[Noisebridge-discuss] 3.3v serial-parallel shift register with open-collector output?

Anders Nelson anders.k.nelson at gmail.com
Wed Jun 20 19:57:39 UTC 2012


Heyoo,

I've become rather exasperated in my search for an 8-bit serial-parallel
shift register with open collector outputs. See, I'm trying to switch the
gates of some P-FETs that act as high-side current switches for the rows in
a scanned LED matrix. The LED bus voltage is 4.2v and all the ICs run on
3.3v.

I found the SN74LS596, but it's an ancient part that is not only enormous
but runs at 4.5v-5.5v which won't work in my system.

I could use a microcontroller and just toggle the tri-state status of the
pins but I worry about how fast the device will respond - It will have to
blast out the I/O change within a blanking cycle lasting 250ns. That
requires between 4 and 8 MIPS which is not too powerful but this is a
low-cost product. =/

Any suggestions are most appreciated!
--
Anders Nelson

+1 (517) 775-6129

www.erogear.com
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