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  • TI Thinks Resolved

TPS51116: Correct operation on the case of VTT OFF

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Replies: 1

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Part Number: TPS51116

Hi,
Please advise us this circuit works correctly.

Background:
Since we no longer use the VTT power supply (VTT pin is connected to CTTSNS pin only), we want to turn off the VTT power supply, but the SS pin cannot be pulled down, so the VTT power supply is on.

Current solution
The current circuit is compared with the recommended circuit when VTT is not used in the data sheet.
Could you please let us know whether this process does not cause any problems.

• Connect VTTGND and MODE to GND (Non-tracking discharge mode as shown in Table 3) -> Different
  Connect VTTGND to GND correctly, but connect MODE to VDDQSNS and VLDOIN(1.5V)
• Pull down S3 to GND with 1 kΩ of resistance. -> Different
  Connect S3 to 5V.
• Connect VLDOIN to VDDQSNS.  ->  Same
• Tie VTTSNS to VTT, and remove capacitors from VTT to float. -> Same
• Maintain a 0.033-μF capacitor connected at VTTREF. -> Same

Thanks and best regards,
M,HATTORI

  • Hi Motoyasu, 

    If customer can not follow recommendation on datasheet, I would suggest to keep VTT rail at it is in current design. 

    VTT rail is a LDO, it does not consume power when load current is zero. 

    Thanks

    Qian

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