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TPS51716

zero lu
Prodigy 20 points
Other Parts Discussed in Thread: TPS51716

TPS51716 was used for notebook intel platform!

Question1

I find the power up time of VTT is very short（about 5us ） from S3 state to S0 state!so it causes big inrush current,A big voltage droop will be happen near to pin2(LDOVIN),The VDDQ will excee specification howIf the source of  pin2(LDOVIN) close to VDDQ POWER Shape for DDR.How to add time   power up time of VTT  from S3 state to S0 state for reducing inrush current!

Question2

How to calculate CAPACITANCE of Cboot?

  • 0
    TI__Prodigy 220 points

    Hi, Zero-san,

    There is no function to extend startup time of VTT. I suggest adding ceramic capacitor close to VLDOIN pin (pin 2) separately from VDDQ output capacitor. The capacitance should be as much as half of total VTT output capacitance or more. PCB trace connecting VDDQ to VLDOIN should be wide and short, and be separated from the trace between VDDQ and VDDQSNS.

    As for capacitance of the boost capacitor, I suggest 0.1uF. Theboost capacitor supplies charge to gate of the high-side MOSFET. The typical gate charge of the high-side MOSFET is about 10nC (at Vgs=5V). When you accept 0.2V drop in boost capacitor at its dischrage, required capacitance is 10nC/0.2V=0.05uF. Therefore 0.1uF is suffcient.

    Best regards,

    S. Ishikawa