The ATS 276/277

Hello. I started this topic because I want to know more about an integrated circuit called ATS 276/277. A few days ago I saw an article with diferent BL motors, one of them using a circuit that includes this chip. I read that article and I understood that this circuit has 2 weak points: big weight and the cases whent the motor doesn't work. I want to make a Motor with this chip,but before all I want to know the main characteristics of it. I have some images with it(and the motor working).

Probabily someone will say: A1442 chip from Allegro is specialy made for this and it's much better than this circuit. I know that. The ATS is easier to find and this circuit is easy to build. But I don't know the value of that two resistors. Do these values depend by the dimensions of the motor? And why the chip is called 27x?

Hi!
I'm sorry I could not reply earlier, I was sick.
Chip ATS 276/277 27X called because it cut.
I mean, instead of writing ATS ATS 276 or 277, we write short 27X.
  Reristors on whom you ask, are the pull-up en.wikipedia.org/wiki/Pull-up_resistor
  Their value can be 1 - 47 kilohms
Sorry for my English.

No problem! But I have seen on the pc board of the CPU fan that there is the integrated circuit without other components. I have seen a circuit without a H Bridge, only two transistors. I believe that the driver works only with ic. I have done the rotator and now I'm trying to make the stator coils, using 7 ohm/meter.

And I saw these chips. But they are rare. Increasingly used powerful operational amplifier + Hall

What`s the smallest voltage of the driver to work?