TIDA-01187: Un expected behavior of Reference design on TINA

Hi Shyam,

Please refer relevant thread: https://e2e.ti.com/support/tools/simulation-hardware-system-design-tools-group/sim-hw-system-design/f/simulation-hardware-system-design-tools-forum/448548/convergence-problem-in-tina

I tried changing the shunt capacitance parameter to 100m as suggested above, and I was able to simulate the circuit. Please let me know if the circuit still doesn't work.

Thanks
Aditya Gosavi

can you please download the file i have attached and do the same, i am seeing abnormal output by doing the setting what you have suggested

Can you please show what kind of output you are getting, and are you doing a DC analysis?

Thanks

Please download file attached and try

Hi, I am getting this waveform for transient analysis:

Thanks

Yes the output misbehaves with input change, convergence issues come with input change, parameter changes, transient parameter changes , voltage rail changes and many

its very difficult to find out, i am doing one by one and adding them and the tool is not made varied input freindly, please close the thread, i will try to find some other ways or tools to simulate properly

thanks for your time

Hi Shyam,

The convergence error is happening because of the C1 capacitor in the circuit. This may happen in simulation when there is no dicharge path for a capacitor. In order to fix this you can connect a resistor of very high value (say 1T ohm so that it doesnot interfere with your simulation result) in parallel with the capacitor C1 for simulation to converge/work.

I have made that change in your tina file and uploading the same here. You can check and try this one.

OPA857+THS4541+TLV3601_Anant.TSC

Regards

Anant

Thanks Anant for your response

Its very difficult, how should identify my self i need to add a big resistance ?

now my doubt is below waveform is due to simulator artifact or due to opamp

ideally the Transformer output should follow the input where as the output is distorted and there by comparator pulse is expanded

5873.OPA857+THS4541+TLV3601_Anant.TSC

I have done one minor modification to the design by taking alarm output to drive two leds which are mutually exclusive, again the simulator throws error with LED2

also please help me how to know that LED is up , i assume LED glow feature is not available in version i am using, but i feel i should be able to put a amm meter and volt meter arround LED1 and 2 to see their mutual exclusivity

Shyam,

I will check and get back to you by tomorrow.

Regards

Anant

Hi Shyam,

I checked your input signal and found out that you are giving a step rise and fall time of 1ns in the current wave form. For such low rise and fall time you need the TIA bandwidth of over 350Mhz. But there OPA857 in low gain mode has bandwidth of 125Mhz only. Hence you are not seeing the correct waveform at the device output. 

If you have to sense such 1ns of rise and fall, you have to use amplifier with higher bandwidth.

You can try using OPA856 or OPA855 which are both >1Ghz GBW.

Regards

Anant Sinha