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TPS65911: TPS659118 Unused Pins

Debora
Intellectual 645 points
Part Number: TPS65911
Other Parts Discussed in Thread: 66AK2G02,

I am doing a 66AK2G02 design based on the EVM2KG. Do you have guidance on what to do with unused pins or unused functions of the TPS659118?

For example, in the EVM2KG, there are pairs of capacitors on the inputs and outputs of regulators that are not actually connected to anything in the circuit:  VCC7/VRTC, VCC4/LDO5, VCC3/LDO6-8. Are all these capacitors really required?

I infer that nothing needs to be connected to VBACKUP, because the EVM has only a jumper there and ships with nothing installed on the jumper.

Regards,

Debora

  • 0
    Intellectual 645 points
    By the way, we do not need VIO either. Any guidance on how to correctly leave it unused?
  • 0 in reply to Debora
    TI__Genius 17380 points
    Hi Debora,

    Our expert is out until Monday, but I believe they will be required for all rails which are enabled as part of this OTP's sequence. Not connecting capacitors could lead to instability and a power fault could be detected. The schematic checklist on the TPS65911 product folder shows what to do with Not Used Features, but I believe it is referring to rails which are not enabled by default in the OTP.
  • 0
    TI__Genius 10000 points

    Debora,

    As Kevin suggested, you can use the schematic checklist (http://www.ti.com/product/TPS65911/technicaldocuments) in order to best determine how to deal with unused pins.

    Most pins can be grounded, and in doing so, will not need the capacitor. However, some pins are critical to the internal functions of the device, and the schematic checklist provides the best way to handle those pins. VRTC and VIO must be handled correctly for reliable performance of the device. 

    Additionally, in order to ensure a more reliable signal, it is recommended that VCCIO and FB pins be grounded, rather than left floating. 

    Lastly, if you do not need VBACKUP to keep the device powered if the main power is lost, you can tie this pin to GND or VCC7 (in the schematic checklist).

    Please let me know if you have any further questions!

    Thanks,

    Nastasha

  • 0 in reply to Nastasha
    Intellectual 645 points
    Thanks!

    I'm still a little confused. Assuming I use the OTP sequence, Nastasha, can you confirm what Kevin said that I need to use capacitors on unused rails rather than connecting them as in the schematic checklist?

    Regards,
    Debora
  • 0 in reply to Debora
    TI__Genius 10000 points

    Debora,

    I can confirm for this device that you do not need the capacitors and you can follow the schematic checklist. We apologize for the confusion!

    Thanks,

    Nastasha