DAC8812: Not sure about ESD protection and continuity test best practice

Pablo Sulecio

Part Number: DAC8812
Other Parts Discussed in Thread: DAC8802

Hi Everyone

I'm working on a test solution for the DAC8812 and DAC8802 and I want to test continuity in the analog pins, however I want to make sure I'm doing the right thing. Referring to figure below.

I noticed that pins VrefX, RFBx and IoutX can take positive and negative values of + -Vref ( max allowed range is [-15V to + 15V]) so I assumed that there are not protection diode on those pins, am I right?
To test continuity in pins RFBx and IoutX I will force current through RFBx and read voltage between pins RFBx and IoutX, I will need S1 to be closed, this is accomplished by power on VDD; however I am not sure how to measure continuity in VrefX pins, I read VrefX pins have a constant impedance of 5K +-20% is that the case when VDD is off? or should I power on VDD and reset the DAC registar and measure the voltage between Vref and AGND?

Do you think there is a better Technic to Test those pins?

For the Digital pins I will force -100uA and measure the zener forward voltage, and for VDD I will force -100uA and Measure the 2 zener forward voltage in series, according to the image bellow... will be that enough?

Or is there other protections I should be awarded of ?

over 6 years ago

0 Paul_Frost over 6 years ago

TI__Guru 53673 points

Hi Pablo,

Someone from our team will get back to soon.

Thanks!
Paul

0 Uttam Sahu over 6 years ago in reply to Paul_Frost

TI__Genius 14220 points

Hi Pablo,

Thank you for your query.

You are right about the VREFx and RFBx that they can go upto +/-18V abs max. However, the IOUTx pin can go only upto VDD.

Typically, to test the continuity, we force a current of around 50uA to the respective pin and measure the voltage. For digital pins, you are right that the voltage should be measured across the ESD diodes.

For analog pins, VREFx can be tested by supplying the current and measuring voltage across the equivalent impedace to ground. You need to have VDD on.

RFBx can be tested similarly with respect to IOUTx after switching on VDD.

For IOUTx, you can test w.r.t. ground and VDD.

Hope that answers your query.

Regards,
Applications Engineer, Precision DACs

0 Pablo Sulecio over 6 years ago in reply to Uttam Sahu

Intellectual 290 points

Hi Uttam, thanks a lot for your respond, so IOUTx pins have the following connection: ?

Meaning it can be tested by applying current through EDS diodes?

0 Uttam Sahu over 6 years ago in reply to Pablo Sulecio

TI__Genius 14220 points

Hi Pablo,

I think so. I will check with the design team and confirm.

Regards,
Uttam

0 Uttam Sahu over 6 years ago in reply to Uttam Sahu

TI__Genius 14220 points

Hi Pablo,

Sorry for the delay. I am yet to get a response from the team. I will update in a couple of days.

Regards,
Uttam

0 Uttam Sahu over 6 years ago in reply to Uttam Sahu

TI__Genius 14220 points

Hi pablo,

I got a confirmation from the design team that there are ESD diodes on IOUTx to VDD and GND.

Hope that answers your question.

Regards,
Uttam

0 Pablo Sulecio over 6 years ago in reply to Uttam Sahu

Intellectual 290 points

Hi Uttam,

That completely answered my questions!!

Thanks a lot for your help!

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DAC8812: Not sure about ESD protection and continuity test best practice