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TPSM84A22: Schematic Verification for power modules of TPSM family

Part Number: TPSM84A22
Other Parts Discussed in Thread: TPSM84424

Hi TI team,

I'm using the following regulators of TPSM family in our upcoming board.

TPSM family:
TPSM84A22: 1.9V@10A
TPSM84A22: 1.5V@10A
TPSM84424: 1.8V@4A
TPSM84424: 3.3V@4A
TPSM84424: 1V@4A
TPSM84424: 1.2V@4A
TPSM84424: 2.5V@4A

Kindly verify the attached schematics for the above circuits.


Thanks and Regards,
Binayak

TPSM_family.pdf

  • Hi Binayak,

    I have received your schematic and am in the process of reviewing it. I plan to provide a schematic review by the end of today.

    Regards,

    Jimmy

  • Hi Binayak,

    The EN/UVLO pin can be left floating since the EN pin has an internal pull-up current source which allows EN to be floating to enable the device. Currently on your schematic, there is only a pullup resistor to "L1_I3V3" for U116 circuit.

    Also for all TPSM84404 (U124/125/128/133 and 135) please make sure you are using the effective output capacitance when calculating the turbo-trans resistor (Rtt). Other than that everything else looks okay.

    Regards,

    Jimmy

  • Hi Jimmy,

    Thanks for the verification. I've some follow-up doubts.

    For TPSM84424, we have used Web Bench software to derive at the circuit values. However while reviewing, I'm finding some differences in what the datasheet and web bench solution.

    (1) For 1V@4A, the Rfbb (in the attached web bench design report) is 14.7K. However, if we look at the datasheet (pg#11), it is 15K for RRT = 124K and Cout = 200 uF. Why is this difference? It is not that 15K is not commercially available. In such cases, should we follow the web bench or the data sheet? 

    (2) This is a generalization of the above question. We use web bench so that it takes care of all the aspects mentioned in datasheet. So, when using the web bench, if the results obtained are in a little variation from the datasheet, do we need to worry?

     

    Thanks and Regards,

    Binayak

    tpsm84424-1V_4A.pdf

  • Hi Binayak,

    Thank you for pointing out this discrepancy. Perhaps the Webench designers were taking into account the 1% variation in resistor value. Using the 14.7k resistor, the calculated output voltage it will result in 1.008V while 15k resistor will result in a 1.000V. In any case if you use either 14.7k or 15k for the bottom resistor, it should satisfy your 1V application. I will contact the Webench team to have them recommend the 15k instead of 14.7k resistor for 1V output application just to keep things consistent between datasheet and webench design.

    Slight variations from the datasheet will not break the device. Always ensure that the device is operating with or as close to the datasheet recommended component values and operating condition.

    Regards,

    Jimmy