2017-09-14 11:10 PM
Thank you for your patronage.
I am planning to make 1.2V of the picture below with DAC. Is there any problem? I am a beginner, so I care whether this kind of thing is allowed.
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2017-09-14 11:55 PM
If R2 and R1 are high enough, so that the maximum current of the DAC will not be reached then i see no problem. The amplifier has normaly a very high input impedance, so that you will not get any current problem with it.
But you have to think about, if the switching noise from the DAC is okay for you. The 1.2V will not be perfect straight.
Best Regards,
Mathias
2017-09-14 11:55 PM
If R2 and R1 are high enough, so that the maximum current of the DAC will not be reached then i see no problem. The amplifier has normaly a very high input impedance, so that you will not get any current problem with it.
But you have to think about, if the switching noise from the DAC is okay for you. The 1.2V will not be perfect straight.
Best Regards,
Mathias
2017-09-16 05:14 AM
Dear Mr./Ms. Mathias Zviedris
Thank you for your reply. I calculated the current flowing through R2. Its value was 0.1 mA.
Is the switching noise from the DAC so large?
From a beginner like me, I think that there is almost no switching noise.
If you were in my position, do you agree to make 1.2 V with DAC? Or should I make 1.2 V in a different way?
Best Regards,
Ken Inoue
2017-09-16 07:25 AM
I calculated the current flowing through R2. Its value was 0.1 mA.
This value shouldnt be a problem for the DAC.
Is the switching noise from the DAC so large?
It depends on what is 'large' for your application. In my applications i dont recognize it. But its there.
If you were in my position, do you agree to make 1.2 V with DAC? Or should I make 1.2 V in a different way?
I would suggest, that you read the application note AN4566 and build with this info your own opinion.
You have to think about, that the DAC output also depends on the Vref voltage ---> Look in the AN4566.
If you have no high requirements why dont you use an external voltage devider ?
2017-09-16 09:32 AM
Dear Mr./Ms. Mathias Zviedris
Thank you for your quick reply. AN4566 gives me important information. I
have to think about, that the DAC output also depends on the Vref voltage. I want to reduce the number of parts as much as possible, so I would like to make 1.2 V with DAC. But, I also want to consider using external voltage devider.
Thank you for your kindly responses.
Best Regards,
Ken Inoue
2017-09-17 01:42 PM
Using a precision voltage reference would only use 3 parts. The reference, a resistor, and a capacitor. It's extremely accurate, stable over time, and clean. But it does add cost.