Hello,
I'm currently an EMC2 user on 3 separate machines using simple step/direction drives.
After doing some research I (like others) became excited about the possibilities of an inexpensive closed-loop servo drive system for my mill using the Pluto-P board and H-Bridges.
Having read the other threads on building a high-power servo drive system using discrete mosfets (Large servo drives on the cheap...) I've decided I'd like to tackle a more modest goal of designing a board that integrates cleanly with the following features:
* Clean integration with the Pluto-P board
* 4 H Bridge drives using one L298 per channel (or other integrated H Bridge)
* Encoder inputs
* Limit switch inputs
* On-board power supply (bridge rectifier, capacitor) - optional
I was initially considering a single L298 per channel, which would offer 4A @ 46V- potentially enough to run my mini-mill.
However, I started browsing mouser for some similar parts - looking for integrated H-Bridges like the L298, possibly newer-tech. I came across a candidate that seems very exciting:
VNH2SP30-E
http://www.st.com/stonline/books/pdf/docs/10832.pdf
It's a fully integrated H-Bridge driver designed for automotive applications.
It's rated at 41V / 30A, uses mosfets internally, with a scant 19mOhm Rds On. at around $9 a piece it seems like a bargain.
Take a look at figure 32 in the datasheet. With the high level of integration it seems like a more sophisticated, next gen version of the L298, with built-in current limiting, thermal-limiting- even includes flyback diodes- CMOS/TTL inputs, everything!
At first glance the chip should be compatible with the pluto-P outputs- I believe all of the equivalent enable/pwm channels map to this device.
My primary concern is the voltage ratings for this device- it shows the absolute maximum Vcc at +41V, but the max operating supply voltage at +16v. Seems like a large discrepancy- possibly there to conform to automotive environments. I do want to know if this device would work reliably near its absolute maximum voltage.
Would like to hear the experts weigh in on this- especially on the viability of the VNH2SP30-E.
In any case, parts are on order for an L298 and VNH2SP30-E configuration. I'll follow-up with more information as I proceed.
Thanks,
Brent