[sdiy] 7-segment LED displays with 4511 driver chip - max current?

MTG grant at musictechnologiesgroup.com
Wed Aug 5 18:44:33 CEST 2015


Maybe there are internal resistors like this guy has (had?):

http://www.riana.com/electronics/docs/MC14495.pdf

Not that you can see them in the data sheets you supplied though. =:-o

GB


On 8/5/2015 9:32 AM, Rick Jansen wrote:
> I need three 7-segment digits for a small project, and am looking at the
> common 4511 driver to drive them. There are numerous examples around of
> circuits to do just that, but I'm a bit puzzled. The specs for the 4511
> say that it can source 25 mA max current, per pin. However, with a max
> total of 50 mA for the entire package. So, if you light ALL segments,
> excluding the dot, that would be 50/7 = 7 mA max current per segment.
>
> Only TI says 7.5 mA explicitly :
> http://www.ti.com/lit/ds/symlink/cd74hc4511.pdf
> NXP: http://www.nxp.com/documents/data_sheet/HEF4511B.pdf
>
> A very common value in available circuits for the current limiting R is
> 470Ω, which gives ca 10 mA, but which would exceed the total current for
> the package. Even 220Ω is common, which indeed delivers 20 mA to one LED
> segment, but may fry the 4511 if you light 7 segments with 140 mA.
>
> How do you use the 4511?
>
> thanks
>
> rick
>
>
>
> _______________________________________________
> Synth-diy mailing list
> Synth-diy at dropmix.xs4all.nl
> http://dropmix.xs4all.nl/mailman/listinfo/synth-diy
>



More information about the Synth-diy mailing list