unused pin configured internal pull up pull down

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XiaoPing_Yang
Level 4
Level 4
25 replies posted 10 replies posted 10 questions asked

Hi Sir ,

      In my last discussion , Roy tell me that the unused pins  need not  be configured or be terminated to ground or supply through resistors of typical value of 10K Ohm. My customer now ask if unused pins could be configured internal pull up or pull down , so they can save the pcb space and resistors .

     Thanks.

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I think it is not necessary to configure the unused pin to resistor pull up or pull down,   it is better to let the pin drive mode Analog High Z.

In the previous discussion, Roy gives suggestion that connect 10k resistor to unused pin , aims to avoid the instantaneous noise.

if customer configure the pin to pull up or pull down, it even can increase the damage risk.

As a conclusion, if the customer don't want to let connect the 10k resistor to unused pin, they can let them float, or connect to Ground direct.

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4 Replies
LinglingG_46
Moderator
Moderator
Moderator
500 solutions authored 1000 replies posted 10 questions asked

1:  You should offer us the chip part number.

2: Generally, the pins can direct connect to Ground or floating if unused except the PSoC4000 P1.6.

3: For PSoC4000,the Pin 1.6 can't be connected to Ground if unused.

4: Could you offer us the discussion linker which give the guide that should connect to 10k resistor?

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Hi Linling,

    The PN :CY8C4146AZQ-S423;

    The link : Psoc unused pind tied to GND

    Thanks.

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Hi Lingling ,

     My customer ask  is there any further information ? Is there  some risk that unused pins  be configured internal pull up or pull down ?And 0 or 1 output?

     Thanks.

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I think it is not necessary to configure the unused pin to resistor pull up or pull down,   it is better to let the pin drive mode Analog High Z.

In the previous discussion, Roy gives suggestion that connect 10k resistor to unused pin , aims to avoid the instantaneous noise.

if customer configure the pin to pull up or pull down, it even can increase the damage risk.

As a conclusion, if the customer don't want to let connect the 10k resistor to unused pin, they can let them float, or connect to Ground direct.

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