| ??? 11/16/06 02:07 Read: times |
#128059 - Looks like having the wrong burden caps Responding to: ???'s previous message |
Gopal said:
Is it related to any capacitor (especially the 232 capacitors)? What do you mean by "232"?? Are you sure the burden caps are 33pF NP0 ceramics?? Gopal said:
What should be the correct value for load capacitance for crystals? Crystals don't need a certain capacitance. The Pierce oscillator of your micro does need it, to guarantee a total phase shift of 180° by introducing a phase lag by the help of burden caps. We have discussed this a bit here: http://www.8052.com/forum/read.phtml?id=79811 When a crystal manufacturer specifies a capacitance, then it's meant, that the least deviation from stamped on frequency is gained, when having this burden capacitance at the oscillator. Unfortunately, Philips does not specify the proper burden capacitance in their datasheet. In such a case the best guess is, that the oscillator works like the original one from Intel. And this one needs about 33pF each. Kai |
| Topic | Author | Date |
| Crystal oscillations stop in P89C51RD2 | 01/01/70 00:00 | |
| PCB or flying wires? | 01/01/70 00:00 | |
| Looks like having the wrong burden caps | 01/01/70 00:00 | |
| correct, but | 01/01/70 00:00 | |
| Couldn't find the user manual... | 01/01/70 00:00 | |
| neither can I | 01/01/70 00:00 | |
| Try this... | 01/01/70 00:00 | |
| Suspect the board | 01/01/70 00:00 | |
| Wrong! | 01/01/70 00:00 | |
| Xtal pdf for Microcontrollers | 01/01/70 00:00 | |
SST Xtal - Micro Application note | 01/01/70 00:00 |