DAC7716: Reference voltage circuit for DAC7716

MESH

Part Number: DAC7716
Other Parts Discussed in Thread: REF5050, REF5025, TMUX6136

Hello,
I am considering the circuit using DAC7716.
I consider referenece voltage circuit to REF-A input pin on DAC7716.
Reference voltage circuit will use REF5050, REF5025, and TMUX6136.
The analog switch IC TMUX6136 is used for switching of reference voltage of 2.5V or 5.0V to REF-A input pin on DAC7716 at the initialization timing .
The internal gain setting of DAC7716 will use only x4.
And output voltage ranges of DAC7716 will +/-10V, +/-5V, and 0V to +10V. (AVDD = +15V and AVSS = -15V)
Control signal for TMUX6136 (SELx) is provided from GPIO output on DAC7716.
I'm thinking of using an analog switch IC TMUX6136 to switch the reference voltage, but I need advice on whether or not this will cause problems with the operation of the DAC7716.

Regards,
MESH

over 3 years ago

0 MESH over 3 years ago

Intellectual 850 points

My computer wasn't working well and I got multiple posts.
I feel bad.
The latest questions is this post.

+1 Akhilesh K over 3 years ago in reply to MESH

TI__Mastermind 18886 points

Hi,

Since the REF input of DAC7716 is high impedance, I am not seeing any issues.

DAC7716 ref input has min 10Mohms input impedance. You may need to account for the switching characteristics of the MUX.

I will close other threads and we will continue discussion on this thread

Regards,

0 MESH over 3 years ago in reply to Akhilesh K

Intellectual 850 points

Hi, Akhilesh K

Thank you for your reply.

The switching characteristic of TMUX6136 is approx 200nsec, but please let me know if there are any points to note.

Although it is not a switching characteristic, I am thinking of adding a 10Mohm pull-down resistor to the REF INPUT pin of the DAC7716 for a leakage current of 1.6nA from the drain pin of the TMUX6136.
If you have any comments regarding the addition of this pull-down resistor, please let me know.

Regards,
MESH

+1 Akhilesh K over 3 years ago in reply to MESH

TI__Mastermind 18886 points

Hi,

Like I mentioned, DAC7716 reference input is high impedance. I don't see any issues by adding 1Mohm pull down resistor.

Regards,

0 MESH over 3 years ago in reply to Akhilesh K

Intellectual 850 points

Hi, Akhilesh K

Thank you for your reply.

Your reply is very helpful for me.

I will try adding 10Mohm pull down resistor at circuit evaluation using prototype board.

Regards,

MESH

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DAC7716: Reference voltage circuit for DAC7716