I saw one of your videos said that the MP6540 family had a bidirectional current sense. But from Figure 1 in the data sheet of the MP6540H it appears to only measure the the Low side FET. Is there another version of this chip that Monitors the High side as well? This chip is awesome and tiny. True Bidirectional Current sense would make it even cooler. In my application, I have a configuration when I’m using an MP6540 like chip to drive an external solenoid that is connected via a separate ground path. I was going to have a separate bidirectional current sense resistor, but if their is a flavor of the 6540 or similar chip which has true bidirectional current sense that would be very useful for cutting my parts count. When we settle on a chip we will buy about 500 of them in 2023. Thanks in advance for your advice.
Hi eldenc,
The MP6540H does in fact have bidirectional current sense. To help illustrate this, please see the graphic below from this video explaining how BLDC motors function (time stamp 10:20). You’ll see that individual power paths (including the respective LS-FET) energize the coils one at a time and the current alternates direction to change the magnetic polarities depending on which path is conducting.
The SOA/B/C pins either source or sink current that is proportional to the current flowing in the LS-FET of each phase. This current is sensed in both forward and reverse directions. So, when a phase is energized, you will be able to see a current reading with a polarity on the corresponding SOx pin (Pg. 13, Current-Sense Amplifiers).
