Best way to power 'Tiered' LED's?

Spere

As part of a larger project, I need to drive a module (lcd display) with 3 common cathode LED's (only one being on at a time). Whenever any of the three is on, another set of 4 parallel LED's will also be lit.

This uses 3 pins on the stamp and each pin has a high sided pnp to drive the 100ma of LED's. I'd appreciate the groups feedback on this. Is their a reasonable, better, more robust way of doing this? Ideally, without drastically increasing the complexity.

Here is the circuit:
VBIRC - LED Driver Subsystem - v1.2.pdf


Here is an online simulator of the circuit.
http://tinyurl.com/k4a7e7o
Note: The falstad.com simulator uses java and the window will likely need to be enlarged/maximized.

Thanks!

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Version:
1.2 - added a resistor for each discrete LED
1.1 - VBIRC - LED Driver Subsystem - v1.1.pdf

Phil Pilgrim (PhiPi)

One thing to note: in your paralleled LED circuit, each LED should have its own series resistor. Otherwise, slight differences in forward voltage will cause them to light with different intensities. Some may not light at all.

-Phil

Spere

Phil Pilgrim (PhiPi) wrote: »

One thing to note: in your paralleled LED circuit, each LED should have its own series resistor. Otherwise, slight differences in forward voltage will cause them to light with different intensities. Some may not light at all.

-Phil

Thank you for the note Phil, I updated the drawings and the original post.