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AMC7812 issue about address sequence

Longchang Chen
Intellectual 1350 points
Other Parts Discussed in Thread: AMC7812

There is 2V voltage at AMC7812 DAC output pin in power on , but after power on, when DAC have output, then it  is ok.  does this 2 V voltage at power on can damage AMC7812 pin? another, customer connect A0/A1/A2 to 001, the address should be 0x62, but customer can't operate with 0x62, when read and write AMC7812 with 0x2C address, it is ok, 0x2c should be 100(A0/A1/A2),  does there is wrong description about A0,A1,A2 in D/S, should be A2,A1,A0. 

many thanks 

  • 0
    TI__Genius 11750 points

    Howdy Chen Longchang,

    Regarding the DAC output 2V voltage.  

    • Is this voltage generated by another IC connected to the DAC output? Is it a weak pull-up, high impedance?
      • My main concern is that the 2V will source or sink current from the DAC output.
    • The Address bit selection is described in the datasheet, page 49 to be exact.  The chart is provided below for reference.
      •  The master sends the 7-bit AMC7812 slave address followed by either a '1' or '0' (direction bit).  Read operations are set to '1', while write operations set the bit to '0'.  This information is located on pg 53 of the DS.
    • Please note that for the following A0/A1/A2 to 001,  a write would be '0x58' and a read '0x59'
    • When A0/A1/A2 is 100, a write would be '0xC4', and a read '0xC5'

    Best Regards,

    Matt

  • 0
    Prodigy 10 points

    Hi Longchang,

        As for the A0/A1/A2 address, i think your customer using 0x2C and it works, that may be caused that the API he is using only take 7-bit address (according to the table, it's 0101100=0x2C), and other API cares about R/W bit, in other words, if he passes 0x2C and calls R, the driver will form: 7bit+R. If that's the case, that result is as expected.

    regards