Hi everyone,
we have designed a custom board using four DAC81404 which are connected in a daisy chain.
The digital supply is at 5V, the analog supply at +/-14V.
The #RESET and #CLEAR pins are pulled up to DVDD, the #LDAC pins are pulled down to GND.
The SENSEn pins are unconnected, the SENSEp pins are connected to the outputs with 470pF capacitors between output and CCOMP.
The design aims to use the internal reference, so no external reference is connected to VREF.
For configuration I send the following commands:
1) 0x030004 => set SDO-EN bit in SPICONFIG register for daisy chain. (Is this actually necessary, since the reset value of the bit is already 1 ? )
2) 0x040000 => activate internal reference
3) 0x090000 => deactivate power-down
In the oscilloscope screenshot, the signal DC01 is the daisy-chained data from first DAC to second, DC12 from second DAC to third and DC23 from third DAC to fourth (last) in chain.
When i check the VREF with a DMM, I can see that the 2.5V appear after those commands are sent.
Sadly, on my custom board I have no MISO, so no means to read back e.g. DEVICEID register for testing.
Afterwards, I write some values to the DACn registers.
But the DAC outputs all measure 0 Volt.
Any ideas for further troubleshooting? Any help is much appreciated.
Kind Regards,
Marcel
