higher voltage 74HC595
Archiver
Posts: 46,084
Is there an equivalent to the 74HC595 that can handle 24 volts? I
am trying to control a matrix of 4 x 4 lamps that are 24 volts and
can draw up to 200 mA each.
I know that I can put it some source drivers but I have little space
on my PC board to do this and would rather only use to IC along with
the stamp.
Many thanks
Al
am trying to control a matrix of 4 x 4 lamps that are 24 volts and
can draw up to 200 mA each.
I know that I can put it some source drivers but I have little space
on my PC board to do this and would rather only use to IC along with
the stamp.
Many thanks
Al
Comments
>Is there an equivalent to the 74HC595 that can handle 24 volts? I
>am trying to control a matrix of 4 x 4 lamps that are 24 volts and
>can draw up to 200 mA each.
Yes - and no.
Let me explain.
TI makes some neat shift registers with built in MOSFET output
drivers. They are sinking only: they do not source.
The TPIC6C595 has the same pin-out as the 74hc595 and is good for 100 mA /
50V max. Note the "c" in the part number.
The TPIC6595 has a different pin-out from the 74hc595 but is good for 250
mA per output. Note that there is no letter between the "6" and the "595".
Since you are doing a matrix, you need sourcing drivers as well as
sinking. My recommendation is to just use emitter followers: add some 4k7
pullup resistors to the outputs of the TPIC, then connect the outputs to
the bases of NPN transistors. The collectors all go to your +24V supply,
the emitters go to the loads. 2n4401 transistors are just fine up to a
couple hundred mA.
Note that you will also have to diode isolate each lamp at each X-Y
intersection. If you don't, the selected light will be at full brightness,
the 4 lamps that surround that light will be at half brightness, the 16
lamps that surround those (if the matrix was big enough) are dimly
lit. Draw it out if you are not sure what I mean: imagine one of the
middle lines in each axis are energised, then follow the current. You will
see that the sneak paths formed by the filaments of the bulbs surrounding
the selected bulb cause those bulbs to light up. Of course, this may be a
desired effect.
We used to make some matrixes for the night club industry (disco clubs)
years ago - most were conventional in that sneak paths didn't matter. For
the few installations where it did, we used a big bridge rectifier at the
front end so that we had a full-wave pulsating DC supply, then used a small
series diode (1n4005) at each lamp.
Note also that your DON'T have to do this if you are driving LEDs - those
only conduct in 1 direction and there are no sneak paths.
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.
dwayner@p... writes:
> At 05:47 PM 6/29/02 +0000, brownstamp wrote:
> >Is there an equivalent to the 74HC595 that can handle 24 volts? I
> >am trying to control a matrix of 4 x 4 lamps that are 24 volts and
> >can draw up to 200 mA each.
>
Use your 595 to drive a Darlington ULN2003. 7 channels, each will handle
500ma up to 50 volts.
I'm doing that to drive 16 relays.
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
> In a message dated 6/29/02 15:42:59 Eastern Daylight Time,
> dwayner@p... writes:
>
>
> > At 05:47 PM 6/29/02 +0000, brownstamp wrote:
> > >Is there an equivalent to the 74HC595 that can handle 24
volts? I
> > >am trying to control a matrix of 4 x 4 lamps that are 24 volts
and
> > >can draw up to 200 mA each.
> >
>
> Use your 595 to drive a Darlington ULN2003. 7 channels, each will
handle
> 500ma up to 50 volts.
>
> I'm doing that to drive 16 relays.
>
> Sid
Thanks Sid,
Would the TD62783AP work? it is an 8-channel - 500 mA/ch and up to
50V.
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]
>Use your 595 to drive a Darlington ULN2003. 7 channels, each will handle
>500ma up to 50 volts.
>
>I'm doing that to drive 16 relays.
The original poster had asked for a single chip solution since he was
running low on board space. The TPIC6x595 chips are a single chip solution
as compared to your 2 chip solution.
