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DAC81416: Inquiry about SYNC Mode Setting and Toggle Function Operation

Kyungsu Kim
Prodigy 10 points
Part Number: DAC81416

Tool/software:

Dear TI Support,

I am a user of the DAC81416, and while basic functions such as voltage output and range settings are working as expected, I am encountering some issues that require assistance.

  1. SYNC Mode Setting: When setting the SYNC mode, I enable the sync bits for channel 0 and channel 1 (bit 1 in the 06h register), and then turn on the DAC power. However, the voltage output does not work simultaneously based on the power-on trigger. When I read the value from the 06h register, the settings appear correct, with the bits for channels 0 and 1 properly set to 1. I have also set the LDAC bit to 1 in the trigger register. To troubleshoot, I also set the LDAC hardware pin to LOW after configuring the sync mode, but no voltage output occurs. The output only activates when I turn the power ON via the power-down register, and the channels are turned on separately. I would appreciate clarification on the expected behavior of the SYNC mode. According to the datasheet, it seems that after setting the power-down register and configuring the sync mode, the output should be triggered via the LDAC hardware pin. Can you explain why it is not working in my case?

  2. Toggle Operation Issue: I have been trying to perform a toggle operation with the following sequence:

    • Range setting
    • Power ON
    • Voltage setting
    • Deactivate toggle register
    • Enable sync mode
    • Set LDAC LOW
    • Set LDAC HIGH
    • Voltage setting
    • Activate toggle register
      After this sequence, I attempt to control toggle pin 0, but no output is generated. I suspect that this issue may be related to the SYNC mode, but I am still verifying this. Any help would be greatly appreciated.
  • 0
    TI__Expert 3380 points

    Hi Kyungsu,

    To understand and debug the issue better,  please provide the exact steps that you have used in your for both the cases - 
    1: Register writes : address + data
    2. Delays between each register writes

    Thanks,
    Sanjay

  • 0 in reply to Sanjay
    Prodigy 10 points

    Dear Sanjay,

    Thank you for your response. Unfortunately, the issue still persists. I have been testing the functionality with the following sequence, and I would greatly appreciate it if you could review it to identify any potential problems:

    1. Set the voltage range.
    2. Read back the voltage range.
    3. Set the voltage output value.
    4. Read back the voltage output value.
    5. Configure SYNC mode.
    6. Read back the SYNC mode settings.
    7. Set LDAC to LOW.
    8. Activate the power mode.

    Despite setting LDAC to LOW, the output does not respond as expected. The output is only enabled after activating the power mode, which makes me suspect that SYNC mode is not being applied properly.

    However, when I read the value of the SYNC mode register (0x06), it shows that the corresponding bits are set correctly. To apply SYNC mode, I send 3 bytes: 0x06, followed by 0x00, 0x01 or 0x02 (for channels 0 and 1), to configure the register.

    Additionally, I have configured the trigger register with both the LDAC and AB toggle pins set to 0. I also tried setting the LDAC bit to 1, but the output still only activates through the power-down register.

    The LDAC hardware pin is functioning correctly, as confirmed through separate testing. To ensure correctness, I have been reading back the register values during testing. While SYNC mode appears to be configured correctly, the output does not operate in SYNC mode.

    For reference, I have also verified that both Broadcast and Toggle modes are disabled.

    Could you please help me identify what might be causing this issue?

    Best regards,
    Kyungsu

    • Additional findings: The sync mode operation was successful. Upon checking, I found that before setting the voltage range and voltage value, I needed to set the sync mode first. Then, after writing to the voltage-related registers and activating the power, I had to activate the LDAC pin to proceed with the synchronization operation. The synchronous mode has been confirmed to work, but the toggle operation is not functioning.

    The current steps for testing the toggle operation are as follows:

    1. Disable toggle mode for all channels
    2. Read the toggle mode register and check the channel status
    3. Set sync mode
    4. Check the sync mode channel status
    5. Set the voltage range
    6. Read the voltage range
    7. Set the voltage to 1V
    8. Activate power
    9. Set LDAC to LOW
    10. Set voltage to 12V
    11. Activate toggle mode
    12. Set CS to LOW and toggle the pin to LOW, then set CS to HIGH, repeating step 12 continuously...

    After setting the voltage and confirming that toggle mode is set, the toggle pin operates, but the output voltage does not change. It remains at 1V and does not change. I need help with this issue.

  • 0 in reply to Kyungsu Kim
    Prodigy 10 points

    Upon checking, I found that the CLR pin wasn't being used separately, but it was operating in LOW. After setting the sync mode, configuring the voltage, triggering the event, setting the voltage, and executing the toggle operation, I confirmed that everything works fine. Thank you!

  • 0 in reply to Kyungsu Kim
    TI__Expert 3380 points

    Hi Kyungsu,

    Let's setup a meeting and discuss the issue in details.
    I have dropped a mail, please check and respond accordingly. 

    Sanjay