5 Conclusions

This application note presented a measurement methodology for synchronizing measurements between multiple PMBus digital current sense monitors. The use case of synchronized measurements between four INA233 devices was verified and examined in detail. Upon receiving the group command, all INA233 devices trigger at the same time, with some expected variation due to inherent variation in the internal oscillator frequency of each respective device. Addressing order has no effect on the INA233 conversion sequence or timing. Added delay between addresses during the group command has no effect on the INA233 conversion sequence or timing.

Measurement results for a 100Hz ±100mV triangle wave input signal showed that longer conversion time and/or averaging introduced larger measurement mismatch. Thus, for higher amplitude signals, a fast conversion time (for example, 140us) is recommended. Measurement results for a 100Hz ±2.5mV triangle wave input signal showed smaller measurement mismatch. Thus, for lower amplitude signals, longer conversion times can be used without a significant increase in mismatch.

Symmetrical AC input signals are used as test source in this study, however the findings are equally applicable to a DC voltage with a low amplitude AC component which is representative of many power supply applications.