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DAC121C085 - I2C Addresses

Rene Hegewald
Prodigy 10 points
Other Parts Discussed in Thread: DAC121C085

Hello,

the revised datasheet of the DAC121C085 (Revision E from January 2016) specifies two different I2C addresses for each possible address coding (table 1). Our observation is that only the first of these addresses works. If we use the second one (we tried 46h and 47h for devices that are accessible by address 4Ch and 0Eh) the DAC121C085 does not acknowledge the address byte but holds the SDA line low after the acknowledge bit and avoids further communication on the I2C bus until the next power cycle.

So what is the meaning of the second I2C address in table 1 of the datasheet?

Thank you and Best Regards,

Rene

DAC121C085

  • 0
    TI__Genius 16890 points

    Hi Rene,

    We have seen the problem in the past that the DAC will respond to two different I2C addresses.  For example, if the DAC121C085 was being used with an address of 0001100 and there was another device on the I2C bus with an address of 1000110, when the master wrote to the device with an address of 1000110 the DAC would try to use the data that had been sent. 

    A better description for the Slave Address column in Table 1 would be that you should use the first address listed and make sure that there is not another I2C device on the bus with the second address.

    We will need to update the datasheet.

    Thanks,

    Mike

  • 0 in reply to Michael Stout
    Intellectual 670 points
    Thanks Rene for pointing this out and Mike for the clarification. I was just about to ask the same question for the DAC081 and DAC101 which also has two addresses in Table 1.

    Looking forward to the updated data sheets for the I2C DAC family ;)

    Thanks, Ken