How to adjust the ADuM4190 EAout2 BIAS

Hello,

The 5 V internal clamp of the ADuM4190 is provided to protect the EAout2 pin from going higher than 5 V. Operating below 5 V is a valid output state. the EAout2 pin should be pulled up to a value between 3 V and 20 V. This limit is described in page 14 of the Rev. 0 datasheet:

The EAout2 pin will work fine being pulled to 5 V through an external resistor.

What voltage is the IN- pin at?

Please let me know if you need any further clarification.

RSchnell

Thanks for explains.

The IN- is connectted to comp. Yes, the EAout2 is clamp to 5V internal.

The DC voltage of EAout2 is about 4.5V. When the signal AC voltage on EAout2  is bigger than 1V, the EAout2 output will be distortion. 

We want to know is there any methods to adjust the DC voltage(about 4.5V) on EAout2 to lower.

Thanks a lot!

Hello,

Do you have a waveform capture of the IN+ pin and the EAout2 pin?

Is your input signal a 1 V peak to peak AC signal with a bias?

Thanks,

RSchnell

Hello

Yes, it is AC signal without  any bias. A capacitor is on the IN+ and the R601 is not loaded.

Here is the schematic and the waveform.

Thanks.

Eleven

Hello,

Thanks for the waveform. It appears that there is a common mode being introduced on the -IN pin that could be causing the clipping. The valid linear range for this part is 0.35 V to 1.5 V. Are you able to reduce the 2.5 V common mode?

Additionally, the pull-up resistor for the Eaout2 pin is a little too strong. The datasheet limit for the current in EAout2 is 1 mA, so for a 5 V supply, you must use 5 kΩ or larger for for R605.

OK，Thanks for you helps.

OK，Thanks for you helps.