CAB006A12GM3 NTC Thermistor

ankitdesh92

I am using CAB006A12GM3 SiC module which has an inbuilt NTC Thermistor. Where is the temperature sensor placed in the module relative to the SiC FETs. Does it provide case temperature of the SiC Module?Can we estimate the junction temperature of the 2 FETs from the thermistor data?

Forum_Moderator

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Mcolimmah

Hello ankitdesh92,

These are the responses to your questions.

Question 1:Where is the temperature sensor placed in the module relative to the SiC FETs.

Answer: The NTC sensor is placed below the bottom switch of the module as shown by the region marked black in the Figure below.

Question 2: Does it provide case temperature of the SiC Module? 

Answer: Yes, the NTC is closely coupled to the case of the power module. Hence, it can provide the case temperature.  The NTC is good for system sanity checks, such as making sure you have coolant flow, coolant temperature, etc.

Question 3: Can we estimate the junction temperature of the 2 FETs from the thermistor data?

Answer: No, we cannot use the NTC to read the junction temperature of the MOSFETs directly. Since it corresponds to the case temperature. However, with appropriate thermal modeling of the module, using the thermal impedance, and a known power loss, you can roughly estimate the junction temperature.  

Please reach out if you have any more questions.

Thank you,

Marshal Olimmah

ankitdesh92

Thanks for the information. This is really helpful. My objective is to estimate the junction temperature of SiC Module.I have the power losses of the SiC module.I need to have an estimate of thermal resistance between SiC junction (high/low side) and NTC sensor.

1)Is there a CAD model including NTC sensor which I can use with FEA software to estimate this thermal resistance?

2)The data sheet provides thermal resistance junction-heatsink including thermal resistance of TIM.I can estimate thermal resistance junction-case(NTC) by assuming 60% thermal resistance in TIM as per an application note. Is that a decent approximation of thermal resistance of junction-case?

Mcolimmah

Hi ankitdesh92,

(1) Yes, we do have a CAD thermal model which includes the NTC sensor for use in FEA simulation. It, however, is only shared under NDA. If you would like to setup an NDA with Wolfspeed, you can reach out to your sales representative to make the request.

(2) Yes, 60% of the thermal resistance Rth_(Junction-to-Heatsink) is a good estimatate of the Rth_(Junction-to-Case).  

Let me know if you have any other questions. 

Marshal

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.