Thanks, David. I used the 560R resistors to drop the supply voltage from 12v to 1.8v but I missed that the MM5316 outputs only 1.5 mA. It provides enough current to drive VFDs but it’s way too low to comfortably drive the LEDs. Interestingly though, I had only connected the minutes LED to the chip and the LED seemed happy and the chip stayed cool. But evidently (I surmise) l the excessive current draw by the LED segments was messing up the internal timing of the chip.
Randy > On May 16, 2025, at 12:18 PM, David <[email protected]> wrote: > > The MM5316 datasheet doesn’t say that this part is capable of driving LEDs. > It is too high voltage and too low current capability. Use some other chip > for that. > > David Forbes, Tucson AZ > >> On May 16, 2025, at 6:53 AM, [email protected] wrote: >> >> Hi all, >> I’m experiencing a strange timing problem when using an MM5316 clock chip to >> drive a 7-segment LED display. The clock chip drives non-multiplexed >> individual segments for each of the four digits for minutes, 10 minutes, >> hours, and 10 hours, and it is designed to drive VFDs directly. It works >> fine when I set it up to drive IV-12 VFDs. I’m powering the chip with about >> 12 vdc. But when I connect a 7-segment LED display to it using 560R voltage >> dropping resistors to each segment, the minutes digit advances every 30 >> seconds rather than 60 seconds. >> >> Anyone have any thoughts on what might be causing this to happen? >> >> TIA, >> Randy >> >> >> Sent from my iPhone >> >> -- >> 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, visit >> https://groups.google.com/d/msgid/neonixie-l/0D6422E0-9492-495D-8692-D96E680B0AE6%40gmail.com. > > -- > 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, visit > https://groups.google.com/d/msgid/neonixie-l/81EF9844-5383-487A-A487-14272027B259%40gmail.com. -- 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, visit https://groups.google.com/d/msgid/neonixie-l/E25017D4-DDDF-4A3C-9228-E916CFDF7597%40gmail.com.
