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PCA9544A: native SMBus support

Bart
Expert 6460 points
Part Number: PCA9544A

Team,

are working with battery packs which support SMBus.

Is the PCA9544A supported by native SMBus from Windows?

Can PCA9544A allow Windows to handle all the batteries on the bus without additional MCU on the PCB? 

We would like that the data from all batteries are accessible in Windows without any extra logic used on the PCB.

Thanks for your feedback.

  • 0
    TI__Guru 73331 points

    Hey Bart,

    "Is the PCA9544A supported by native SMBus from Windows?"

    The PCA9544A was a device that was designed for an I2C bus. With that said, the SMbus is a subset of I2C. The main difference I notice is the ViL and ViH in the SMbus standard are a static voltage at 0.8V and 1.35V respectively. (version 3.1 of the standard)

    VoL for SMbus is still 0.4V (at 4mA and 6mA for 100kHz and 400kHz). As long as our device sees a VoL lower than ViL from I2C standard and a VoH (this should be provided by a pull up resistor so it isn't a concern) that is atleast 70% of Vcc then our device will work on the SMbus.

    --------------

    I don't see any problems with using this device on a SMbus though its ViL and ViH do not match with SMbus's standard.

    Thanks,

    -Bobby

  • 0 in reply to BOBBY
    TI__Expert 6460 points
    Hi Bobby,

    thank you. Regarding voltage levels, there shouldn't be any problems.

    I am wondering if Windows can access data from all batteries on the PCA chip, without using any additional MCU or controller?
    So, that means, plugging PCA9544A directly to the motherboard and accessing data from all batteries on the other side of PCA9544A.

    Is that possible?

    Thanks & regards
  • 0 in reply to Bart
    TI__Guru 73331 points

    Hey Bart,

    This is an I2C switch, as long as you write to the internal registers on which channels you want enabled then you can avoid address conflicts. The answer is yes, if you can directly talk to the device. You can find instructions in section 9 of the datasheet.

    Thanks,

    -Bobby