Designing a big seven-segment

Hello,
I need to design a big 4 channel 7segment for my project, I used to design one by myself in past, but it wasn't very pleasing to work, in fact, it was painful to work with.

In that design, I putted 7 lines of parallel LEDs on a piece of wood which holes for LED pins were cut out with a laser cut machine and then I used thin wires to connect the LEDs in the back of the board. the problem was that the multiplexing those 4 channels needed 12 pins of my Arduino, and I had lots of issues for driving the LED using transistors.

This time I want to make a PCB for that, and I'm my ideal design is to use a TM1637 IC to drive the segments because of the 2 pin connection.
I downloaded the IC datasheet and here's the electric characteristics:

Now I have a problem to find what I want from this datasheet, I need to know the maximum current each segment can draw from the IC, but I don't know which one of the given current limits is that.

Also, I want to know is there another way to do or another IC to use instead of the TM1637?

Datasheet_TM1637.pdf (688 KB)

MC14499 looks like a better bet. Much less complex (unless you want to scan a keypad as well). Drives up to 50mA/segment. Needs transistors to drive digits (one per digit) - datasheet gives details.

johndg:
MC14499 looks like a better bet. Much less complex (unless you want to scan a keypad as well). Drives up to 50mA/segment. Needs transistors to drive digits (one per digit) - datasheet gives details.

I guess 50mA is not enough, I don't actually remember how many LED were in each segment and I don't have access to the board now, but I guess it was 12 LEDs which draws 150mA in this connection:

bandicam 2020-12-09 20-01-21-393.jpg

bandicam 2020-12-09 20-01-21-393.jpg

Why don't use an addressable LED strips? Wiring is pretty easy and you need only one pin to control all 4 digits.

Setrik_aZ:
I guess 50mA is not enough

Think you’ll have to go with more transistors then (BTW TM1637 is also 50mA max per segment).

alesam:
Why don't use an addressable LED strips? Wiring is pretty easy and you need only one pin to control all 4 digits.

Actually, I wanted to, but I couldn't find the WS2812 or any other "good" addressable LED strips, those who I found were all low quality ones. and those strips are very expensive here for some reason(s), and also my application is to install this seven-segment in an industrial situation to be clearly visible form about 100 meters, so I putted those LED strips out of mind.
In my old design I used these kind of LEDs which we call them "Daylight LEDs" here, because they are pretty bright and visible in daylight, they're original usage is in those ugly LED signs which stores use.

johndg:
Think you'll have to go with more transistors then (BTW TM1637 is also 50mA max per segment).

Omg, How can I use transistors for it? I'm reaaaaallly bad at transistors, can you help me to design a circuit for it?

Is there a way to use ULN2003 or ULN28003?

And again I'd consider to use addressable IC (WS2811 NeoPixel LED Driver Chip - 10 Pack : ID 1378 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits) each chip can drive 3 LEDs with 18mA for each.

alesam:
And again I'd consider to use addressable IC (WS2811 NeoPixel LED Driver Chip - 10 Pack : ID 1378 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits) each chip can drive 3 LEDs with 18mA for each.

The link you gave is 404.

Forget about matrixing (chips) if you value brightness.
TPIC6B595 shift registers are commonly used for large 7-segment displays.
One per digit.
Has been done many times on this site. Do a search.
Leo..

I've fixed a link. And you can buy that chips cheaper from other sources. For example - https://www.amazon.com/Todiys-WS2811-Integrated-Circuit-WS2811S/dp/B084Q77W44

alesam:
I've fixed a link. And you can buy that chips cheaper from other sources. For example - Todiys New 20Pcs for WS2811 SOP-8 LED Driver Integrated Circuit IC Chip WS2811S: Amazon.com: Industrial & Scientific

What's the benefit in using these?

Setrik_aZ:
What's the benefit in using these?

Very simple wiring/pcb design. Only one pin required to drive all of them.

Though TPIC6B595 may be a better solution for your case

alesam:
Very simple wiring/pcb design. Only one pin required to drive all of them.

Oh yes I see, but I mean, I have to make 10 of these, each contains 340 LEDs (7*12 +4) , divided by 3, I'll need 114 ICs for each panel, 1140 for 10 panels :drooling_face: dude I don't look like a pick and place machine XD

Setrik_aZ:
Oh yes I see, but I mean, I have to make 10 of these, each contains 340 LEDs (7*12 +4) , divided by 3, I'll need 114 ICs for each panel, 1140 for 10 panels :drooling_face: dude I don't look like a pick and place machine XD

Based on you post #2 I thought you need a 2 IC per segment to drive 12 LEDs .

alesam:
Based on you post #2 I thought you need a 2 IC per segment to drive 12 LEDs .

No, each segment has 12 LEDs.

This time I want to make a PCB for that, and I'm my ideal design is to use a TM1637 IC to drive the segments because of the 2 pin connection.

you are aware that LED segments can be bought pre-made?

an Example in several sizes

Setrik_aZ:
Omg, How can I use transistors for it? I'm reaaaaallly bad at transistors, can you help me to design a circuit for it?

Is there a way to use ULN2003 or ULN28003?

Maybe - if we turn the way it operates upside down. The MC14499 is designed to drive common cathode displays, i.e. the segment outputs supply current to the (separate) anodes of the segment LEDs, and the digit selects pull the (commoned) cathodes of the selected digit down to (near) ground.

Darlington arrays like ULN2003 can only pull down, so say we use one to pull down the LED segment cathodes, then we just have to provide 4 high-side drivers to supply current to the common anodes of each digit. Can probably find a MOSFET that'll do the job. I'll have a look around.
Meanwhile, if anyone else would like to chip in, feel welcome.

Most 7-segment solutions use matrixing (switching between digits).
As said before...
Don't matrix large 7-segment displays that (assuming) will be used in bright (day)light.
Every doubling of digits halves average LED current.

TPIC6B595 chips can continuously sink 150mA per segment, and at a high voltage (large strings).
Leo..

Caveat: ULN 2003 etc. only pull down to about 1V, which only gives you 4V per segment. Have to knock off a little bit more for the high side driver, so you haven't got much to play with. Sounds a bit tight for 2 diodes in series. And with all segments on (8888) you're limited to about 180mA per segment to avoid frying the chip.

Edit: crossed with Wawa. His offering of a TPIC6B595 sounds like the best bet.