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Original question:

DAC3171 configuration problem

DAC3171: DAC3171

EngineeX
Prodigy 30 points
Part Number: DAC3171

Hi， 

I’m using DAC3171 in 7-bit mode，but finding that the lower 7 bits seems not showed because the noise floor is much higher. I think DAC3171 does not work in the 7-bit mode properly.

and I have found that the Bit 6 of config5 is always 1，the problem is that if Bit 6 of config5 is 1, the Bit 5 of config5  also should be 1 according to Table 12 in  datasheet of DAC3171，but actually it's 0.

check the da_clk input to pin6 and pin7， the clock is OK.

I suppose that my power up sequence is not right。

should I provide the DACCLK and DA_CLK to the DAC3171 first，then config the DAC3171 register ?

The dac3171 register configuration is as follow:

0x00  0x6EC
0x01  0x401E
0x02  0x3F80
0x03  0x1C71
0x08  0x6000
0x09  0x8000
0x0A  0xF080
0x14  0x0000
0x01  0x401E
0x01  0x403E
0x01  0x401E

This problem has confused me for three days, pls give me some advice.

I'm looking forward for your reply,thanks a lot.

  • 0
    Prodigy 30 points

    Add:

    when I read the config5 register, it turn out to be 0x1F40, means ‭0001 1111 0100 0000‬，

    there are  alarms in Bit6 and in Bit[13:11].

    this register 5 should be 0x0000 if DAC3171 works normally.

  • 0
    Prodigy 30 points

    Hi, 

    I have checked my power up sequence, which is as follow:

    1. set TXENABLE to 0;

    2.supply all 1.8V AND 3.3V;

    3. provide DACCLKP/N,DA_CLKP/N, DA[6:0]P/N

    4.Toggle the RESETB pin for 25ns minimum

    5.Program the SIF registers

    6.set TXENABLE to 1.

    The power sequence is exactly as same as the Power-up sequence in page 38 in the datasheet of DAC3171.

    we also bypass the FIFO to check this problem by setting bit 7 to 0 in config0，but it doesn't make any difference.

    It seems that the FIFO buffer is OK.

    could you  help me to solve this problem please?

  • 0 in reply to EngineeX
    TI__Genius 10655 points

    Hi EngineeX,

    I have notified the DAC3171 expert regarding your question.
    He will provide a more detailed response soon.

    Regards,
    Vijay