AB-in / CD-out limited to 24-bit?
I'm building a circuit using the ADAU 1701 on the A/D development board for that chip, and am using an "ABCD" module. I was hoping that, once I was in the digital domain, I might use some of the headroom afforded by the 28-bit internal architecture, and so I scaled my values within the circuit higher than a value of "1," figuring that there are four more bits to play with before topping-out. Other modules seem to be quite happy at these elevated levels, but the ABCD module isn't. If I apply a level in excess of "1" to the C or D inputs, what I get out seems to bounce around and change sign, as read with a Readback module on the output. Is this the case, and what other modules might have a similar headroom issue?
Hello Jim,
I'm having trouble duplicating this issue -- Running the ABCD_Comp with signals ranging from -16 to +16 [actually that's (+16 - 1 LSB)] at any input, it performs as expected:
Perhaps you could attach a sample project which exhibits the undesired effects.
Best regards,
Bob
Thanks for looking, KJBob. Not sure what was going on, but next time I booted the system it was gone. Very strange, reminded me of old analog days and violating the signal limits of a CMOS switch... where the substrate or whatever gets jerked around by an analog input that's too large and appears on other sections of the chip. I have tried to repeat the problem also, but things are working as they should now. Thanks again.
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EZ Admin
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