A customer is having an issue:
We have been struggling to find an answer to a tolerance issue related to the DRV8301 driver chip that we use in a lot of our products now. Occasionally, we are finding that the voltages we measure on SO1 and SO2 current amplifier output pins are not within the tolerance range specified on the DRV8301 datasheet with zero current flow to the current amplifier inputs. The datasheet says that these outputs should have an output bias voltage of:
Output Bias with zero input current = (0.5 * Vref) ±0.5%.
However, occasionally we will have a DRV8301 not meet the specified tolerance. For example, one of our controllers had these readings:
REF Pin 24: 4.952V
SO1 Pin 25: 2.573V
SO2 Pin 26: 2.568V
SO1 and SO2 should be in the range of 2.464 – 2.488 to be within +/-0.5% of REF voltage. However, they are out of range by as much as 3.2%.
We need to know from TI if the +/-0.5% tolerance is correct, and if so, why would some DRV8301 chips not meet this specification. Moreover, if these current amplifier outputs are not within spec, is there concern that the DRV8301 may not function reliably in the future? We can account for the tolerance through calibration of our controller, but we do not want to ship these controllers to customers if the DRV8301’s are prone to premature failure.
Thank You.