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DAC161S997: adjust slew rate control at which the output current changes

Manop Wangmad
Prodigy 20 points
Part Number: DAC161S997
Other Parts Discussed in Thread: DAC8771, DAC8750, DAC8775, DAC8760

Hello,

 

We’ve implemented DAC161S997 to our new prototype and already tested for 4-20mA output.

We would like to adjust slew rate control by software or hardware to control the rate at which the output current changes to slower rate.

Could you please check and advise how to implement to DAC161S997?

  • 0
    TI__Guru* 93215 points

    Manop,

    For the DAC161S997, we don't have an adjustable slew rate setting for this device. Some of our other analog output devices (like the DAC8775, DAC8771, DAC8760, and DAC8750) have adjustable slew rate settings for the DAC.

    In this device, the DAC161S997 is part of a larger control loop and I don't know of any current designs that have an adjustable slew rate. I'm afraid that I don't have a good recommendation for you for implementing slew rate at this time.

    Joseph Wu

  • 0 in reply to Joseph Wu
    Prodigy 20 points

    Hello Joseph,

    thanks for your replied. 

    Does it possible to increase slew rate by increasing the capacitance of C1, C2, C3 to speed down the transient response of the device?

    They are 2.2nF in our circuit now.

    Regards,

    Manop

  • 0 in reply to Manop Wangmad
    TI__Guru 53183 points

    HI Manop,

    Joe will review and respond on monday.

    Thanks,

    Paul

  • 0 in reply to Manop Wangmad
    TI__Guru* 93215 points

    Manop,

    The short answer is yes. Changes in the values of C1, C2, and C3 do affect the transient response of the device. Unfortunately, I don't have much experience with the changes to these capacitances. The other issue is that the settling time is different for different step changes, but it is not linear to the step size change. I would point to Figure 4 in the datasheet. This figure shows the settling time versus the input step size. 

    Joseph Wu