ADS124S08EVM: ADS124S08

Hi Alexander,

Thanks for your reply. Actually I have connected +5V supply from arduino Uno pin to JP9 jumper(1,2 shorted) and common ground to JP11 jumper position(2,3 shorted),then also EVM is powered up and also I don't  need to think about the DVDD voltage. According to my connection DVDD voltage is within the limits and also I am getting supplies of 5 V and 3.3 V  at the J7,J8,J9 side. But you shared one thread also,in that it was discussed that at JP6 position we have to give supply from arduino and related to DVDD supply.  Are my connections right? If I am wrong please correct me.

Thanks.

Regards,

Sushmita Chaudhary

Hi Sushmita,

You need to be very careful when connecting the supplies from the Uno to the EVM. The DVDD digital supply to the ADS124S08 has a very limited range. Even though IOVDD can go to 5V, DVDD cannot and has an operating range limited to a maximum voltage of 3.6V.

If you connect your 5V supply to JP9 while pins 1 and 2 are shorted, you are actually putting 5V on the DVDD_3.3V bus, which will in turn drive the DVDD pin to a voltage that can damage the ADS124S08. JP9 should actually be set to the 5V position (pins 2 and 3 shorted).

If the digital signals on the Uno are 5V, then the IOVDD voltage will be incorrect. If IOVDD is 3.3V and your digital is 5V, then the ADS124S08 could be damaged by exceeding the absolute maximum ratings for the inputs. You are limited to 3.3V + 300mV max.

The Reset pin will be low or floating. For the ADS124S08 to operate, this pin must be tied high to IOVDD.

Best regards,
Bob B

Hi Bob,

Thank you for your explanation. Does it mean that I should connect +5V supply from UNO to pin 2 and pin 3 of JP9?

Thanks. 

Regards,

Sushmita Chaudhary

Hi Sushmita,

Pins 2 and 3 are AVDD supply connections on JP9 that would connect to the 5V supply of the board in normal operation. JP9 has silk screen marked 5V on the top-side of the jumper and 3.3V on the bottom-side of the jumper. You will notice that there is an additional marking above the of 3.3V which is a small dot. The dot on multi-pin jumpers is designating pin 1. Pins 2 (center pin) and 3 (pin labled 5V) are the pins that should be jumpered.

I should have mentioned that you could connect the Uno ground to the testpoints labeled GND as it is easier to connect to these big ground lugs instead of JP11.

Best regards,
Bob B