I have a circuit design where I’m using the ACS37800 to measure voltage. I notice the voltage sensing module couples VINN to GND, and couples them both to the negative supply through 2MΩ. Elsewhere in my design I have GND coupled directly to the negative supply, which effectively shorts out this leg of the voltage divider and throws off readings. Has anyone experimented with breaking the VINN to GND link via the jumper pad? This would allow the voltage divider to work properly. The ACS37800 datasheet specifically says that VINN must be connected to GND, but I’m wondering why a jumper pad was placed here at all if that’s the case.
When I designed the ACS37800 board, I tried to make it ‘general purpose’. I tried to cover both the “Voltage Channel Application Circuit; Device GND is Connected to Neutral” and the “Voltage Channel Application; Device GND is Isolated from Neutral” circuit examples. And tried to cover both high-side and low-side DC sensing. I included the VINN-GND jumper because I thought it might be needed. It turned out to be essentially redundant… VINN should always be connected to GND.
By default, the LO terminal isn’t connected to anything and the resistors are floating. You can use a jumper wire to connect LO to IP- if needed.
It sounds like you are doing low-side DC sensing? For you, connecting IP- to GND is probably the right thing to do. To measure the voltage, you’ll need to open the IP+ jumper (which connects HI to IP+), then connect HI to the high side of your load.
Please have another read of the hook up guide and let me know if you have more questions.