[ell-i-developers] "LeBulli" Led shield for PoElli

  • From: otso@xxxxxxxxxxxx
  • To: ell-i-developers@xxxxxxxxxxxxx
  • Date: Thu, 19 Jun 2014 15:31:16 +0300

Hi all,

I'm doing a schematic for a high power led driver shield for Ellduino, it
resembles a bit the schematic we have for hackathon. PDF attached.

Led to be driven is
https://www.gme.sk/img/cache/doc/518/177/vykonova-led-getian-gt-p6prgb4303-datasheet-1.pdf
or electrical equivalent.

Since selected LED has low forward voltage, buck topology is used.

Design has following assumptions, please correct me if I'm wrong:

1) 1 A of current can be drawn from 5V pin, which comes from PoE SMPS.

2) Device can receive and transmit information through ethernet port

3) There are 3 open-drain PWM  pins available.

4) Core can run at 48 MHz, so 8-bit PWM can be run at 48 MHz / 2^8 = 187,5
kHz

5) Pinout of Ellduino is correct (please check this if nothing else)

I'd also appreciate recommendations for pins to use for PWM. Open-drain
ability is a plus but not necessary. Even better would be to have phase
difference between PWM-signals to avoid unnecessarily high ripple current
on 5V pin.

Do you think I should add power arbiteration from Vin pin of Arduino Mega
for Arduino-friendliness? OTOH, Arduino Mega cannot reach required PWM
frequencies, so using a lot larger chokes and capacitors would be
required.

BR,
otso



Attachment: LeBulli.pdf
Description: Adobe PDF document

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