I'm not an analog / power engineer, but I'm not aware of anything that can
switch up to 4 amps at up to 36 volts to an inductive load without kickback
on disconnect.

And I don't see how a resistive feed is going to overcome the filter
capacitors in a +5 regulated supply.

--
James Newton
1-970-462-7764=20

-----Original Message-----
From: piclist-bounces@MIT.EDU [mailto:piclist-bounces@MIT.EDU] On Behalf Of
RussellMc
Sent: Thursday, October 27, 2011 13:29
To: Microcontroller discussion list - Public.
Subject: Re: [EE] How can any TB6560 driver design NOT violate the chips
spec's?

> Err... were you saying that the TB6560 could be /replaced/ with a design
> that overcomes it's limitations or that the TB6560's limitations could be
> addressed by a proper design?

That a proper design would address the TB6560's requirements properly,
thereby avoiding them being limitations.

eg given what you've said so far it's quite possible that the cheap
designs do not sequence the power supply. The manufacturing cost of
doing so is probably in the $US0.50 - $us1 range. Maybe less. That's
not an insignificant cost. If people can save a $ and it usually works
they probably will.

I was also wondering if you could derive enough power for the 5v or
whatever rail by a resistive feed from the motor rail and a shunt or
whatever regulator. The feed only being needed until the 5V supply
comes up. This may or may not fully meet timing specs but prevents you
ever getting motor volts present and 5V absent.

Anon - the IC looks fully designable for if $ may be spent where
necessary and saved where possible.



    R





>
> --
> James Newton
> 1-970-462-7764
>
> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf
Of
> RussellMc
> Sent: Thursday, October 27, 2011 11:55
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] How can any TB6560 driver design NOT violate the chips
> spec's?
>
> A quick flick through the datasheet suggests that this would be easy
> enough to do if you wanted to do it properly. Motor current capability
> of the IC is modest - under 2A at <=3D 40V I think. A single high side P
> Channel MOSFET in the common VMA/VMB feed would allow supply
> sequencing. Effects of inductive load can be designed for. I'd suspect
> that the cheap and nasty drivers fail because they are not prepared to
> design properly.
>
> TB6560
> $6/1.
> $2.60/10000
> $487.50 callout fee, travel, tax, dinner, E&OE, YMMV.
>
> Suitable MOSFT (there will be cheaper).
> $1.45 /1
> About $0.050/1000
> Prices:
> http://search.digikey.com/us/en/products/IRFU5410PBF/IRFU5410PBF-ND/81241=
6
> Data: =A0http://www.irf.com/product-info/datasheets/data/irfr5410pbf.pdf
>
> DPak.
>
>
> Russell
> --
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