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EVAL-AD7634 - Stand-alone mode

Hi everyone!

I wish to use the development kit EVAL-AD7634 as stand-alone mode. According to the datasheet (section "USING THE EVAL-AD762X/AD765X/AD766X/AD767XEDZ AS STAND-ALONE"):

When the CONTROL input to the gate array is LOW, which is pulled down by default, the gate array provides the necessary signals for conversion and buffers the conversion data.

It means that this CONTROL input must LOW when operating as stand-alone, right?

In this post:

http://ez.analog.com/thread/12983,

there is a discussion about how I'm controlling it in serial mode using a DSP. I would like to use the configuration switches from the evaluation kit. So the ADC HW/SW input (pin 25) must be high, correct? When the CONTROL input from the gate array is LOW and the pins MODE[0:1] from ADC are both HIGH, should the pin HW/SW be high? This is not what I'm getting here with the two boards I've acquired.

When I measure the voltage drop between the HW/SW and GND, I get 0V. But when I measure it between HW/SW and OVDD (3.3V), I also get 0V! And when it is between HW/SW and DVDD (5V), it's 1.3V.

Of course, the conversion and transmission aren't working properly.

Can anyone please help me with this?

Thanks in advance,

Gabriel

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  • Hi Alan,

    Yes it is on serial mode. I tried to run it stand alone in bipolar, serial mode with hardware configuration.

    And this what I found:

    The AD7634 should work in 4 ranges, 2 unibipolar and 2 bipolar ranges. This should be configured with pin number 30 and 36 in Hardware conf. mode and with high HW/SW which is pin number 25. This pin 25 in data sheet refer to D14 or HW/SW. It works as input in serial mode which I am working on. In the evaluation board this pin is connected to D12 and there is no control on it, as the last output of D12 is the BD12 which is buffered output from the array.

    In addition, the TEN pin which is pin number 30 is configured through the S16 in evaluation board with switch number 4. Unfortunately this pin is shorted to pin EOC (60) in array which forcing the TEN to be on Low.

    Please find in attachment the shots from the data sheet and the schematic to see the description above clearly.

    So is there any misunderstanding from our side, or there is missing configuration which I should do!

    Thanks for your help,

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  • Hi Alan,

    Yes it is on serial mode. I tried to run it stand alone in bipolar, serial mode with hardware configuration.

    And this what I found:

    The AD7634 should work in 4 ranges, 2 unibipolar and 2 bipolar ranges. This should be configured with pin number 30 and 36 in Hardware conf. mode and with high HW/SW which is pin number 25. This pin 25 in data sheet refer to D14 or HW/SW. It works as input in serial mode which I am working on. In the evaluation board this pin is connected to D12 and there is no control on it, as the last output of D12 is the BD12 which is buffered output from the array.

    In addition, the TEN pin which is pin number 30 is configured through the S16 in evaluation board with switch number 4. Unfortunately this pin is shorted to pin EOC (60) in array which forcing the TEN to be on Low.

    Please find in attachment the shots from the data sheet and the schematic to see the description above clearly.

    So is there any misunderstanding from our side, or there is missing configuration which I should do!

    Thanks for your help,

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