What is the range of the Vref on the external Vref pin?
We would specifically need to apply 0.5V.
Register 0x18 is a digital scaling of the output codes. It does not adjust the analog internal reference, but it will scale the output codes so that a smaller input amplitude will result in a full-scale output.
It sounds like this could work for you. For example, if you need a 1Vpp differential signal to produce a full scale output, Register 0x18 will do this for you. This is still with analog VREF = 1V.
Will this fulfill your requirement?
Thank you for your interest in the AD9608.
VREF on AD9608 must be 1V. What is the reason for wanting to apply 0.5V to VREF? Do you want to adjust the full scale voltage of the ADC, or is 0.5V a voltage you have readily available in your system?
Doug, thanks for your reply. The main reason is: this ADC replaces an other one from a different company, and the firmware in the FPGA shall be identical. So it makes it required, to have 0.5V reference to have the same input voltage range. So at the end it required, to change the input voltage full scale range.
What happens, when using 0.5V external reference? I notices, that the datasheet tells in table 18, register 0x18:
It would allow to adjust the Input voltage between 1Vpp and 2Vpp.
Does it mean, it adjust the internal reference between 1V and 2V ?
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