DRV8323R: Which ground does the shunt amplifier reference?

Oskar Weigl

Part Number: DRV8323R

The shunt amplifier has a common mode input range of +/- 0.15V, but it is not specified with respect to which ground this is. The amplifier's output is also referenced to some ground, and to properly design the downstream analog circuits, we also need to know which ground is referenced.

Given the layout recommendations for how to connect vref, as well as the proximity to the SO pins, one would be led to believe that the shunt amplifier is referencing DGND. Is this correct?

Thanks!

over 7 years ago

0 Rick Duncan over 7 years ago

TI__Guru** 114905 points

Hi Oskar,

We will investigate and reply soon.

0 Nicholas Oborny over 7 years ago

TI__Mastermind 21305 points

Hi Oskar,

The amplifier block is referenced to AGND pin for its ground (the amplifiers and reference buffer). Note that all grounds in the chip are internally connected through antiparallel diodes for ESD protection.

Sorry for the confusion, your assumption is probably what I would assume as well. DGND is a spare ground pin on the DRV8323R connected to ground ring of the chip. DGND was name assigned just to differentiate from other ground pins.

0 Oskar Weigl over 7 years ago in reply to Nicholas Oborny

Prodigy 80 points

Hi Nick,

Thanks for clearing that up. Does this mean that I should avoid SPI communication during running operation, to avoid the return current of the digital signals (and their inductance) to interfere with the analog signals?

Thanks!

0 Nicholas Oborny over 7 years ago in reply to Oskar Weigl

TI__Mastermind 21305 points

Return currents of the SPI internally is likely of minimal impact to noise level. SDO is open drain with external pull up to power supply. For best, best performance you should not use SPI during amplifier readings, but in reality I doubt it will be measurable impact.

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DRV8323R: Which ground does the shunt amplifier reference?