I'm excited to see this new DC Motor Driver chip, as the one I've been using (VNH2SP30) has been discontinued. I'd like to try incorporating the current sense into my project, but am unsure how it works. It has 2 pins, SEL0, and CS, and it called it multi sense. Here is the data sheet and on the first page it states:
MultiSense diagnostic functions
– Analog motor current feedback
– Output short to ground detection
– Thermal shutdown indication
– OFF-state open-load detection
– Output short to VCC detection
The only one I am interested in at this point is current sense of the motor, though I'd like to understand how it all works. Table 10 on pages 12-13, and Table 11 on page 18, seem to explain it, I can't quite follow it.
I'm designing my board around eh circuit in Fig 16, page 22. My Supply voltage will be 13.8VDC, and I'll be running a motor that will draw about 4 amps. Looking at Fig 16, What value should I use for Rsense? And do I connect SEL0 to a digital pin thru the 1K Resistor, and the CS to an analog pin thru the 10K?
Is this reading a voltage divider? Thanks
The CS output evidently produces a current that is proportional to the motor current. It can be negative, meaning that you have to take the possibility of negative voltages with a given Rsense.
Agreed, the data sheet does not clearly explain how to use that output, or why there should be four different constants of proportionality associated with it. Perhaps the manufacturer has an application or design note specifically covering that.
I'm very happy with this VNH5019 motor controller, which has a useful (positive only) current sense output, although the proportionality constants are somewhat different for forward and reverse motor current.
Ok, thanks. I'll have to write ST again. I wrote them, but it was over Thanksgiving and my email may have gotten lost in the celebrations!
I have used the VNH5019 as a replacement, it's a drop in replacement pretty much. How ever, it's really a lot bigger than I need. My motor uses about 3-4 amp, maybe 6-8 on startup but not really normally that much. This VNH 7100BAS is so much smaller, it look ideal. There's not much else there in that bracket. Many are for motors like 2 amps.
Thanks.
If anyone else has used or is familiar with the VNH71000BAS on current sense...
CS is multiplexed and can report on various fault conditions as well, depending on the SEL0 and other inputs. See Table 13, although the explanations still leave much to be desired. Those cases probably explain the four K values.