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TPS26630-33EVM:   TPS26630-33EVM：TPS26630 Question Regarding NC Pins (Pin 19–24) Connections in EVM

?? ?
Prodigy 30 points
Part Number: TPS26630-33EVM
Other Parts Discussed in Thread: TPS2663

Tool/software:

Hi,

I have a question regarding the TPS26630 datasheet, specifically about pins 19 to 24, which are marked as NC (No Connect).

According to the datasheet, these pins are designated as NC and should not be connected to any signals. However, in the official Evaluation Module (EVM) circuit design, I noticed the following:

Pin 19 is connected to VOUT

Pin 24 is connected to VIN

Pins 20 to 23 are connected to GND

Could you please clarify the purpose of these connections?
Are they necessary for proper operation, or are they implemented purely for PCB layout or thermal considerations?

Thank you for your assistance in clarifying this matter.

  • 0
    Prodigy 30 points

    Hi, 

    In the TPS26630 circuit, the OVP function on PIN 7 is set by a resistor divider consisting of R446 (470 kΩ) and R449 (10 kΩ), which provides a divided voltage of approximately 1.1 V. During testing, it was observed that when R446 is touched by hand, the OVP is falsely triggered, causing the system to reboot. This issue occurs with a relatively high recurrence rate.

    Could you please advise what underlying factors might cause the OVP circuit to be so easily affected and result in false triggering?








  • 0
    TI__Guru** 105721 points

    Hi

    NC pins can be connected to GND or left open or any other potential. 

    On EVM, We connected NC pins near Vin and Vout are connected to Vin and Vout to spread the copper around the Vin and Vout pins. And rest of the NC pins to GND so that the ground plane under the thermal pad can be extended on the top layer. This way it will be more effective in improving the thermal relief to the device than connecting all the pins to Vin.

    Best regards,

    Rakesh

  • 0 in reply to ?? ?
    TI__Guru** 105721 points

    May be the touch is offering some impedance.

    Can you use 100k for R446 and 2.12k for R449 and check the behavior. Lower resistor values offer better immunity to external impedances.

    BR,

    Rakesh

  • 0 in reply to Rakesh
    Prodigy 30 points

    Hi

    I would like to ask if the current circuit design is reasonable. If there are any shortcomings or areas for improvement, please kindly provide your suggestions. Thank you

  • 0 in reply to ?? ?
    TI__Guru** 105721 points

    TPS2663 design looks good.

    Thanks

    Rakesh