Each LED needs to be one colour / the other colour or off. I may even=20 PWM the polarity to get a mix of the two. I just stumbled on the Microchip HV5308 which has 32 half bridges in a=20 PLCC package with a serial input. Each output can do 20mA and Vpp (output rail) can be 90V ! This would give me 16 outputs if I wanted. It's not stupidly expensive=20 either - about AUD $7.50 (1-off). I think it would be worth the money=20 to simplify the design. David... On 14/01/2017 8:49 AM, Brent Brown wrote: > To clarify, do you need to turn the LED off? E.g. for a red/green bicolor= LED are there 2 required states red/green, or 3 states: red/green/off? > Either way I probably don't have an answer :-) But I can appreciate it's = a tricky problem. Solution may need to be clever. > > -------- Original message -------- > From: "David Duffy (AVD)" > Date: 1/14/17 11:26 AM (GMT+12:00) > To: "Microcontroller discussion list - Public." > Subject: [EE] Shift Register 20mA Push-Pull Outputs > > I have an idea for a project that needs to drive 8 outputs for (remotely > mounted) 2-pin bi-colour LEDs. > > Since the LEDs are 2-pin, I'll need to reverse the polarity on them > individually. There may be 1 or 2 LEDs on each output, so if they were > in series that means I need a swing of more than 5V. > > I was thinking of two shift registers arranged as 8 H-bridges, but can't > seem to find any that have a Vdd of more than 5V and have an output > current of more than a couple of mA. > > There are H-bridges out there, but the cost and space adds up pretty > quickly for 8 outputs. Ideally I'd like nothing finer pitch than a SOIC > package. > > Any ideas? --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .