There is a space on the single chip VNH5019 driver for an additional capacitor. What are the recommended specifications, and/or the mfg and mfg pn’s for the cap.
I am driving Pittman 24V dc motors through about a 3 meter length of cable 18 or 20 gauge.
Additionally, I plan to use PWM from the pins of an Arduino Mega. The specifications are a PWM frequency of about 490 Hz, this seems quite a bit less than the capabilities of the chip. Does this frequency propagate through to the output? I.E. is the PWM output at 490 Hz or some other value? Reading the data sheet seems to imply that.
An extra capacitor is not normally required to use our VNH5019 carrier, but it would probably good to add one in your application since your are powering the board from long wires (a few hundred microfarads with a voltage rating significantly higher than your supply voltage should be fine). However, while the over-voltage protection on the VNH5019 typically kicks in at 27V, it can trigger at voltages as low as 24V, so this board may not be the best choice if you are using a 24V supply. Instead, you might consider one of our G2 High Power Motor Drivers, which are also available as dual driver shields with form factors that interface neatly with Arduinos like the Arduino Mega.
The PWM signal applied does propagate to the outputs on both the VNH5019 and the G2 High Power Motor Drivers. You can get a higher PWM frequency than 490Hz from your Arduino, but that will require some more complex programming.
I am most interested in the specification of the caps. And or brand, PN. Should I stick with 47 microFarads or go higher/lower. I would just like to get some ordered, Mouser, Digikey, Allied.
The real problem is I don’t have a spec. or package size or is this meant to be supplemented with a radial lead capacitor. The ones currently on the board package very well.
I’ve not really had problems with voltage or power and have built several systems. The power supplies can be dialed back a smidge from 24V.
I am aware of several methods of altering the output frequency
My recommendation was to add a radial capacitor to supplement the one already on the board. Any capacitor that will fit with a capacitance of a few hundred microfarads and a voltage rating significantly higher than your supply voltage should be fine; it does not need to have exactly the same ratings as the one already on the board. The through holes circled in the picture below are spaced to work well with 8mm or 10mm caps, but other sizes can probably work as long as the leads can be fitted in the holes.
Thank you very much Patrick. We’ve built about 10 systems with these, 5 drivers per system. We’ve not had any issues to date. I will probably play around with our in-house prototype to see how much it helps.
We are driving motors that are not heavily loaded, so other than the first few mS, we aren’t averaging a current draw greater than 1 amp, and that is for perhaps 30 seconds. In addition, the duty cycle is quite low.
Thanks again for your help. I didn’t realize until after I replied to your first post that this is probably designed for radial lead caps, not the surface mount type that is on the driver to start. That would actually be a pain if it was.
