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TL2844B: Regarding maximum power dissipation of PWM controller

Archana Rao
Intellectual 915 points
Part Number: TL2844B

Hi,

We are planning to replace UC2844ADM (from Microsemi) with TL2844BD-8 (got this from TI crossreference search) in one of our projects.

I would like to know the maximum power dissipation at ambient temperature of 25 deg C for TL2844BD-8.

The datasheet provides a formula to calculate based on thermal resistance, TJ and TA, but does not provide any information related to max power dissipation either in operating or absolute maximum ratings.

Can you please let me know TL2844BD-8 maximum power dissipation?  Is it 1W max?

Also, can you please let me know the part life cycle status in terms of number of years for TL2844BD-8?  I know that this product is active, but wanted to know the duration.

Awaiting for your reply.

Regards,

Archana Rao

  • 0
    TI__Guru* 86166 points

    Hello Archana,

    This has to do with the ambient temperature of the design and the maximum junction temperature device and the device’s thermal impedance theta JA (Rja) and the ambient temperature you are using.

    The 8 pin D package has an Rja of 97 deg. C/W and a maximum junction temperature of 150 C. At 80 degree C ambient the maximum power would be 720 mW.

    Tjmax = Tamb +Pmax*Rja

    Pmax = (Tjmax-Tamb)/Rja = (150-80)/97 = 720 mW

    Regards,

    Mike

  • 0 in reply to Mike O'
    Intellectual 915 points

    Hi Mike,

    Thank you for your reply.

    The information provided was very helpful.  Can I consider that at -40deg C, the device can handle up to 1.96W of power dissipation assuming that max junction temperature  is 150 degC?

    Regards,

    Archana Rao

  • 0 in reply to Archana Rao
    TI__Guru* 86166 points

    Hello Archana,

    Your calculation is correct.  I might reduce the 150 degree C to 125 degree C in your calculation for design margin.

    This would put the absolute maximum at -40 C at 1.7W.

    Regards,

    Mike