CAB5R0 NTC location in the power module

Prathik

Hello,

I just wanted to find out where in the CAB5R0 SiC MOSFET module the NTC thermistor is placed? Does it measure the hotspot temperature of the power module? How far off is the actual junction temperature from the temperature of the measurement point of the NTC?

Forum_Moderator

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

AustinC

Hi Prathik,

I've included an image of the internal module layout for the CAB5R0A23GM4 below to make the placement of the thermistor clear in relation to the SiC MOSFET die. As is standard with thermistors in power modules, the temperature of the NTC is more indicative of the substrate/baseplate temperature and is only loosely correlated to the die's junction temperature. For this reason, most users choose to utilize the NTC as a safety limit switch to detect an issue with the cooling system such as coolant flow blockage or heatsink fans not running as opposed to a precise temperature feedback of the die's junction temperature.

Best Regards,

Austin C.

Prathik

Hi Austin,

Thank you for the explanation. I think what this means is the temperature indicated by the NTC is closer to the temperature of the heatsink (or a few degrees above it) and cannot reliably be used for the junction overtemperature protection.

At full power dissipation, how much hotter can I expect the NTC to be than the temperature of the heatsink that the module sits on so that I can implement some form of overtemperature protection based on what I know will be the maximum heatsink temperature in the worst case scenario?

Thanks,

Prathik