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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 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
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
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
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.