Hi, I am working with a legacy circuit in which the AD5390's DCEN/AD1 input was not tied either high or low. The design was suppose to operate in standalone mode for an SPI bus. Is there any guarantee that the AD5390 will operate in SPI standalone mode?
The DCEN/AD1 is an input pin so we don't recommend it to be left floating. Since you are using SPI transmission, the pin functions as the DCEN, you might encounter problems when you are trying to readback from the registers.
Hi Rainier, thank you for the reply. What about for writing, would you expect issues writing to registers?
Thanks and regards,
You might still have problems during a write sequence if the DCEN is accidentally high. If there are cases wherein you might have added some clock signals the data will ripple out of the shift register and would appear on the SDO line.
So we are recommending all input pins like the DCEN/AD1 to be at known states at all times.