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Q&A LED with a parallel resistor

It is common to have a series resistor to limit the current trough an LED. I saw a circuit using the LED driver: stp16cpc26. but instead having the series resistor, they are in parallel. This LED...

1 answer  ·  posted 4y ago by zeke‭  ·  edited 1y ago by Lorenzo Donati‭

Question LED-driver
#3: Post edited by user avatar Lorenzo Donati‭ · 2023-08-09T19:52:20Z (over 1 year ago)
Retagged.
LED-driver
#2: Post edited by user avatar zeke‭ · 2020-08-28T21:02:46Z (about 4 years ago)
Updating schematic to provide more background
  • ![Image alt text](https://electrical.codidact.com/uploads/zz4M9zvS8HR7cWnWiuQq4wF5)LED with parallel resistor
  • It is common to have a series resistor to limit the current trough an LED.
  • I saw a circuit using the LED driver: stp16cpc26. but instead having the series resistor, they are in parallel.
  • This LED driver is a kind of constant current source, where you select the current selecting the Rext.
  • Sorry but honestly I can understand why in parallel... I meant It seems having the series resistor might work as well
  • ![Uploading, please wait...]()
  • It is common to have a series resistor to limit the current trough an LED.
  • I saw a circuit using the LED driver: stp16cpc26. but instead having the series resistor, they are in parallel.
  • This LED driver is a kind of constant current source, where you select the current selecting the Rext.
  • Sorry but honestly I can understand why in parallel... I meant It seems having the series resistor might work as well
  • ----- Edit----
  • Picture updated
  • This is a LED driver, current output is set by the Rext.
  • This is a SPI (kind of 16 bit shift register) and the brightness is controlled by the PWM duty cycle. I do not understand why the resistors are in parallel instead of series.
  • This is a professional design
  • ![Image alt text](https://electrical.codidact.com/uploads/rBLvCvWhK18XUp84e74EjCqT)
#1: Initial revision by user avatar zeke‭ · 2020-08-28T17:45:30Z (about 4 years ago) 
LED with a parallel resistor
![Image alt text](https://electrical.codidact.com/uploads/zz4M9zvS8HR7cWnWiuQq4wF5)LED with parallel resistor

It is common to have a series resistor to limit the current trough an LED.
I saw a circuit using the LED driver: stp16cpc26. but instead having the series resistor, they are in parallel.

This LED driver is a kind of constant current source, where you select the current selecting the Rext.

Sorry but honestly I can understand why in parallel... I meant It seems having the series resistor might work as well

![Uploading, please wait...]()