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TPS51100: could you please help explain why TPS51100 just need small output capacitor

Iven Xu
Intellectual 2090 points
Part Number: TPS51100
Other Parts Discussed in Thread: TPS1100

Hi expert,

1, could you please help explain why TPS51100 just need small output capacitor at VTT pin such as 22uF? but the competitor's part -APL5331 need the 470uF output capacitor?

2, my customer is using a LTC3618 switching regulator for with +-3A converter for DDR3 (for 3pcs DDR3), could you please help suggest can we use our TPS51100 to do replacement? or any other suggestion.

Best Regards

Iven Xu

  • 0
    TI__Mastermind 24075 points

    Hi Iven,

    Question 1:

    22uF is the minimum output capacitor to make TPS51100 circuit stable. If customer has load transient requirement, usually more capacitors are needed. In most applciations, we don't need 470uF such a large output capacitor.

    I'm not familar with APL5331, so I can not comment why it needs 470uF output cap. Customer may need to check with ANPEC.

    Question 2:

    TPS51100 is a linear regulator, it can support maximum +/-3A current.

    Due to the thermal convern, we don't recommend to use TPS51100 support 3A contant current.

    For 3pcs of DDR3, the total VTT current should be around 1A, TPS1100 should be able to support it if layout is implemented correctly.

    Please double check with customer how much VTT current is required by 3 pcs DDR3.

    Thanks

    Qian