• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 33 subscribers
  • Views 131 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PCA9555: PCA9555DBR default state and Pull up

Sooraj Surendran
Prodigy 110 points
Part Number: PCA9555
Other Parts Discussed in Thread: TCAL6416

Tool/software:

Hello Team 

Am using an PCA9555DBR Port expander and configuring P00 to P07 as Output and P10 to P17 as Input. So here do i need to keep pull up resistor ? and would like to know what is the default state of Port expander output pins? it will be high or low or same as pull up resistor value. Can u please suggest on this. 

  • +1
    TI__Guru 53958 points

    Hi Sooraj,

    Sooraj Surendran said:
    So here do i need to keep pull up resistor ?

    The internal 100k PU resistors cannot be disabled within the PCA9555. 

    Consider switching to a device like TCAL6416 which would allow for programmable PU/PD resistor selections on individual I/O pins. 

    If you want a p2p compatible version of the PCA9555DBR without PU resistors, consider TCA9535DBR. 

    Default state of the PCA9555 is all I/O's configured to high-impedance CMOS inputs with 100k PU resistors attached to each individual I/O. 

    PU resistors are only required if you know that some I/O's will be left floating. 

    Regards,

    Tyler