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ADC0838-N

Angela Qiu
Prodigy 240 points
Other Parts Discussed in Thread: ADC0838-N, TMS320C6745, ADC088S022

Hello

I want to connect to ADC0838-N with TMS320C6745,  I don't want to use level change IC, In my opinion, I want to let the output of DSP connect to ADC0838 directly, and let the output of ADC0838 as 2.4V as the figure from datasheet ,but  how can I  do?

thanks

 

  • 0
    TI__Intellectual 2630 points

    Angela, In regards to the ADC0838 2.4V Vout high level (logic = 1) min looking at the TMS320C6745 datasheet it's recomended operating condition for Vin high level min is 2V. And 2.4V > 2V. So the two devices are in compliance.

  • 0 in reply to Jason Seitz
    Prodigy 240 points

    Hello Jason

    Thanks for reply.

    I still have some questions,

    ADC0838 is 5V power supply, so the high level "1" should be 5V ( of course, if Vcc=4.75V, the min level can be 4.5V), but how can I let the "1" as 2.4V?  I want to know the method.

    Thanks so much.

    Angela

  • 0 in reply to Angela Qiu
    TI__Intellectual 2630 points

    Angela, After reading your latest question it seems that you want to ensure that your logic "1" is 2.4V. You can do this by increasing the load at data out (DO) pin. As Iout increases (i.e. as the load increases) it will be harder for the ADC to pull the output up to VCC. At Iout = -360uA the min output is 2.4V, increase Iout further and min output will drop even lower. This current is set with the load resistor (Rl) to ground.

  • 0 in reply to Jason Seitz
    Prodigy 240 points

    Hello Jason

    Thanks for reply.

    Due to the min SPI clk of 6745 is 590K and the max SPI clk of ADC0838-N is 400K, we had to give up ADC0838-N and change the ADC IC as ADC088S022.

    But  still thanks anyway.

    Angela