J
jimi
- Jan 1, 1970
- 0
Does anyone know of an alternative for the 74C925 chip for driving 4x7
segment LED's. The chip seems to be obsolete. Thanks
segment LED's. The chip seems to be obsolete. Thanks
I've never dealt with this company, but your 74C925 does show up in a seach.jimi said:Does anyone know of an alternative for the 74C925 chip for driving 4x7
segment LED's. The chip seems to be obsolete. Thanks
jimi said:Does anyone know of an alternative for the 74C925 chip for driving 4x7
segment LED's. The chip seems to be obsolete. Thanks
Maxim has some super duper new LED drivers.Use a programmable logic device or an Arizona Microsystems PIC
processor - I'm not far enough into either option to identify a part
which comes in the right 16-pin 0.3" dual-in-line package (and it
might be difficult to find a programmable logic device with enough
buried flip-flops to do the job in an essentially obsolescent package)
but somebody will know.
Don said:Maxim has some super duper new LED drivers.
Does anyone know of an alternative for the 74C925 chip for driving 4x7
segment LED's. The chip seems to be obsolete. Thanks
Thinking out loud,jimi said:Thanks for the replies, however, I asked the question so I could avoid
using a microcontroller.
A small microcontroller, however, would be my first choice.
I'd prefer a programmable logic part - the 4-digit counter is not
synchronous with the multiplexing logic for the display. Back in 1972 I
dealt with this problem by freezing the multipexing clock until any
incoming count had rippled through the (asynchronous) counters, which
took up to 4usec. This wasn't an elegant solution. With a
microcontroller, I guess you'd rely on the interrupt system to capture
clock increments that occured at the wrong instant, and you'd keep your
interrupt handler short and quick to keep the maximum count rate
respectable.
Programmable logic offers true parallel processing, which can be a lot
tidier.
Thanks for the replies, however, I asked the question so I could avoid
using a microcontroller.
So you wnat the OP to replace a 16-pin DIP with a 28-pin DIP that
Intersil has marked "inactive".
I'd prefer a programmable logic part - the 4-digit counter is not
synchronous with the multiplexing logic for the display. Back in 1972 I
dealt with this problem by freezing the multipexing clock until any
incoming count had rippled through the (asynchronous) counters, which
took up to 4usec. This wasn't an elegant solution.
Yes just the filament supply for all those 12AT7's must have been
unwieldy, to say the least.
---
I don't know what you were doing in 1972 - the fact that you haven't
yet got past 555's does suggest that you aren't an early adopter
- but
my toy used TTL logic and Beckman 7-segment fluorescent displays, with
a few transistors to handle the voltage swings.
And not a filament in sight (nor any hidden filaments either)
---
I'd say that statement more nearly categorizes your position than
mine since I adopted them way back when they first came out. You,
on the other hand, have yet to use one (by your own admission) so
I'd say you're the one who's a little late getting on the bandwagon.
---
---
Sorry, Charlie, but vacuum fluorescent displays _do_ have filaments.
Where do you think the electrons used to illuminate the phosphors
come from, otherwise?
On Sat, 02 Dec 2006 08:42:44 -0600, the renowned John Fields
The Beckman displays were flat panel plasma discharge displays, sort
of like Nixies but segmented and with the segments all in one plane.
You used to seem them on gas pumps until fairly recently as well as
some industrial instruments (Simpson had a fairly successful series of
instruments that used them). National semi made a biplar driver chip
DS8880 or something like that.. ah, here it is:
http://www.sphere.bc.ca/test/nixies/ds7880.pdf
John said:---
I'd say that statement more nearly categorizes your position than
mine since I adopted them way back when they first came out. You,
on the other hand, have yet to use one (by your own admission) so
I'd say you're the one who's a little late getting on the bandwagon.
---
---
Sorry, Charlie, but vacuum fluorescent displays _do_ have filaments.
Where do you think the electrons used to illuminate the phosphors
come from, otherwise?
---
discharge" discharge mechanism - in a low pressure of some noble gasFrom positive ion bombardment of the negatve electrode - the "glow
Does anyone know of an alternative for the 74C925 chip for driving 4x7
segment LED's. The chip seems to be obsolete. Thanks