DAC712: DAC712U output voltage

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Replies: 3

Views: 53

Part Number: DAC712

dear  

 1.   DAC712U has been used for more than 10 years in my customer device,recently, my customer purchase 240pcs DAC712U,   test 12pcs,   1pcs  DAC712 Fail

      iI is normal while DAC712u work ten minutes before, but afer ten minutes , output  voltage deviation more than %0.4

 2.   Shutdown power ,restart the device , but it is keeping output  voltage deviation more than %0.4

 3.    cross-over experiment, details data show as below

DAC712u test data

 num

test item

1# ok

2# NG

1#(change2#的NG DAC712u)

2#(change1#OK DAC712u)

1

Vcc

15.04V

15.05V

15.04V

15.05V

-14.98V

-14.98V

-14.98V

-14.98V

2

V ref

10.22V

10.17V

10.22V

10.17V

3

V in

-32088(-9.793V)

-32088(-9.793V)

-32088(-9.793V)

-32088(-9.793V)

4

V out

-9.793V

-9.839V

-9.844V

-9.789V

1#ok is qualified board and 2#NG is defective board

from test data,we can see that the output  voltage deviation phenomenon follow DAC712U   any advice?thanks in advance~

3 Replies

  • Hi,

    0.4% error is not acceptable for DAC712U. Total unadjusted error for the device is approx. +/- 20mV ( includes INL, DNL and Gain error).

    I am curious to note the measurements for the Vref . Min and Max for reference  voltage is 9.975 to 10.025V, where as in your case you are measuring higher voltages. How are you measuring these voltages? Is this measurement done with precision multimeters?

    Please note that the LSB size of the device 305uV assuming a 10V reference and +/-10V output range.

    So for a code of -32088 should produce ideally -9.786V +/- 20mV ( Assuming offset error is nullified).

    Regards,

    AK

  • In reply to Akhilesh K:

    Direct test voltage on pin5, using Agilent 34401A precision meter measurement.

    What is the reason for the reference voltage of 10.17v and 10.22v?

    After testing the A-B-A Switching IC, we find that the problem follows the IC. Are the parameters of the new IC different from those of the old one?

    10.17V

  • In reply to HY yang:

    Hi,

    This reference voltage looks interesting.

    Need to check with production team for any change in test program revision or limits change, Vref of 10.17 is clearly outside the limits of the specification.

    I am assuming you are using a calibrated meter. Also can you please check the reference voltage by disconnecting the trim pots from the Vref?

    I just want to isolate the reference voltage alone.

    Regards,

    AK