Hello,
are the power supplies for analog-block VA and for digital-block VD internally connectet?
is it possible to use different power supplies for VA COMA and VD COMD.
This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
Hello,
are the power supplies for analog-block VA and for digital-block VD internally connectet?
is it possible to use different power supplies for VA COMA and VD COMD.
Hi,
These two are not internally connected, you can power up the same with different power supplies. Please note these shares common ground internal to the device ( there is no isolation between COMA and COMD)
Since the recommended operating voltages for both VA and VD are same ( 3.3V), why you want to power them with separate power supplies? As such in a typical implementation( loop powered systems), you want to operate them with the loop regulated supplies. Please see the applications section in the datasheet for more information. We have characterized this device with VA = VD = 3.3V
Regards,
AK
Hello AK,
thanks for the reply, my purpose is to use one MCU to control two DAC161S997s for two current loops. As you said the COMA and COMD are internally connectet, I might need a isolator between the MCU and one of the DAC161S997.
Hi,
Please post the schematics once you are done with your design. I will be happy to help.
I am closing this thread as of now, you can reopen the same once you have done with your design
Regards,
AK
Hello AK,
I have done a simple example for my application, will it work? The IC1 is a digital isolator, it shall pass the data between the mcu and the DAC161S991(U8).
Hi,
I am afraid this scheme will not work here. Your loop power supply is referred to which ground here? looking at the schematics, you want to isolate the two DAC's right and powered up using the same loop supply?
Regards,
AK
Hello AK,
yes you are right, sorry for the mistake. there shall be two seperated 24V supplies.
Hi,
Can you redraw the same and resend? Also we have multiple blog posts explaining this in details.
Regards,
AK
Hi,
This scheme can work, Needs to verify thoroughly.
Did you read the above blogs to understand different tradeoffs in designing multiple isolated 4-20mA transmitters? I am copying one of our Apps engineers who worked on these to comment on the same.
Regards,
AK
Hello AK,
yes I have read the blog, these are really helpful, thanks for your support.
Hi,
Thanks, If Katlynne have any comments on the schematics, she will reply back to you on this thread.
Regards,
AK
Hi Fangzhou,
I notice a few more small errors in this schematic.
Everything else looks ok to me.
Best,
Katlynne Jones