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GKIM
Level 1
Level 1
First like received First question asked Welcome!

Hello,

We are using the Power MOSFET IPB083N15N5LF in our power supply product.

I have a question on the safe operating temperature range measured on the package top face.

In our product the bottom tab is mounted on the heatsink.

When I measure the temperature at the package top face by using a thermocouple under the rated load, it is measured as 73 for the environmental temperature of 27.

Therefore we suppose that the temperature at the package top face under the rated load would be 96 and 117 for the environmental temperature of 50 and 71 respectively.

I wonder how much the Power MOSFET IPB083N15N5LF is safe when the temperature at the package top face is measured as 96 and 117 respectively.

Thank you for your guidance.

With regards,

 GKIM

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1 Solution
sushank
Moderator
Moderator
Moderator
25 solutions authored 100 sign-ins 50 replies posted

Hello @GKIM ,

The device can operate safely upto a junction temperature of Tj-150degC. But to estimate the junction temperature based on external case temperature, we would also need the total power dissipation information. 

Additionally, the major heat dissipation path would be through the heatsink. Hence, the reliable way of estimating the junction temperature would be using the temperature of the heat sink. Rthja value for the device is provided in the datasheet for two layout conditions. You can consider the Rthja that is applicable for your application based on the footprint used and the Tj can be calculated as below. 

Rth of heatsink(( heatsink datasheet parameter)) - Rthch 

Junction to ambient( PCB) for a given footprint (datasheet value) - Rthja

Tj- Th = Pd( Rthja+Rthch) , where Th - heatsink temperature. 

Can you please let me know if you have the measurement data of the heat sink temperature. Please share us below information to estimate the Pd.

1. Converter topology

2. Input & Output ratings

3. Switching frequency

Regards

Meghana

 

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1 Reply
sushank
Moderator
Moderator
Moderator
25 solutions authored 100 sign-ins 50 replies posted

Hello @GKIM ,

The device can operate safely upto a junction temperature of Tj-150degC. But to estimate the junction temperature based on external case temperature, we would also need the total power dissipation information. 

Additionally, the major heat dissipation path would be through the heatsink. Hence, the reliable way of estimating the junction temperature would be using the temperature of the heat sink. Rthja value for the device is provided in the datasheet for two layout conditions. You can consider the Rthja that is applicable for your application based on the footprint used and the Tj can be calculated as below. 

Rth of heatsink(( heatsink datasheet parameter)) - Rthch 

Junction to ambient( PCB) for a given footprint (datasheet value) - Rthja

Tj- Th = Pd( Rthja+Rthch) , where Th - heatsink temperature. 

Can you please let me know if you have the measurement data of the heat sink temperature. Please share us below information to estimate the Pd.

1. Converter topology

2. Input & Output ratings

3. Switching frequency

Regards

Meghana

 

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