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# ISO7762-Q1: Maximum operating junction temperature Tj

Part Number: ISO7762-Q1

Team,

the datasheet states the abs max value for junction temperature Tj as well as the maximum operating ambient temperature.

What is the maximum operating junction temperature for this device?

Thanks

• Hello franziskus,

The Absolute Maximum Ratings listed out in table 7.1 list the conditions that must not be exceeded for device reliability. Whereas operating junction temperature depends on the ambient temperature and power dissipation of the device and can be calculated for your application using the equation below.

The power can be calculated by using the current and supply voltage from the Supply Current Characteristics table that corresponds to your application.

I hope this helps.

Best,
Andrew

• Thanks for the detailed answer Andrew! I understand that, using this formula, I can calculate the actual junction temperature that my device is currently at.

My question aimed at the maximum allowed value of that Tj during operation.

This would be in contrast to the abs max Tj value that specifies the maximum Tj before device is potentially damaged.

Thanks

• Adding to my first reply and coming back to your initial reply and the screenshot, I guess that Tj(max) = Ts = 150C is the maximum allowed junction temperature.

Can you confirm that Tj=150C is the maximum allowed operating junction temperature?

• Yes, the device will operate according to the datasheet as long as it remains below the maximum junction temperature of 150C. Therefore, 150C is the maximum temperature the device is guaranteed to operate at without damage (either immediate or over time). Since the device temperature is dependent on environmental conditions and the device inputs, there is no specific operating junction temperature.

Best,
Andrew

• Hi Franziskus,

I would like to add some inputs to what Andrew has already shared to further clarify and address your question.

Recommended operating conditions are defined only for those parameters that can be controlled or applied to the device directly by the user. e.g., supply voltage to VCC, signal voltage to INx pins, datarate to INx, ambient temperature, etc. All these parameters parameters have recommended operating ranges and some of them also have absolute maximum ratings beyond which device could get damaged.

While the junction temperature is not a parameter that can directly be applied externally rather it can only be calculated based on other test conditions. Hence, junction temperature only has absolute maximum range defined. Even during device operation, this is the same range that a user should refer and limit the device use such that junction temperature doesn't exceed absolute maximum limit.

Hope this helps with the clarification that you were looking for. Let us know if you have any further questions, thanks.

Regards,
Koteshwar Rao

• Thank you very much for your detailed explanations Andrew and Koteshwar. This helps a lot!