To know the junction temperature, According to Datasheet, I need to measure the temperature of exposed thermal pad.
It shows"Measuring the temperature as close as possible to the exposed thermal pad is recommended."（P24 of datasheet）
But I don't know how to measure the exposed thermal pad at the bottom of DRV401 which has been mounted on the PCB. I think I can only measure temperature of Pin-GND1(short to thermal pad ).
Could you tell me whether this method of measurement is right?
Hi Zhun Liu,
I will give my recomendations with the assumptions that you will be using an IC (local) temperature sensor.
1. Add vias to the thermal pad area and mount the temperature monitor on the bottom side of the PCB, directly below the heat source. Vias are a highly effective method for transferring heat quickly from one side of the PCB to the other because of the superior thermal conductivity of copper compared to FR4.
Figure 1: Sensor Mounted On Opposite Side Of Heat Source; Multiple Vias Ensure Fast Heat Transfer
2. If it is not practical or cost effective to place the temperature sensor on the opposite side of the heat source, place it on the same side as close as possible to it. The most effective way of creating a thermal equilibrium between the heat source and the temperature monitor is through the ground plane. Use a solid ground plane that extends from the heat source to the temperature sensor.
Figure 2: Shared GND Plane Helps With Thermal Equilibrium
You can find detailed information of this recommendations in the following app note:
