AD5232 Daisy Cain Mode Issues

Question I am using 7 x AD5232 in Daisy Chain mode. The timing is not in the correct order. Are there any known problems in this configuration? Answer There are no known issues with the AD5232 in daisy chain mode. The SDO line and SCLK lines are gated by the /CS line. Data is latched from the serial shift register into the address decode logic on the rising edge of /CS. To daisy chain multiple AD523X devices, simply connect SDO to SDI and run a common SCLK and /CS to all devices. To program many AD5302s in a "daisy chain" configuration, pull the /CS lines low on all chips. Send the data into the CLK and SDI pins of the first AD523X in the chain. The data format should be data for the last potentiometer in the chain sent first. Once data for all converters in the chain is sent, a positive edge on /CS will load data into all potentiometers simultaneously. You must always write the same word length to the chain of devices. For example when two AD5232s are daisy chained together, you must always write 32 bits, for 4 devices, you must write 64 bits. If you only want to update the contents of a single device, simply write a NOP to the device locations you do not wish to update. Also ensure that the recommended 2k pull-up resistor is used on SDO. The most likely cause of a failure is in the digital interface.

ad5232: Connection of VSS

Question Can Vss left floating? Answer You need to either ground Vss or bias it negatively at any time, Vss cannot be floating. The potentiometer can still be written with new values but EEMEM cannot be programmed when Vss is floating. According to the designer of the part, the AD5232 has two grounds; DGND and Vss. DGND acts as a reference point for the digital pads only. The rest of the digital logic, including the EEPROM along with the RDACS are powered between Vdd and Vss.

Question We're designing a audio interface and there raised a question about the daisy chain configuration. In the datasheet is written that the SPI controller has to send a data package containing two 16bit data fields. Thats understandable, but what if we try to read from the an5232? Can we expect a 32bit package from the an5232? And will this package leave the last chip in the daisy chain trhough it's SDO? Answer To daisy chain multiple AD523X devices, simply connect SDO to SDI and run a common SCLK and /CS to all devices. To program many AD5235s in a "daisy chain" configuration : Pull the /CS lines low on all chips. Send the data into the CLK and SDI pins of the first AD523X in the chain. The data format should be data for the last potentiometer in the chain sent first. Once data for all converters in the chain is sent, a positive edge on /CS will load data into all potentiometers simultaneously. You must always write the same word length to the chain of devices. For example when two AD5235s are daisy chained together, you must always write 32 bits, for 4 devices, you must write 64 bits. If you only want to update the contents of a single device, simply write a NOP to the device locations you do not wish to update. Also ensure that the recommended 2k pullup resistor is used on SDO !