JN516X Datasheet, PDF (86/94 Pages) NXP Semiconductors – IEEE802.15.4 Wireless Microcontroller

As is stated above, not all combinations of crystal load capacitance and ESR are valid, and as explained in Appendix
B.1.3 there is a trade-off that exists between the load capacitance and crystal ESR to achieve reliable performance.
For this reason, we recommend that for a 9pF load capacitance crystals be specified with a maximum ESR of 40
ohms. For lower load capacitances the recommended maximum ESR rises, for example, CL=7pF the max ESR is 61
ohms. For the lower cost crystals in the large HC49 package, a load capacitance of 9 or 10pF is widely available and
the max ESR of 30 ohms specified by many manufacturers is acceptable. Also available in this package style, are
crystals with a load capacitance of 12pF, but in this case the max ESR required is 25 ohms or better.
Below is measurement data showing the variation of the crystal oscillator amplifier transconductance with
temperature and supply voltage, notice how small the variation is. Circuit techniques have been used to apply
compensation, such that the user need only design for nominal conditions.
4.35
4.3
4.25
4.2
4.15
4.1
-40
-20
32MHz Crystal Oscillator
0
20
40
60
Temperature (C)
80
100
32MHz Crystal Oscillator
4.31
4.3
4.29
4.28
2
2.2
2.4
2.6
2.8
3
Supply Voltage (VDD)
3.2
3.4
3.6
86
JN-DS-JN516x v1.1 Production
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