How can I best drive and switch high side power (for multiplexing) between the 7 displays with as few components as possible, for under $2. I am trying to simplify a design.
I have a custom board design with seven common anode 7-segment displays. I plan to build a large amount of them where I want to minimize components as well as keep component costs down.
Currently, on the high side, I use a SN74HC595 to switch power between 7 IMD10AT108 (combined NPN/PNP on 1 chip) drivers which power the displays.
One IMD10AT108 (NPN/PNP driver) powers each display. That makes 8 components to drive the high side of 7 displays. I'm not satisfied with this, although it works great. For comparison, I'm able to handle to low side of all 7 displays with only 2 components...chip + resistor.
It seems "odd" that I can't find a single chip shift register style solution to this at low cost, like is quite easy to do on the low side via a number of different chips and methods. (Yes, I see $5 chips (qty 100) are available do to this.)
I'd be happy to switch over to common cathode if that made a solution available. I am also looking to stay with something that can be driven via shift register logic, because these board chain together to add more displays in a chain.
This seems to be a question that has been asked in a number of forums, and is a common design problem for people trying to drive a number of multiplexed 7-segment displays.
A PNP array chip seems like the easy answer, until you start looking and find out they don't exist. To me, this seems like a common problem without a simple (cheap) answer.
Since the design is about to be finalized, I'm making one last ditch effort to find an alternative. Thanks for any input.