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PCA9554: Question about PCA9554

Jimmy Huang
Expert 2965 points
Part Number: PCA9554
Other Parts Discussed in Thread: TCA9555, TCA9536, TCAL6416, TCAL9539

Tool/software:

Hello:

New project - handheld terminal needs, need an expansion chip: need to expand 10 GPIO, 1.8V, the package should be as small as possible,
Question 1: Is PCA9554 suitable? Are there other models recommended?
Question 2: Can these GPIOs be used as interrupts?
Thank you!!!

  • 0
    TI__Mastermind 33583 points

    Hi Jimmy,

    Q1:

    PCA9554 can work, but this device can offer 8-GPIO's which would mean you would need two devices. We don't offer the PCA9554 in QFN or VQFN (although the datasheet shows device info for it), therefore, the smallest package offered for this device is the SSOP 6.20mm x 5.30mm. Total device area would be 6.2mm x 5.3mm x 2 since 2 devices are needed. 

    It might be best to look at the TCA9555, which is the 16-bit version of this IO expander, and has internal 100kohm pull-up resistor, This device is offered in 24-pi WQFN (RTW) package at 4.00 mm x 4.00mm and you will only need 1 device in this design. 

    Our smallest IO expander is the TCA9536 which is a 4-gpio expander but comes in a package sizing of 1.35mm x 0.80mm. In this case you will need 3 devices: 1.35mm x 0.80mm x 3 = 3.24mm. 

    Jimmy Huang said:
    Question 2: Can these GPIOs be used as interrupts?

    A change of voltage on a GPIO pin configured as an input will trigger an interrupt on the /INT pin. The MCU must service this interrupt to see which GPIO changed state. This is how the interrupt functionality works on most of our IO expanders. 

    IO expanders in our TCAL family such as the TCAL9539 and TCAL6416 have interrupt status registers which can be read through the I2C bus to determine which IO flagged an interrupt. 

    Regards, 

    Tyler