Hi there wonderful people,

I need to drive 10x low power LEDs (If = 1mA, Vf = 1.8V) in a defined, fixed sequence like this:



This LED sequence will be executed upon input from a MCU. Once the sequence is over, the MCU will put the IC/circuit into a low power state to conserve battery. I considered using a shift register but couldn't find any part that would go down to 1.8V operation and has output current in few mAs. Another option is to switch to an MCU with more GPIOs - this adds about $0.30 to BOM - but there's has to be better solution than such a brute force approach.

I would really appreciate if you can point me in a direction. I could take it from there.

Thanks

 

Welcome to AAC!

From my experience, I would go with a MCU with more IO. It may bump the incremental cost a bit but that cost will be offset by a likely smaller PCB overall, simpler assembly, and one (or more) fewer line items on the BOM.

A shift register could be used of course if you use it as a simple IO expander and generate the sequences in firmware.

Good luck!