Author Topic: LED Display Driver w/o Resistors & LED Display Longevity  (Read 228 times)

0 Members and 1 Guest are viewing this topic.

Offline Infrared_Fred

  • Contributor
  • Posts: 11
  • Country: us
LED Display Driver w/o Resistors & LED Display Longevity
« on: October 30, 2020, 02:48:56 pm »
Hello!      This is a repost from a different forum where I was suggested to post here.     
"I have this circuit in consideration for a LED display project and I was wondering if a circuit like this would be likely to reduce the longevity of the LED's lifespan, assuming the PWM frequency is high enough to not exceed the thermal mass of the LED and overheat it directly with high peak currents. Attached is the schematic in .pdf format.  As the schematic generally suggest I have not ironed out every circuit detail, nor am I necessarily definite on a single specific circuit element."   

Any thoughts on the circuit is welcome.

Thanks for any help!
https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/196/v.1.0-ULN2003-74HC04-TLC555-PWM-LED-Display-Driver.pdff
 

Offline TomS_

  • Frequent Contributor
  • **
  • Posts: 555
  • Country: gb
Re: LED Display Driver w/o Resistors & LED Display Longevity
« Reply #1 on: October 30, 2020, 08:38:11 pm »
Is something like a TLC5916 LED driver out of the question? It only requires 1 resistor to set the current for all of its channels.
 

Offline Infrared_Fred

  • Contributor
  • Posts: 11
  • Country: us
Re: LED Display Driver w/o Resistors & LED Display Longevity
« Reply #2 on: October 30, 2020, 10:51:54 pm »
I could use the TLC5916 for microcontroller projects (it has a serial input), but I am mainly interested in building this circuit because it is simple for non-microcontroller input a.k.a. counters, and I already have all the parts on hand. 
 

Online S. Petrukhin

  • Frequent Contributor
  • **
  • Posts: 780
  • Country: ru
Re: LED Display Driver w/o Resistors & LED Display Longevity
« Reply #3 on: November 02, 2020, 03:24:01 am »
You are using the wrong solution. Different numbers will light up with different brightness because several segments will be turned on simultaneously in parralel. You must limit the current of each segment separately. To do this, it is enough to use conventional current-limiting resistors and this indicator will please even your granddaughters.

 If you don't like resistors, you can use special current limiters for LEDs: NSI50005YT1G, NSI50010YT1G.
And sorry for my English.
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf