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DAC3482 Output issue

HENRY JUNG
Expert 2030 points
Other Parts Discussed in Thread: DAC3482

DEARS.

I am using DAC3482 in one of our boards where am trying to test the DAC in test mode.

There are some unusual need your help.

We are testing with input test pattern in DAC3482.

I : FFFF, Q : FFFF

I : 0000, Q : 0000  is normal.(It is almost no IF output)

But in I : FFFF, Q : 0000, there is very large output signal.

The output signal is larger than 0x7fff.
Our SETUP is used Byte-word, frame sync.

Please refer to the attached Parameter.

*DAC3482 Parameter value

x00  x029C
x01 x000E
x02 x70D2
x03 xF000
x04 x0000
x05 x0000
x06 x3300
x07 xFFFF
x08 x0000
x09 x8000
x0A x0000
x0B x0000
x0C x0400
x0D x0400
x0E x0400
x0F x0400
x10 x3000
x11 x0000
x12 x0000
x13 x0000
x14 x0000
x15 x2000
x16 xE50D
x17 x1435
x18 x280F
x19 x0840
x1A x0020
x1B x0800
x1C x0000
x1D x0000
x1E x1111
x1F x8180
x20 x2400
x22 x1B1F
x23 x07FF
x24 x0000
x25 x7A78
x26 xB6B6
x27 xEAEA
x28 x4545
x29 x1A1A
x2A x1616
x2B xAAAA
x2C xC6C6
x2D x0004
x2E x0000
x2F x0000
x30 x0000
x7F x0000

Thank you

  • 0
    TI__Guru 71809 points

    Hi Henry,

    I see that the 0x02 has setting of x70D2, which indicates the complex mixer + NCO is enabled. Since the complex mixer expects quadrature signal of I and Q, this may be the cause of larger signal when I and Q are not exactly quadrature (it is actually fixed DC at this point).

    When you mention input pattern test, do you mean the pattern checker test described in section 7.3.10 of the datasheet? If so, the input pattern check only check the LVDS bus bit error rate. There will not be an DAC output during the pattern checker test.

    -Kang