JN516X Datasheet, PDF (20/94 Pages) NXP Semiconductors – IEEE802.15.4 Wireless Microcontroller

5.2.2 32kHz Crystal Oscillator
In order to obtain more accurate sleep periods, the JN516x contains the necessary on-chip components to build a
32kHz oscillator with the addition of an external 32.768kHz crystal and two tuning capacitors. The crystal should be
connected between 32KXTALIN and 32KXTALOUT (DIO9 and DIO10), with two equal capacitors to ground, one on
each pin. Due to the small size of the capacitors, it is important to keep the traces to the external components as
short as possible.
The electrical specification of the oscillator can be found in Section 19.3.9. The oscillator cell is flexible and can
operate with a range of commonly available 32.768kHz crystals with load capacitances from 6 to 12.5pF. However,
the maximum ESR of the crystal and the supply current are both functions of the actual crystal used, see Appendix
B.1 for more details.
32KXTALIN
JN516x
32KXTALOUT
Figure 9: 32kHz Crystal Oscillator Connections
5.2.3 32kHz External Clock
An externally supplied 32kHz reference clock on the 32KXTALIN input (DIO9) may be provided to the JN516x. This
would allow the 32kHz system clock to be sourced from a very stable external oscillator module, allowing more
accurate sleep cycle timings compared to the internal RC oscillator. (See Section 19.2.3)
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JN-DS-JN516x v1.1 Production
© NXP Laboratories UK 2013