FS781/82/84
Crystal is 20 MHz is 1st Order with 18 pF load capacitance.
If Crystal load capacitance is different than 18 pF, C1 and C2 must be
For third overtone crystals, a parallel or series resonant trap is required.
Mount loop filter components as close to LF pin as possible.
C2 |
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| 1 | Xin | VDD | 8 |
| 20 MHz |
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27 pF |
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Y1 |
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C3 | 2 | Xout | S0 | 7 |
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27 pF |
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| FS781 |
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| 3 | S1 | FSOUT | 6 |
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| 4 | LF | VSS | 5 |
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| R6 |
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C7 | C8 |
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**
**Occasionally, C8 is used to create a second pole for this loop filter. Refer to Loop Filter Selection
table. .
C1 | VDD |
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| 0.1 uF |
FSOUT
Figure 5. FS781 Schematic
Document #: | Page 7 of 12 |
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