Other Parts Discussed in Thread: DAC7678, DAC5578
My team is using the DAC7578 12-bit, 8 channel device on a custom board. Prior to the custom board prototype, I have been using the DAC7678 EVM for development. I am experiencing some unexpected issues in the read sequence of the DAC7578. Please see the attached snapshots of the captured I2C byte sequences to the two devices.
DAC7578:
DAC7678:
The test sequence on both devices is:
1. Power up all DAC channels (Power Down Register 0x40; PD1 = PD2 = 0; all channels selected)
2. Write full count to DAC Input register Channel D and update all DAC registers (Global Software LDAC: 0x20; Channel D: 0x03; Full count: 0xFFF)
3. Read back DAC input register D (0x03)
However the read-back from DAC7578 does not reflect the full count written to it, although the voltage on Channel D is observed correctly, at full reference value.
What is the difference between DAC input register and DAC register for each channel?
Which register should be read back in software?
What might be causing the discrepancy in the read back between the two devices?