| ??? 06/22/07 14:31 Modified: 06/22/07 15:11 Read: times |
#141158 - I would wait 3.5µsec Responding to: ???'s previous message |
Chico said:
I'm using 10K pots For worst case charging time add all the stray capacitances and all source impedances. An assumed stray capacitance of CD4051 of about 50pF and an internal stray capacitance of ADC0804 of about 12pF gives 62pF. Maximum source impedance of 10k pot is 2k5Ohm, plus internal source resistance of ADC0804 of 5k gives 7.5kOhm. This results in a worst case charging time constant of 7.5kOhm x 62pF = 465nsec. Total charging needs about 5 x 465nsec = 2325nsec. (Take note, a sophisticated calculation of settling time of the actual two pole filter will yield a somewhat lower settling time.) The CD4051, on the other hand, shows a propagation delay time from address to signal output of up to 1000nsec. So, I would wait 3.5µsec. Kai |
| Topic | Author | Date |
| ADC0804 and analog mux 4051 help | 01/01/70 00:00 | |
| Source impedance driving the CD4051? | 01/01/70 00:00 | |
| what is "Source impedance driving"? | 01/01/70 00:00 | |
| Source impedance | 01/01/70 00:00 | |
| RC | 01/01/70 00:00 | |
| I'm using just 10K pots | 01/01/70 00:00 | |
| I would wait 3.5µsec | 01/01/70 00:00 | |
| Using a multiplexer | 01/01/70 00:00 | |
| Crosstalk/Interacting is the problem, need help | 01/01/70 00:00 | |
| Do you use buffers? | 01/01/70 00:00 | |
| No, just pots connected to inputs of 4051, my code | 01/01/70 00:00 | |
| Why add complexity? | 01/01/70 00:00 | |
To make it work?? | 01/01/70 00:00 |