William Bross said:
> We use a lot of TPIC6C595 from TI.
Hi Bill,
I am remembering a thread a year or two back regarding that particular
part (as opposed to the TPIC5B595, the bigger brother). Something about
them latching up or just glitching badly under certain circumstances. Have
you had any experiences like that with the TPIC5C595?
Yes, I remember quite a few people sharing their 'experiences' both good
and bad about the TPIC chips. I just did a search in the archives on
TPIC6C595 and located some of them. It seems that it was the 6595 - the
higher current version -that had a bunch of glitching problems. I've
got a couple hundred C595s out in the field over the last year without a
single problem. But I did keep the total current per pin down between
10 to 75 mA. Can't beat them for driving LEDs - from a single one up
through the multi-LEDs in series seven segments displays. They are
fast, cheap and easy to interface. In fact, my current driver is just a
revamped version I used back in '92 with a 16C54 driving an HC595 and 4
AlGAs 7 seg. displays.
By the way, I did notice one of the threads said that the 6C595 was the
same pinout as the HC595. It's not even close. I only had hc595s for my
first prototype and I had to do quite a bit of rewiring when the new
chips came in.
On 30 Jan 2004 at 13:57, Bob Blick wrote:
> William Bross said:
> > We use a lot of TPIC6C595 from TI.
>
> Hi Bill,
>
> I am remembering a thread a year or two back regarding that particular
> part (as opposed to the TPIC5B595, the bigger brother). Something
> about them latching up or just glitching badly under certain
> circumstances. Have you had any experiences like that with the
> TPIC5C595?
I've used the TPIC6A595 (350mA per output) with zero problems. I've tried
short circuit to +12V and GND and they just keep on going, 400+ units in
service with no reported failures (touch wood). Good PCB layout is said to be
important though.
I just bought a bunch of Fairchild MM74HC595's from Digikey. Decent pricing
and up to 70 mA from each pin. I'm using them to drive a bunch of high
intensity LEDs, and the chip doesn't even get hot at 30-40 mA (I haven't
tested it above that). I'm not sure of the open-collector outputs... In my
case it doesn't matter, since I'm using it to ground the LEDs rather than
drive them.
On Friday, Jan 30, 2004, at 10:34 US/Pacific, Robert Ussery wrote:
> I just bought a bunch of Fairchild MM74HC595's from Digikey. Decent
> pricing
> and up to 70 mA from each pin.
I don't think you're reading the datasheet right. 70mA on Vcc/GND,
35mA per output pin. And those are the "absolute maximum" currents,
not the normal rated drive current. I don't see the later, which
probably means it's off in the "74HC family specifications", but it
does say "drives 15 LS-TTL loads. That's 1.5mA each, isn't it, for
a total of about 24mA (which IIRC is the standard for this sort of
logic. But it's unfortunately rather just below where I'd want it
to be for anything bigger than LEDs...
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Hulatt, Jon wrote:
> So, to complete the repair, i need a single 10 ohm, ideally 0805
> sized (but a 0603 would do) resistor. I haven't found anywhere that
> will sell me less than a reel's worth, which is a bit ott.
Since it's a one off, just use a normal 1/4 watt resistor with the leads
bent appropriately.
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*** MESSAGE TRUNCATED ***
>I am remembering a thread a year or two back regarding that particular
>part (as opposed to the TPIC5B595, the bigger brother). Something about
>them latching up or just glitching badly under certain circumstances. Have
>you had any experiences like that with the TPIC5C595?
That may have been me. Believe it or not, there are *4* variants in that
family: '6595, '6A595, '6B595, '6C595. Of those, the '6595 & 6B595 have
similar pin-outs (2 extra ground pins in the '6595 that are unused in the
'6B595).
We had enormous problems with the '6B595 that were tracked down to the chip
itself. All of those problems went away when we switched to the '6595. We
use the TPIC6595 by the thousands with no problems whatsoever.
The '6C595 ("C" variant) has the same pin-out as the 74hc595 and could be
dropped into the same socket *EXCEPT* that the data is inverted with
respect to the 74hc595: a serial 1 turns on the output FET, which is a low
side switch.
In summary: the only problem that I've had with the TPIC family is the
TPIC6B595 (the "B" variant).
dwayne
PS - I also use lots of the 74hc595 as LED drivers: LED supply is a
separate 3.3V or 4V supply; 74hc595 operates from 5V supply with active LOW
outputs. They are reliable so long as you keep the total package current
below 80 mA - that is: 10 mA per output. No problems with the LEDs being
reverse biased since 1.7V is well below the maximum allowable reverse bias
spec. Note that it is important to operate the 74hc595 from a 5V supply to
ensure that its output FETs are fully enhanced.
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-----Original Message-----
From: pic microcontroller discussion list
[TakeThisOuTPICLISTspamMITVMA.MIT.EDU]On Behalf Of Dwayne Reid
<snip>
The '6C595 ("C" variant) has the same pin-out as the 74hc595 and could be
dropped into the same socket *EXCEPT* that the data is inverted with
respect to the 74hc595: a serial 1 turns on the output FET, which is a low
side switch.
In summary: the only problem that I've had with the TPIC family is the
TPIC6B595 (the "B" variant).
dwayne
<snip>
Once again, please check your data sheets! These two chips don't have a
single pin assignment in common! Yes, the data is inverted BUT, you can't
interchange the chips!
Bill
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At 09:58 AM 2/1/2004, William Bross wrote:
>The '6C595 ("C" variant) has the same pin-out as the 74hc595 and could be
>dropped into the same socket *EXCEPT* that the data is inverted with
>respect to the 74hc595: a serial 1 turns on the output FET, which is a low
>side switch.
>
>dwayne
>
>Once again, please check your data sheets! These two chips don't have a
>single pin assignment in common! Yes, the data is inverted BUT, you can't
>interchange the chips!
Yep - I just checked the data sheets again and you are right. This bugs
me: I'm positive that I did come upon a power MOS near equivalent of the
hc595 and now I'm going to have to dig in and find it and try to figure out
why I got it confused with the '6c595. This was several years ago and I
wound up not needing to use the part - the 74hc595 worked out just fine as
a LED driver.
But back to the original poster's question: the 2 parts that I have
extensive experience with are the tpic6595 & tpic6b595. The tpic6595 has
been reliable, the '6b595 caused us much grief.
I've also used the tpic6a595 without any problems - but only in
prototypes. I haven't used them in production.
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