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TPS51916: Device output capacitor between VTT and GND

Joe Ji
Intellectual 2085 points
Part Number: TPS51916
Other Parts Discussed in Thread: TPS51216,

Hi team

There is one question related to our legacy device TPS51926A.

The background is customer has some stock of our old device and need to use up them, so they use TPS51926A in the same circuit with TPS51216.

The VTT output capacitor of TPS51916A is 3*22uF, the same capacitor of TPS51216 is only 10uF. In my opinion, the capacitors configuration difference is due to the output current spec, is there any other reasons for the difference between 2 devices output capacitors? 

If TPS51916A applied in the same circuit as TPS51216, the maximum LDO output current keep 2A, should I change the VTT capacitor to 3*22uF or just keep it to 10uF?

One more question: Are TPS51916 and TPS51216 the Bom to Bom devices?

P010052900_TPS51916A_DS.pdf

in case you can't find the legacy device datasheet, I attach it to the post.

Thank you

Best regards

Joe

JUL 21

  • +1
    TI__Genius 10662 points

    Hi Joe,

    Ideally you would start with the recommended capacitance and then depending on the transient change that you would expect or the current needed, you would add more capacitance. On page 20 of the datasheet for the TPS51916, it states 3x22uF (or larger) ceramic capacitor(s) need to be connected close to the VTT terminal for stable operation. The same can be seen on page 19 of the datasheet for the TPS51216 but for 10uF. Due to this I would recommending changing to the 3x22uF. You could try extensive testing with 10uF and check for stability or other issues, and then design based on your findings, but TI recommends 3x22uF, and without this then normal device operation might not be seen.

    Joe Ji said:
    One more question: Are TPS51916 and TPS51216 the Bom to Bom devices?

    These two devices should be pin to pin change capable yes. They are both 2.9/3.1-2.9/3.1 in size as well thus they should take the same amount of space up. However due to these extra capacitors needed then the total amount of space may end up increasing or need to change, but there may be already existing room to add these spaces to the design. 

    Thanks,
    Field