fpga driving multiple leds, high amp concerns

[aussie_laser_dude]

Hi everyone,
this is my first forum post, hoping to enjoy my time reading through the forums

Can a DE0 nano FPGA evaluation board (a cyclone IV fpga) drive 16 standard LEDS (just the kind of common LEDS you get in hobbyist packs). I'm concerned that trying to light them all up at once could damage my fpga due to all the current passing through it. I'm unsure on how much current the fpga can handle?

I've just discovered fpgas, pretty blown away by the stuff they can do!
cheers

[TheHolyHorse]

You should be able to find that information in the datasheet of the fpga.

Also in what configuration will the LEDs be in? Series, parallel?

Series will result in lower current but higher voltage (the forward voltage if the LEDs added together) which is probably gonna be way higher than the fpga can output.

The best solution is to get some external led driving circuitry.

[rstofer]

Table 1.15 shows a value of +-4 mA for pin current: https://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/hb/cyclone-iv/cyiv-53001.pdf

Digilent tends to use transistors to drive the LEDs - see page 2
https://reference.digilentinc.com/_media/reference/programmable-logic/arty-a7/arty_a7_sch.pdf

[Jan Audio]

Or use higher resistors to keep it low current ( and less bright )

[TheHolyHorse]

Or use higher resistors to keep it low current ( and less bright )

He still needs the higher voltage. 4mA is enough to make the LEDs emit light, but if he connects them in series he's still gonna need like 32V assuming that the LEDs have a 2V forward voltage.

[aussie_laser_dude]

Thanks everyone. Table 1-15 for cyclone IV link given by rstofer saying +-4mA is what I was after. Looks like it'll handle 16 low power (<2ma) leds on 16 different I/O pins with no problem. Transistors are a nice idea if I need more power.

Thanks again guys 

[mikerj]

Thanks everyone. Table 1-15 for cyclone IV link given by rstofer saying +-4mA is what I was after. Looks like it'll handle 16 low power (<2ma) leds on 16 different I/O pins with no problem. Transistors are a nice idea if I need more power.

Thanks again guys 

That is absolutely fine, I think many people were thinking you wanted to drive all those LEDs from one pin which wouldn't work well.

[TheHolyHorse]

Thanks everyone. Table 1-15 for cyclone IV link given by rstofer saying +-4mA is what I was after. Looks like it'll handle 16 low power (<2ma) leds on 16 different I/O pins with no problem. Transistors are a nice idea if I need more power.

Thanks again guys 

I haven't read the datasheet but check the total allowed IO current. Just because max IO pin current is 4mA doesn't mean you can do that on to many pins at the same time.

Be sure to check that before you accidentally toast a chip.