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ADC1175: ADC1175 different part number

Baris Erdogan
Prodigy 180 points
Part Number: ADC1175
Other Parts Discussed in Thread: ADC1173

Hello,

I have ADC1175 20 mhz, and i could not work properly

Part number is exacly shown below

National Semiconductor VM24ACE3 ADC1175 CIMTC

Although i connected VRTS-VRT each other via 10uf capacitor and VRB-VRBS via 10uf capacitor

I could not get 0.6 V and 2.6 V reference voltages respectivly

But i have National Semiconductor EM36AV ADC1175 CIMTC and works fine

What is the difference between two types of ADC

Thank you

Baris Erdogan

  • 0
    TI__Guru* 91947 points

    Baris,

    There should be no difference. Are you seeing this on two different boards? If so, can you swap the parts to see if the issue is with the board? What are you reading for these two references? Is VCC 5V on this board?

    Regards,

    Jim

  • 0 in reply to jim s
    Prodigy 180 points

    Hi Jim,

    ADC that does not work, has 28.2 mV on VRT and 15.7 mV on VRB,

    the other has 3.07 V on VRT , 1.04 V on VRB

    I already tried what you adviced (swapping parts between eachother) but nothing was changed. Yes Vcc is 5 V

    the adc that does not work is attaching to test converter (TSSOP 24 to DIP 24)

    and i also have ADC1173 and when i attached it to test converter and make Vcc 3.3 V, it does work

    Thank you

    Baris Erdogan

  • 0 in reply to Baris Erdogan
    TI__Guru* 91947 points

    Baris,

    The two parts were manufactured at different times and at different fabs. Both parts should operate per the data sheet. If you think you have a hard failure, you can send us the part for failure analysis. How many of these failed parts do you have? Do all of the failed units have the same markings?

    Regards,

    Jim 

  • 0 in reply to jim s
    Prodigy 180 points

    Jim,

    I have one more failed part and has same markings

    I mean I have two failed parts and both of them have same markings

    What can we do?

    If i send them to you, can you fix the problem?

    Thank you

    Regards

    Baris Erdogan

  • 0 in reply to Baris Erdogan
    TI__Genius 12780 points

    Hi Baris,

    I am looking into the part numbers that you have provided.

    Can you please share a schematic of the board?

    How are you changing from 3.3V to 5V when you go from ADC1173 to ADC1175?

    Do you have enough current for the 5V rail (looks like AVDD/DVDD draw about 17 mA max, but would need some margin to be safe)?

    When you measured Vrt and Vrb, was power and clock applied?

    Best Regards,

    Dan

  • 0 in reply to dBrock
    TI__Genius 12780 points

    Hi Baris,

    I am closing this thread due to inactivity. Please start a new thread if further assistance is required.

    Best Regards,

    Dan