hi,
I have a serious problems now on DAC80501.
We are utilizing multiple DAC80501 (16-bit, I2C interface) devices in a Transceiver module, specifically addressing DACs configured for 2.5V output range, such as the TEC set DAC (I2C address 0x48) and Bias set DAC (0x4A).
We have encountered a critical issue where the DAC VOUT is consistently stuck at 0V when the device is supplied with VDD=3.3V. In contrast, a similar DAC (Voltage set, address 0x49) operating at VDD=5V functions perfectly and outputs the expected voltage based on the DAC Data value.
We believe the root cause is the device entering a Reference Alarm (REF-ALARM) state immediately after Power-On Reset (POR), as the default configuration targets a 5.0V Full-Scale Range (FSR) which exceeds the 3.3V supply rail. This REF-ALARM condition clamps VOUT to 0V.
To resolve this, we have implemented an aggressive initialization sequence designed to recover the device and set the GAIN to a safe 2.5V FSR (x1 gain):
1. Software Reset: Write 0x1010 to the TRIGGER Register (0x05) to clear the alarm status and reset the device.
2. GAIN Configuration: Write 0x0000 to the GAIN Register (0x04) to explicitly set the DAC to 2.5V FSR (REF-DIV=0, BUFF-GAIN=0).
3. Timing Delay: Implement a 1ms delay (sufficiently exceeding the required 1 us tUPDATE time) before proceeding.
4. DAC Data Write: Repeatedly write the desired 16-bit output value to the DAC Data Register (0x08), using retry logic.
Observed Result:
Despite our rigorous attempts, including adding readback verification that confirms the GAIN register is successfully set to 0x0000 (or 0x0100 written is rejected for 0x0000), the DAC output for the 0x48 and 0x4A devices remains rigidly at 0V.
Request for Technical Support:
Please let me know what the solution is with i2c commands.