplifier? 

Per the V-to-I current converter, you do not need power amplifier to drive the application. What is your 2A ± %error  for the driving application? What is the input voltage to current  convert for the application? What is the required slew rate per the application. Is the current source switched in square wave or other waveform? What type of load is the application driving?

Below is an example, but the OPA192's slew rate is not high enough, and the example is operating at 100kHz. Please specify the actual requirements. If the slew rate requirement is extremely high, you may have to go to High Speed op amp team for the support. 

Best,

Raymond