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# UC2845A: Absolute Maximum Operating temperature for UC2845A

Part Number: UC2845A

I need the Absolute Maximum Operating Temperature for UC2845AD8.  Device is rated to 85C ambient but our environments often exceed this.

If Absolute Maximum Operating Temperature is not available, then can someone provide the maximum power dissipation allowed at 85C ambient.

From there i can calculate a junction temperature

• Hello Kerry,

The ABS MAX rating of the UC2845A is 150 degC.  However, we do not recommend operating continuously at ABS MAX condition.

If we look at the Electrical Characteristics Table in the datasheet (see part of datasheet below) we see the UC2845A is tested up to TA=85 degC, UC2845AQ is tested up to TA=125 degC, and TA=TJ.  The "TA=TJ" is standard in the industry.  It means the part is dissipating very little power during electrical test and TA=TJ is a safe assumption.   The entire family (A, AQ, etc) are derived from the same design, die, and process.  Therefore it's safe to use TJ_max = 125 degC for the A version.

Regards,

Eric

• Hello Kerry,

The A and AQ parts are derived from the same design, die, and process.  The AQ supports TJ_max = 125 degC so the A version will support TJ_max = 125 degC too.

Eric

• is functional operation guaranteed at 125C or is this a stress limit?

• Hi Kerry,

Only the AQ version is tested and guaranteed to TJ=125 degC.  If you want to be 101% sure of the functionality at 125 degC then you must switch from the "A" version to the "AQ" version.

Eric

• ok, thanks ...  reason I'm being picky is I'm inputting data into a database and it has to be correct. and reflects TI document spra953C for Absolute Maximum Operating Temperature, versus the Absolute Maximum Junction Temperature (often Tjmax) which doesn't guarantee operation to that temperature.  So when we run into 85C ambient parts we have to dig to see what they can really do.  I will pass this on to our components experts to get their take.

• OK.  Thanks for the explanation.  Not being picky, just thorough.

Regards,

Eric