Thank you for that - I was looking at the HV513 which is push-pull and is rated for the higher voltage levels.
Being push pull - can I use those for the High side AND the low side? - Richard On Thursday, 20 May 2021 at 16:02:47 UTC+1 Paul Andrews wrote: > The HV5622 has open drain outputs, so the cathodes will be left to > gradually float to whatever value they feel like. They probably won't do > this fast enough to prevent ghosting and you don't really want them to > float in a multiplexed clock anyway. I would suggest a push-pull chip for > the cathodes, like the HV9808. > > On Thursday, May 20, 2021 at 1:06:54 AM UTC-4 gregebert wrote: > >> For my current clock project, I have a 9-segment / 13-character display >> that must be multiplexed, so I use a 4:16 decoder to drive PMOS >> anode-transistors on the high-side. The 4 bits into the DeMUX are piped >> thru digital isolators (SI8710), and driven from the FPGA. I use an >> isolated DCDC converter to provide a negative 12V supply relative to the >> anode supply (about 200V, because it's unregulated). >> >> The low-side for the cathodes are just NPN current-limiters, also driven >> by the FPGA. >> >> >> [image: ScreenHunter_32 May. 19 22.00.jpg] >> On Wednesday, May 19, 2021 at 9:21:49 PM UTC-7 Richard Scales wrote: >> >>> I am trying to learn about multiplexed displays (I thought it was about >>> time I had a go at this) and I believe that I understand the basics - in >>> as much as it requires the switching of the required anode as well as the >>> required cathode (all of which are wired in parallel). >>> >>> I understand that I can use something as simple as a single transistor >>> for the cathode (low side) and a couple of transistors for the anode (high >>> side). >>> >>> Again, for the low side driver I could use any of the 'standard' shift >>> register type drivers that we use in clocks such as an HV5622 (I appreciate >>> that's way too many bits and I'm sure that there will be a smaller >>> equivalent part available. >>> >>> Specifically - is there such a part that I could use for the high side, >>> ie switching the HV to the relevant anode? >>> >>> I know that I could use a simple shift register (74595 for example) plus >>> the transistors for a high side switch, I just wonder if there is a part >>> which does all that in one package? >>> >>> All pointers gleefully received. >>> >>> - Richard >>> >>> >>> -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b989d1b1-dbe3-4b39-a019-54fdacad024cn%40googlegroups.com.
