Part Number: DAC8760EVM
Other Parts Discussed in Thread: DAC8760, , DAC8750
Tool/software: DAC8760EVM
HI, I'm currently working with a DAC8760EVM. During initial hardware bringup on my bench, the EVM experienced a high-current fault condition. AVDD and AVSS were connected to the power supply through banana connectors and jumper wires. JP1 was disconnected on the PCB. Jumper wires melted almost immediately but the DAC8760 IC didnt get hot. We changed the jumper wires for heavier cabling, power supplies showed zero current consumption and the wires were fine. Here is the wiring diagram of the power supply. AVSS from power supply B and AVDD from power supply A and a common GND.
We connected the USB-DIG-PLATFORM to try controlling the DAC through the software. The software didnt do anything. We tried writing to registers and reading them back but they kept reading the same default values. Sometimes all registers were cleared and then sometimes all registers are filled with 1s? no consistent behaviour. The output voltage was constant at 1.8 volts.
We then thought to try directly with a simple code through SPI. Still the output voltage was not behaving as expected and was almost constant at 1V and sometimes jumping to 2V temporarily. I've checked the voltages on DVDD, VREF and they were as expected: 4.6V and 4.9V respectively.
Next day, we hooked up the same exact setup. I had suspected a short between AVSS and AVDD and while testing for continuity using a multimeter, it picked up a resistance of 500ohms between them and around 600 ohms between AVSS and GND. I hooked up the power supply and enabled internal DVDD but read around 0.5V. VREF also now showed around 1V. The -12V power supply was also drawing up to 600mA. Does this mean that the DAC8750 IC failed short?
I tried the USB-DIG-PLATFORM and disabled internal DVDD but DVDD still read around 0.5V. I traced the DVDD and GND pins on the USB-DIG and measured it directly while the USB-DIG is unplugged. It read 0V. The USB-DIG datasheet mentioned that it could read 5V, 3.3V or Hi-Z but when it is Hi-Z, the I/O should be Hi-Z aswell so I measured the SPI pins and they read 3.3V. Does this mean the USB-DIG is faulty aswell?
Is the DAC8760 bricked and if it is what do you think could cause such failure? Identifying any possible causes is very important as I don't want to brick another EVM in the process and the timeline is tight. Thank you for your time in advance.
