CRD300DA12E-XM3 Phase Temperature Read

BorjaH

Hi,

I'm trying to measure phases and case temperatures of the CRD300DA12E-XM3 converter and I do not understand the results I'm measuring. Please see attached a screenshot of the read values in ADC units.

I have a couple of questions.

1. I'm trying to read the phase temperatures trough the analog voltages (ADC_A4, ADC_A5 and ADC_C4) instead of the frequency signal. In all cases I'm reading 0 in ADC units, which I assume is 0V. According to Table 5 of the user guide, this corresponds with a temperature less than 0ºC, which makes no sense.
2. For the case temperature I'm reading 2545 in ADC units, which I assume that corresponds to 1.86V (assuming a 0-3V range for 0-4095 ADC range). Is this right? If I substitute 1.86V in equation 2, this gives me a case temperature of 304.1K (30.95 ºC), which makes sense for me.

Best regards,

Borja

Forum_Moderator

Thank you for your post, it has been approved and we will respond as soon as possible.

JHayes

Hi Borja,

Are the gate drivers powered on in the unit?

Are you using the provided Wolfspeed firmware? or are you implementing your own?

Thanks,

Jonathan

BorjaH

Hi Jonathan,

I'm implementing the software by self. Just a dummy Simulink model to check all C2000 interfaces.

You’re right. Gate drivers were not powered. Just after activating PSDIS signals from the LaunchPad, I’m able to read phase temperature values. See image below.

Could you also provide us how phase temperature measurements are scaled in ADC units? Does is map 0-3V voltage range into 0-4095 ADC units?

The same question for the case temperature?

Best regards,

Borja

JHayes

Ok great - just for your information, there is circuitry on the gate drivers to bias the NTCs and then send an isolated PWM encoded signal back to the controller board, which is then filtered into the ADCs.

You are correct, the ADC inputs are 0-3V and map to 0-4095 in the ADC result registers.

For reference, below is the code Wolfspeed provides to translate the Case temp and Phase temp to a temperature in Kelvin. You can see based on the ADC result, the resistance of the NTC is calculated and then translated to a temperature based on the NTC equations provided in the module datasheet.

Thanks,

Jonathan

BorjaH

Hi Jonathan,

Many thanks for the reference code. Really appreciated.

Regards,

Borja

TBhatia

Hi, I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.