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TINA/Spice/TIDA-00366: Expected simulation results are not given in TINA TI

Part Number: TIDA-00366
Other Parts Discussed in Thread: TINA-TI, , AMC1301, TEST

Tool/software: TINA-TI or Spice Models

Hello Everyone

I'm Thilesh de Silva From Sri Lanka. I simulated a part of the figure 14. DC bus Voltage sensing circuit in the Design guide of TIDA-00366 using TINA TI latest version. I have attached my simulation file to this description.

Problem is, i expected a differential output from AMC1301 but from the simulation (Steady state solver) the output of VOUTP and VOUTN is look very much similar and when the (Vdc+) - (Vdc-) Voltage is 1100 V it only gives a mV range Output as VOUTP - VOUTN. Accordin to my understanding it should be (VOUTP - VOUTN when the DC bus voltage is 1100 V) very much larger than that. Is there anything wrong in the simulation ? This is the first time i'm using TINA TI.Please explain to me. You'r valuable guidance is highly appreciated. 

 

Rgds

Thilesh DC bus Voltage Sense.TSC

  • Hi Thilesh,

    I'll look over your circuit and get back to you soon.
  • Hi Thilesh,

    Try starting from the AMC1301 TINA-TI Reference Design model (SBAM271.TSC) that you can download from the 'Tools & Software' tab on the AMC1301 product folder. I've seen some strange results in TINA when you use the same ground node for GND1 and GND2 which I sustect are part of the problem you are seeing.
  • Hi Tom

    First I run the simulation for SBAM271.TSC, and the output was exactly as the expected for VOUTP and VOUTN. Then i copied the TINA TI SPICE model from the reference design and paste it in my design. I even changed the VDD1, VDD2, GND1 , GND2 and other ground terminals according to the method used in reference design. Unfortunately the output is look like similar as the first situation. another problem that i noticed is the current in AM1 is flowing towards the Voltage source which is given as 1100 V (VS1 source). could you please help to solve this because i want to modify the design in such a way that it can measure from (-2000 V) to (+2000 V) for my research project. Thank you and looking forward hear from you

    Rgds,

    thilesh

    sbam271.tsc

  • Hi Thilesh,

    Try changing your voltage rails to 5V. We had incorporated a change to the AMC1301 model that included a wider operating voltage. I'll dig into that a little more, but you should see better results with 5V rails. The real chip works fine at 3.3V so no need to worry about that.
  • Hi Tom,

    Thank you for replying me. I've changed the supply rail voltages to 5V ,now the results are little bit improved but not for the satisfactory level. please go through the following simulation states and results.

    1. when the DC bus voltage is 1200 V the voltage seen by the AMC1301 is at steady state is 119.19 mV. Output at the VOUTP is 1.91 V which is not comply with the Gain given in the data sheet (It should be 119.19mV *8.2 = 977.358 mV ). In the same situation the output at the VOUTN is 929.7 mV. If I'm correct the output at the VOUTN should be (-977 mV or closer value with accesptable tolerence)

    2. when the DC bus voltage is 10V  the voltage seen by the AMC1301 is at steady state is (-349.09) mV. According to the data sheet the voltage seen by the  AMC should not be less than (-250) mV. Output at the VOUTP is 178.94 this is not the expected value. If forget about the maximum and minimum values that can be given to the AMC (VOUTP - VOUTN) the value of VOUTP shouls be (-349.09 mV * 8.2 = -2.86 V) In the same situation the output at the VOUTN is 2.66 V. If I'm correct the output at the VOUTN should be (+2.86) V or closer value with accesptable tolerence).

    According to the result from 1 and 2 it seems like VOUTN is atleast close to the actual output which is suppose to be given. Please tell me whether the current reading from the AM1 is correct or wrong ? I've included my simulation file also. Thank you

    Rgds,

    thilesh

    6406.DC bus Voltage Sense.TSC

  • Hi Thilesh,

    Can you adjust your bias on VINN?  With the original 3.3V supply, vbias was ~300mV.

  • Hi Tom,

    Thank you so much now i'm getting the expected output from AMC 1301. could you please look at the following schematic. I've given a general waveform. It change the voltage level from 0 V to 1.2 kV within 3 us. I design the voltage divider in such a way that (VINP - VINN = 220 mV) when the Input Voltage (Voltage of VG1 in the schematic ) is 1.2 kV. But the simulation shows (VINP - VINN) is only 99 mV. could you please tell me whether my calculations are wrong ? I just apply the voltage divider rule and got the ratio as 11 / 60000 then put values to resistors. Same time i inserted a resistor to VINN baranch to avoid the effect of current passing through the measuring resistance (R109 in following schematic ). Please tell me the correct way of calculation or any other modification. Thank you

    Rgds,

    thilesh

    6320.DC bus Voltage Sense.TSC

  • Hi Thilesh,

    You've not done anything wrong schematically, I believe some of the errors you see might be from the model itself. I'm not sure that it accurately depicts the bias current or the input impedance. I'll have the model vendor go through it again and see if they can provide any updates.
  • Hi Tom,

    Thank you for replying me. i'm looking forward to hear from you very soon. This simulation is very important to me because we are developing a high frequency DC to DC converter and most of the components are from Texas Instruments. That is why i chose TINA TI for simulations before go through the prototype and final designs. Thank you and Please update when you receive anything from vendor.

    Rgds,
    thilesh
  • Hi Tom,

    Do you have any updates from the vendor ? I tried the simulation using Spice model. I didn't gave any result because the simulation was aborted due to errors. I don't know what to do. Could you please help me Thank you

    Rgds,
    thilesh
  • Hi Thilesh,

    I've not heard back yet.  I'll try again and see what sort of timeline there might be to get this resolved for you.

  • Hi Thilesh,

    I'm very sorry about the delay on this. I've talked with the vendor and it's going to take them 4-5 weeks to get a revision of the model. In the meantime, if you would like to prototype with the AMC1301 to evaluate/test actual hardware, I can help you acquire some sample devices and/or an evaluation module.