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TCAL6416: Schematic review of TCAL6416PWR

sharique Ansari
Prodigy 70 points
Part Number: TCAL6416
Other Parts Discussed in Thread: TPS22960, , PCF8574, TCA9554, TCA9554A, TCA9555, PCF8574A, PCA9554A, PCA9555, PCA9554, PCF8575

Tool/software:

Hello,

We have used TPS22960 in our project. We have made schematic as per reference circuit from its datasheet. Can anyone from TI verify this schematic & let us know whether this will work or need some modifications.

  • +1
    TI__Mastermind 34393 points

    Hi Sharique,

    I can comment on the TCAL6416PWR, but not so much the implementation of the TPS22960. For that device you would need to check with the power management teams. 

    TCAL6416PWR

     

     

    Check

    Status (good, bad, okay, ?)

    Comment

    Local Decoupling Capacitors

     Good

    Generally, a 0.1-uF capacitor is placed on VCC, as close to the device as possible

    Verify the schematic pinout matches the data sheet pinout

     Good

     

    Check that the pullup resistors are present on the SDA and SCL net within the schematic.

    Verify

    10k pull-ups are okay but quite weak. What data rate is planned for the TCAL6416? 

    If using the IO expander at 1 MHz, you might consider using stronger pull-ups to decrease rise-time: 4.7k, 2.7k...

    See this application note for more information on choosing the correct pull-up resistor. 

    Unused GPIO pins are biased to either VCC or GND via resistor

     Verify

    Most of TI's IO expander portfolio do not include internal pull-up resistors on the p-port pins; the exceptions are PCF8575, PCF8574, PCF8574A, TCA9555|PCA9555, PCA9554|TCA9554, and TCA9554A|PCA9554A and therefore can be left floating.

    An alternative approach is after powering up the device, any unused p-port pins can be set as an output (does not matter if set high or low).

    TCAL has agile IO features. It has configurable I2C pull-ups internal to the device to keep inputs from floating. This is an additional option. 

    Device address is unique on the bus unless using an I2C switch or I2C MUX to resolve conflicts

     Good

    As far as I can tell, there is only 1 x TCAL6416. If there are multiple, ensure that ADDR is set to make unique addresses, if there are > 2 devices, an I2C switch/mux will be needed for potential addressing conflicts.

    If the device has a /RESET pin, bias the pin high (preferably with a pull-up resistor) after powering up.

     Good

    10k to 3.3V supply

    If the device has a /INT pin and the /INT pin is used, tie this pin to a pull-up resistor.

    Good

    10k to 3.3V supply

    Regards,

    Tyler