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TPS544C20: Can we use I2C interface to control TPS544c20 instead of SMBUS

Part Number: TPS544C20

Hi, team

A question from customer, they don't have SMBUS on their board, is it ok to  use I2C interface to control TPS544c20 instead of SMBUS? Thanks!

  • Seems they are not fully compatible, some description of I2C in below link, you can refer to it first, will ask team to double check.

    http://www.ti.com/lit/an/slua890b/slua890b.pdf

    Yuchang

  • Hi, Yuzhao,

    Have you got answer for this? Thanks!

  • Nicole,

    While I2C and SMBus used by PMBus are slightly different, the SMBus physical and transport layer is designed to be compatible with I2C Master and I2C traffic over a shared bus with the following constraints:

    1) The I2C termination voltage should be between 1.8V and 5.5V

    While I2C defines a termination dependent "High" threshold, SMBus defines a fixed "High" threshold that works with I2C traffic for 1.8V, 2.5V, 3.3V, and 5V termination voltages.

    2) The I2C Master should operate between 10kHz and 400kHz

    3) The I2C Master should not generate a CLK low period longer than 25ms

    SMBus uses CLK low > 25ms as a transaction termination / slave reset function which is not part of the I2C spec

    4) The I2C Master should be compatible with optional CLK stretching

    The TPS544C20 does not use clock stretching, but PMBus devices in general use Clock Stretching

    5) The I2C Master must be able to generate Repeated START conditions without a STOP condition.  This is how SMBus devices change the direction of data transfer so that the Master can read data from the Slave device.

    Most I2C Master devices will support these functions and can be used to communicate with PMBus devices, including the TPS544C20.