Read: 2377 times
|#138133 - The 4013 needs steep edges|
Responding to: Bruce Grenade's previous message
the "4013" needs steep edges at its clock input, otherwise the outputs can be become undefined! So, I would recommend the following circuitry:
Using an additional "40106" also allows you to spend the SET input of "4013" a proper level shifter. Just fabricate by the help of NPN a suited /FORCEON signal. As long as the micro gets no power, the NPN will be turned-off and by this the SET input of "4013" will be low. To force an "on" the micro must turn-on the NPN.
The circuit works as follows:
When pushing the switch, the 220nF cap is quickly discharged and the output of left "40106" goes high. When releasing the switch afterwards, the cap becomes charged again, but at a much lower speed. So, this part of circuit provides a reliable debouncing and guarantees steep edges at the CLK input.
A full analysis of this debouncing scheme can be found here.
- The parts at RES input of "4013" provides a power-on reset, which might be useful after changing the battery. Omit it if you don't need it.
- The 10k resistor limits the current through your silicon rubber switch.
- The two 1k5 resistors limit the input currents, if Vbat is accidentally shorted (during battery change or removal).
- The "40106" and "4013" are powered by Vbat, of course.
Some hints on the output cap of LP2992. Use a 10µF/6.3V Y5V cap like the one here.
As you can see from the impedance plot
this cap fullfills the ESR requirements of your regulator! "Better" ceramics are worse here!!!
Isolate the succeeding decoupling caps (at the micro, for instance) by the help of 1R resistors, so that the low ESR of these decoupling caps will not violate the ESR requirements of LP2992 again through the back-door.
|Momentary toggle soft switch with flip-flop?||Bruce Grenade||04/26/07 17:36|
|I don't like it.||Lynn Reed||04/26/07 19:58|
|How Bouncy||Bruce Grenade||04/27/07 06:52|
|what good does 'minimum' do you||Erik Malund||04/27/07 08:31|
|Schmidt trigger||Joseph Hebert||04/26/07 20:19|
|Tricky...||Sasha Jevtic||04/26/07 23:52|
|rail to rail bounce||Joseph Hebert||04/27/07 07:05|
|McKinney||Bruce Grenade||04/27/07 06:53|
|4013 FF toggle circuit||Charles Bannister||04/26/07 22:38|
|Values?||Bruce Grenade||04/27/07 06:55|
|Values of R1,R2 &R3? Look at PCB!||Charles Bannister||04/27/07 11:17|
|clocking a FF from an RC?||Andy Neil||04/27/07 11:51|
|Agreed||Bruce Grenade||04/29/07 13:45|
|Follow the datsheet, that is design||Erik Malund||04/30/07 06:20|
|Why dismissing the flip-flop?||Kai Klaas||04/30/07 07:02|
|dismissing the flip-flop?||Erik Malund||04/30/07 07:47|
|The CD4013 of Bruce's schematic||Kai Klaas||04/30/07 07:57|
|The CD4013 of Bruce's schematic is shown as a f/f||Erik Malund||04/30/07 08:40|
|I answered to Bruce...||Kai Klaas||04/30/07 09:07|
|The circuit shown,,,,||Michael Karas||05/02/07 05:52|
|Power Consumption||Bruce Grenade||05/02/07 14:08|
|Overlooking the obvious?||Sasha Jevtic||04/26/07 23:44|
|Simpler?||Andy Neil||04/27/07 00:24|
|Keymat||Andy Neil||04/27/07 09:16|
|Why not a hard switch?||Andy Neil||04/27/07 00:19|
|Requirements||Andy Neil||04/27/07 02:44|
|Industrial designers is why||Bruce Grenade||04/27/07 06:57|
|Fair enough!||Andy Neil||04/27/07 08:36|
|Let The Microconroller Decide||Michael Karas||04/27/07 03:27|
|dedicated microcontroller :-)||Jan Waclawek||04/27/07 05:11|
|Interresting no flip-flop||Bruce Grenade||04/27/07 07:04|
|dat is de bounce||Erik Malund||04/27/07 06:12|
|The 4013 needs steep edges||Kai Klaas||04/27/07 11:15|
|caps||Bruce Grenade||05/02/07 14:24|
|A Vauge Suggestion||Neil Kurzman||05/02/07 19:35|
|additional parts||Stefan Kanev||05/02/07 05:52|
|what pin of which chip in what package?||Erik Malund||05/02/07 06:35|
|chip on drawing in generic post||Stefan Kanev||05/02/07 06:44|
|slowig down the bugger is not going to make it clo||Erik Malund||05/02/07 07:46|
|What about this?||Bruce Grenade||05/02/07 14:17|
|what is 'SOFTSW"?||Erik Malund||05/02/07 15:49|
|Seems OK Except...||Michael Karas||05/02/07 16:01|
|nice to find a fellow "drawer of fuctions"||Erik Malund||05/02/07 16:05|
|I find it eaasier to just...||Michael Karas||05/02/07 16:14|
|We appreciate it||Bruce Grenade||05/03/07 18:27|
|Further Analysis....||Michael Karas||05/02/07 16:10|
|Would this work?||Kai Klaas||05/03/07 16:20|
|All comments noted||Bruce Grenade||05/03/07 17:20|
|Round 3 - Hopefully better||Bruce Grenade||05/03/07 20:40|
|Round 4 is the winner||Tomas Stein||05/04/07 11:10|
|Tomas?? Bruce?? Are you a schizo?||Kai Klaas||05/04/07 17:00|
|haha, yes||Bruce Grenade||05/05/07 00:03|
|A bit confusing...||Kai Klaas||05/05/07 08:46|