TB6600: Fake or not? But, who cares?
Having been focused on the CNC world as both a hobbyist and electronics designer for a while now, I have been struck by the sheer amount of garbage being peddled on Amazon, eBay and Ali-whatever. One instance that has stood out to me is the TB6600 stepper drivers. These are, supposedly, built around a respectable Toshiba TB6600 IC which sports some serious specs including up 42V Motor Voltage and 4.5A current. A few years ago when I built a small CBeam router, I used TB6600 drivers, shown here on the right. They were inexpensive - around $35 for 4 - and seemed to work just fine. They have performed well in machines with lower end Nema 23 Motors. Not as glamorous as the big enclosed stepper drivers but they work just fine for me.
Fast forward to today and there are lots of TB6600 drivers that look like higher end drivers. What young CNC builder wouldn't want 3 or 4 for their first CNC machine? Except, there seems to be a catch. The TB6600 chip, according to the Toshiba datasheet, doesn't support 32:1 microstepping and yet this new driver has that as an option. Hmmm, fake? I searched the internet for discussions of this and found only supposition based on the magic new microstepping feature.
So, I decided to take a closer look. I ordered one from Amazon - about $11. I know I can find cheaper but wanted to get it quickly. The next day it showed up on my doorstep and what does any self respecting geek do with a new toy? Tear it apart!
The first thing I noticed is that the assembler did a lousy job on the through hole parts. The signal connector is badly misaligned in 2 dimensions and the dual LED header is at a weird angle as well. Slap-dash sweatshop labor? Is this a QA reject? Who knows but it doesn't instill confidence. And the cover that looks like metal? Well, it is simple plastic. Not really an issue but it does contribute to the illusion of a higher end product. The entire back of the driver is a rather large heatsink that gives some comfort in the product being real and the euro style pluggable screw terminals are also encouraging.
With the plastic cover off, the PCB mounted to the metal heat sink/case is revealed. Overall, it doesn't look too bad. But several things caught my eye. A relatively small (and unnecessary?) heat spreader pour in the middle of the board, misaligned 47uF electrolytic capacitor. and two huge through hole sense resistors at weird angles. I would guess the resistors are due to a hasty redesign of the PCB to move away from surface mount sense resistors. The TB6600 pictured above uses surface mount sense resistors. I noted the number on the board - 70725. Searching the internet did not shed any light. Also peering between the PCB and the heatsink, you can see what appears to be an aluminum slug to thermally connect the two. But to answer the core question - TB6600 or not - we will have to pull the PCB off the the heatsink.
With the 2 screws and 2 threaded standoffs removed the chip is revealed. Well, a chip covered in thermal grease anyway but a few wipes of a paper towel gives us the answer. No, it is not a TB6600 but rather a TB67S109AFTG. Still a Toshiba chip, assuming this isn't a fake/remarked chip. Though, I don't know why they would bother to remark a chip that the vast majority of people would never see.
So, we need to turn to the datasheets to see what the differences are. In general, the two chips are more alike than different. They both appear to have similar features with the exception of 32:1 microstepping on the TB67. But when we look at the maximum operating ratings, we see a key difference. The TB6600 is rated to 42V max motor voltage and 4.5 Amp max current. The TB67 is rated at 47V and 3 Amp. So, not only is it not a TB6600, but can only handle 2/3 of the current that the TB6600 can. And, now we know why they lie and say it is a TB6600. Strangely enough, they claim 32:1 microstepping which allows the astute consumer to immediately know it's a fake!
I look at this situation in 2 ways. First, it is fraud. Pure and simple. They are selling you something that simply doesn't perform up to what they claim. And secondly, on it's own merit, this TB67 based driver is actually not that bad. In fact, the way I set up my CBeam router, I have no doubt this driver would work just fine. So, if you are in the market for a driver that you will run under 3 Amps and up to 36 Volts, these market fake TB6600 drivers will probably work for you. It is a little bit like buying a Gucci bag from a street vendor with a wink. The bag will probably do it's job just fine, even though it's not a Gucci.