| ??? 10/16/05 09:15 Read: times |
#102463 - manufacturing tolerances Responding to: ???'s previous message |
The crystal is a electromechanical device, and its fundamental resonant frequency depends mainly on its mechanical size. The megahertz oscillators are very small so it's not too easy (read: more expensive if possible at all) to manufacture them to the same tight tolerances as the kilohertz oscillators, which are simply bigger.
That's all. (OK it's far more complicated and one there are also temperature dependences and aging...) Usually, for precise timing of a system which has to have high performance (fast clock), either two oscillators are used, or an external dedicated RTC is used (the most common solution probably), or some microcontrollers have PLL which can run high output clocks from the 32.768kHz oscillator. Please correct me if I am wrong. Jan Waclawek |
| Topic | Author | Date |
| Software Based RTC | 01/01/70 00:00 | |
| Context | 01/01/70 00:00 | |
| Link to my RTC - sftware crystal freq. | 01/01/70 00:00 | |
| The precision is depending on the fracti | 01/01/70 00:00 | |
| How to count seconds | 01/01/70 00:00 | |
| How to decide count for a 3.5795Mhz, | 01/01/70 00:00 | |
| the frequency range does not matter | 01/01/70 00:00 | |
| the "tricks" | 01/01/70 00:00 | |
| 3.93216MHz is better | 01/01/70 00:00 | |
| 4.915200 | 01/01/70 00:00 | |
| 3.93216 ?? | 01/01/70 00:00 | |
| 3.93216 is standard frequency | 01/01/70 00:00 | |
| Can i have some clarifications on XTALS | 01/01/70 00:00 | |
| manufacturing tolerances | 01/01/70 00:00 | |
| low frequencies Crystals are bigger ? | 01/01/70 00:00 | |
| 32.768kHz means low current consumption | 01/01/70 00:00 | |
| so higher Frequeny crystals are accurate | 01/01/70 00:00 | |
Yes! | 01/01/70 00:00 | |
| The Right Frequency | 01/01/70 00:00 |