| ??? 04/03/12 13:40 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#186989 - What I would do... Responding to: ???'s previous message |
Andy said:
What about the NXP improvement, the 74HCT9046? Doesn't have the dead-band in the middle like the 4046. I don't know the 9046, so I cannot say anything useful to this chip. If I were Mahmood I would use "phase comparator II" in his application. I wouldn't use ac coupling with a cap but directly couple the signal to pin 14. To make this realibly work I would use sharp signal edges AND center the signal arround Vcc/2 AND avoid rail to rail signals at pin 14. So, I would insert a circuit like shown in the lower part of Bild 8 in this link http://www.elektronik-kompendium.de/public/sc...ll4046.htm The driver need not to be a LMC555, of course, any CMOS inverter with push pull output stage will work, provided the 4046, this CMOS inverter and the triple-R-array see the same supply voltage. Final comment: The signal at pin 14 need not to have 50% duty cycle at all. Nearly any duty cycle will work. Kai Klaas |
