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TPS54294

shekhar SAINI97194
Intellectual 550 points
Other Parts Discussed in Thread: TPS54294, SWITCHERPRO, TPS54291

Hello,

We are using TPS54294 in our design, we are surprised why datasheet does not talk about line and load regulation over temperature ( -40 to 85C). This IC has Pseudo osc inside it, what does it mean. I tdoes not talk about power dissipation. 

We think this device is not meant for industrial application but why TI specify it as industrial grade.

Please help as we have to change the whole design.

 

  • 0
    TI__Guru**** 191445 points

    The TPS54294 has the VFB feedback voltage specified at room temperature, but the temperature coefficient is given in the next line.  That is the parameter generally responsible for regulation performance.  I have found in most applications the line and load regulation does not vary much with temperature.  The TPS54294 is generally targeted for consumer applications, but it is used across many application types.  These parts use DCAP2 control.  There is no internal oscillator.  It uses adaptive on time control and hysteretic off time control.  the internal adaptive on time controller is designed so that the perceived switching frequency remains fairly constant over line and load conditions.  It is difficult to calculate power dissipation as it is not possible to measure the switching characteristics of the internal switching FETs.  In general, these devices are designed so that they will operate with junction temperatures less than 150 C on well designed printed circuit boards for ambient temperatures below 85 C.  I recommend you use the TI provided software (usually Webench, but in this case Switcherpro) to estimate the power dissipation for your application.

    If you have specific concerns about regulation or have data that indicates the performance is not as you expect, please post it for review.

  • 0 in reply to JohnTucker
    Intellectual 550 points

    Hello John,

    Thanks a lot for your answer.

    We were using it for industrial application but as you said it is meant for consumer application.so we have replaced this part with TPS54291. TPS54291 seems to be better solution for industrial application.

    What would you say about the TPS54291 part?

    Note: we can't change the package as we are in layout stage of the board.

    Regards

    Shekhar

  • 0 in reply to shekhar SAINI97194
    TI__Guru**** 191445 points

    The TPS54291 has a slightly lower operating temperature range.  Since the typical over temperature protection is at 145 C., the recommended operating junction temp is limited to 125 C.  Other wise, the temperature rating should be the same.  TPA54291 uses a completely different architecture than TPS54294 (current mode control vs. DCAP2).  TPS54294 is 2A/2A and TPS54291 is 1.5A/2.5A.  DCAP2 is much easier to design and can get fast transient response with low output capacitance.  For Current mode control, you may need additional output capacitance and you will have to design the external compensation.  You do get true fixed frequency operation with TPS54291.  If you are comfortable with designing in current mode control and understand the trade-offs between the two devices, then I do not have any issue with your choice.