Something else for you to consider though: you can get the ULN2003 in an 8
wide package. The part number is ULN2803. This is identical to the '2003
except that it has 2 extra pins (18 pins instead of 16) and has 8 drivers
instead of 7. This can reduce your chip count if you are working with byte
wide groups.
We used to use thousands of UNL2803 chips in conjunction with thousands of
4094 or hc595 shift registers. After we discovered the TPIC series of
power shift registers, our usage dropped considerably - now we buy
thousands of TPIC6595 chips instead. It makes for smaller and easier PCB
layouts and generates less heat to get rid of - the TPIC outputs saturate
at a much lower voltage than the darlington outputs on the ULN2x03 chips.
If you are working with something that needs more current than what the
TPIC6595 can handle, there is also the TPIC6A595 (note the "a"). This
again has a different pin-out than the other TPIC parts but is good for 350
mA continuous (1.1A peak).
dwayne
--
Dwayne Reid <dwayner@p...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
(780) 489-3199 voice (780) 487-6397 fax
Celebrating 18 years of Engineering Innovation (1984 - 2002)
.-. .-. .-. .-. .-. .-. .-. .-. .-. .-
`-' `-' `-' `-' `-' `-' `-' `-' `-'
Do NOT send unsolicited commercial email to this email address.
This message neither grants consent to receive unsolicited
commercial email nor is intended to solicit commercial email.
brownstamp@y... writes:
> Thanks Sid,
>
> Would the TD62783AP work? it is an 8-channel - 500 mA/ch and up to
> 50V.
>
I'm sure it will. If you have to buy something the ULN2003 are dirt cheap.
That's why I use them. Good luck
Sid
[noparse][[/noparse]Non-text portions of this message have been removed]
that I've used on several project that will handle 24v output. This ship
will cascade to many outputs
Original Message
From: brownstamp [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=O428DTwCmujOVPGT2I8VI4OiQ3wEHEP1buy_qHDhvOdXKEfAYYp5p1bpSsMnE0UVOrUS-6QE5m7Oaw]brownstamp@y...[/url
Sent: Saturday, June 29, 2002 1:48 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] higher voltage 74HC595
Is there an equivalent to the 74HC595 that can handle 24 volts? I
am trying to control a matrix of 4 x 4 lamps that are 24 volts and
can draw up to 200 mA each.
I know that I can put it some source drivers but I have little space
on my PC board to do this and would rather only use to IC along with
the stamp.
Many thanks
Al
To UNSUBSCRIBE, just send mail to:
basicstamps-unsubscribe@yahoogroups.com
from the same email address that you subscribed. Text in the Subject and
Body of the message will be ignored.
Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
[noparse][[/noparse]Non-text portions of this message have been removed]
get this part are all out of stock and with a min of 6 weeks lead
time to order. I also managed to get one chip from Allegro to try
but could never get the darn thing to work. I am programming it
exactly as you would the 74HC595 (am I wrong?) and can't get it to
go.
Any idea where to get this chip (Newarks, NuHorizon don't have
them. Could you share how you managed to address this chip?
thanks
Al
--- In basicstamps@y..., Sadler Porter <porter.sadler@s...> wrote:
> Allegro make a chip that will handle( ucn5841a shift in / 8
parallel out)
> that I've used on several project that will handle 24v output.
This ship
> will cascade to many outputs
>
>
Original Message
> From: brownstamp [noparse][[/noparse]mailto:brownstamp@y...]
> Sent: Saturday, June 29, 2002 1:48 PM
> To: basicstamps@y...
> Subject: [noparse][[/noparse]basicstamps] higher voltage 74HC595
>
> Is there an equivalent to the 74HC595 that can handle 24 volts? I
> am trying to control a matrix of 4 x 4 lamps that are 24 volts and
> can draw up to 200 mA each.
>
> I know that I can put it some source drivers but I have little
space
> on my PC board to do this and would rather only use to IC along
with
> the stamp.
>
>
> Many thanks
>
> Al
>
>
> To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@y...
> from the same email address that you subscribed. Text in the
Subject and
> Body of the message will be ignored.
>
>
> Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
>
>
>
> [noparse][[/noparse]Non-text portions of this message have been removed]