Simple question: I am using the large digit driver breakout to manipulate two 6.5" 7 segment displays. I want to use the large digit driver to power much larger LED segments that consume 250mA. I don’t really want to have to build a transistor switching array to handle the load. I would need 16 of them plus resistors. Does Sparkfun have a breakout for a multi channel switcher for doing something like this?
Hi seb.
Unfortunately we don’t have a driver that has a higher current output. The Large Digit Driver has a max output of 250mA per segment, but you’d be running it at maximum capacity so it’s possible that might fry it or decrease it’s lifetime.
We do have a transistor array ([ULN2803) that shouldn’t be too hard to connect to the large digit driver to boost it’s output to 500mA per segment. Another option would be to skip the large digit driver and use two cascaded [74HC595’s that each have a ULN2803 on their output. You’d need to make a little board to set that up, but it would work and might be fun to assemble. :-)](Shift Register 8-Bit - SN74HC595 - COM-13699 - SparkFun Electronics)](Darlington Driver 8-Channel ULN2803 DIP - COM-00312 - SparkFun Electronics)
On the ULN2803, in addition to the 500mA per pin, there are limits on total current (2.5A) and temperature dissipation. http://www.ti.com/lit/ds/symlink/uln2803a.pdf is a newer and better datasheet for the part, and gives formulas for calculating the thermal limits. For the Large Digit displays, you are OK on the total current.
/mike
Forgive me, im new to using forums, am I okay to ask a new large digit Driver question here? If so, I would like to use 2 large digit drivers to operate 2 7 segment displays that i have made myself using store bought 5cm red led strips. These strips have inline resistors of their own so are ready to run straight from a 12v supply. Each strip is rated at 50ma, therefore 50ma per segment 350ma per display. The driver however is limited to 20ma per segment. Would it be harmful to the driver if I remove the resistors from the large digit drivers and replace them with a solid wire allowing the led strips to rely on their own inline resistors?
Thankyou.
Hi Micmac.
Normally you would want to start a new thread, but your question is similar to the original posters so it’s OK.
The resistors on the Large Digit Driver are pretty small in value so I don’t think it would matter much for your homemade display but if you jumper over them with wire, your display will get slightly brighter. I’ve used these on my own homemade 6 digit seven segment display built from 12 volt LED strips and it was plenty bright when I left the resistors in place.
I’d give it a try with an unmodified board first. It might work just fine and then you don’t need to worry about modifying the board at all. It would be OK to jumper them out of you needed to though. 
Amazing thankyou.