ADS1296R Upon Power Up DRDY Line never goes low

Mike Kemmerer

Other Parts Discussed in Thread: ADS1296R

Hello,

I am new to this forum. I have designed a custom PCB using a microcontroller to communicate with an ADS1296R. Upon initial power up the DRDY line never goes low, which makes me believe that there is an error in device setup/power up sequence. For signals I am using the internal oscillator, internal reference voltage, START is pulled high, RESET is pulled high and then pulsed low and back to high after 1 sec in order to issue a POR. Any and all help would be greatly appreciated.

Michael

over 8 years ago

0 Praveen Aroul over 8 years ago

TI__Mastermind 49666 points

Hello Michael,

I've moved this post from the Medical Forum to the Precision Data Converter Forum, where the ADS1296R is supported. I'm sure you'll find an answer here.

0 Brian Pisani over 8 years ago

TI__Mastermind 38745 points

Hey Michael,

If START is held high constantly then it should definitely start to pulse at some point following the reset. Since that is not happening then it makes me think there could be a hardware issue. Can you share your schematic?

Brian

0 Mike Kemmerer over 8 years ago in reply to Brian Pisani

Prodigy 40 points

FinishedBoards.docx

0 Mike Kemmerer over 8 years ago in reply to Mike Kemmerer

Prodigy 40 points

Thanks Brian, I attached above a word document with snap shots of the finished boards, essentially there are 8 unity gain op-amps connecting to the 8 input channels (only 6 are used as the chip we are currently testing is the ADS1296R) and then that is controlled with a SAM3S4A Cortex M3 processor. From the power supplies we are getting 3.3V, 1.5V and -1.2V (designed to -1.5V). DGND and AGND are the same on the PCB, but differentiated on the schematic to help me remember to separate the ground connections to different areas of the board if possible.

Thanks for the help in advance!

0 Brian Pisani over 8 years ago in reply to Mike Kemmerer

TI__Mastermind 38745 points

Hey Mike,

I believe I have identified the issue. Pin 35 is the active low power-down input pin. In your schematic it is floating. If this pin is not driven high then the device may not power on correctly.

Brian

0 Mike Kemmerer over 8 years ago in reply to Brian Pisani

Prodigy 40 points

You are a lifesaver man!! Wired up that pin to an unused pin on the MCU and immediately started pulsing at 250Hz. Thanks again for the help!!

Data converters

Data converters forum

ADS1296R Upon Power Up DRDY Line never goes low