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DAC43401-Q1: How does DAC OUTPUT change gradually?

Hyejin Joo
Prodigy 15 points
Part Number: DAC43401-Q1

Depending on the situation, I'm changing DAC Output level from 5.1V to 2.5V, and vice versa.

How can I change this DAC Output level gradually?

As-is: Please refer to only blue wave.

To-be:

  • +1
    TI__Mastermind 25443 points

    Hello,

    You can set the slew rate in the GENERAL_CONFIG Register:

    Set the high and low data values in the DAC_MARGIN_HIGH and DAC_MARGIN_LOW Registers:

    Then you can slew between the high and low values using the external GPI trigger or the software trigger in the PMBUS_OPERATION Register:

    Best,

    Katlynne Jones

  • 0 in reply to Katlynne Jones
    Prodigy 11 points

    Hello, I'm a co-worker with her. 

    First of all, I'm wondering if pmbus bit is right as mentioned in the datasheet.

    I run like this

    Reg: 0xD1, Val: 0x1204  // PMBus enable, slew rate 25us 

    Reg: 0x25, Val: 0x0960

    Reg: 0x26, Val: 0x03C0

    Reg: 0x01, Val: 0xA400 --> i2c fail (Can't access reg 0x01)

    Reg:0x21 Val: 0x0960

    But, 

    Reg: 0xD1, Val: 0x0204  // PMBus Disable, slew rate 25us 

    Reg: 0x25, Val: 0x0960

    Reg: 0x26, Val: 0x03C0

    Reg: 0x01, Val: 0xA400 --> i2c success 

    See if slew rate is working --> not working.

    Reg:0x21 Val: 0x0960

    So, Please help me with how to get through this.

    Wrap up)

    1) pmbus bit 0 in 0xD1 --> can control i2c addr 0x01 (it's not the same with the datasheet)

    2) addr 0x01 success, but then slew rate is not working

  • 0 in reply to Sangpil Han
    TI__Mastermind 25443 points

    Hello,

    Do not enable PMBUS if you are using I2C. PMBUS is an alternate communication standard that the device can uses. I did make a mistake though. The software trigger is in the TRIGGER register in the PMBUS_MARGIN_HIGH and PMBUS_MARGIN_LOW fields, not the PMBUS register:

    Instead of Reg: 0x01, Val: 0xA400, it should be: Reg: 0xD3, Val: 0x0800 for a margin high trigger. Let me know if this works for you. 

    Best,

    Katlynne Jones