On Sun, Jan 15, 2017 at 07:17:05AM +1000, David Duffy (AVD) wrote:
> I'm not aware of any PICs that can swing their outputs more than 5V.
> David...

David,

There's no need for more than a 5V swing as long as you are using 2 pin
bi-color LEDs and the forward voltage of both isn't more than 2.5 volts.

It just takes a small trick. What you do is tie one end of the LED to a
2.5V rail and the other end to a PIC I/O pin. You can get all three states
from a single pin:

0V output turns on one color LED
5V output turns on the other color LED
input turns the LED off.

If you have a lot of LEDs, you can create a 2.5V rail using a power supply.
For a few LEDs a stiff voltage divider will do.

BAJ

>=20
> On 14/01/2017 2:16 PM, Anthony Nixon wrote:
> > A surface mount PIC cannot do the job ??
> >
> > cheers
> >
> > Tony
> >
> > On Sat, Jan 14, 2017 at 9:26 AM, David Duffy (AVD)
> > <david@audiovisualdevices.com.au> wrote:
> >> I have an idea for a project that needs to drive 8 outputs for (remote=
ly
> >> mounted) 2-pin bi-colour LEDs.
> >>
> >> Since the LEDs are 2-pin, I'll need to reverse the polarity on them
> >> individually. There may be 1 or 2 LEDs on each output, so if they were
> >> in series that means I need a swing of more than 5V.
> >>
> >> I was thinking of two shift registers arranged as 8 H-bridges, but can=
't
> >> seem to find any that have a Vdd of more than 5V and have an output
> >> current of more than a couple of mA.
> >>
> >> There are H-bridges out there, but the cost and space adds up pretty
> >> quickly for 8 outputs.  Ideally I'd like nothing finer pitch than a SO=
IC
> >> package.
> >>
> >> Any ideas?
> >>
>=20
>=20
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> ___________________________________________
> David Duffy        Audio Visual Devices P/L
> Unit 8, 10 Hook St, Capalaba 4157 Australia
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> Our Web Site: www.audiovisualdevices.com.au
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Associate Professor: Department of Computer Science and Information Technol=
ogy
College of Information and Mathematical Sciences
Clayton State University
http://faculty.clayton.edu/bjeff
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