JN5148 NXP Semiconductors, JN5148 Datasheet - Page 90

• Manufacturer Part Number: JN5148
• Description: The JN5148 is an ultra low power, high performance MCU combined with an IEEE802
• Manufacturer: NXP Semiconductors

B.2 32MHz Oscillator
The JN5148 contains the necessary on-chip components to build a 32 MHz reference oscillator with the addition of
an external crystal resonator, two tuning capacitors. The schematic of these components are shown in Figure 57.
The two capacitors, C1 and C2, will typically be 15pF ±5% and use a COG dielectric. For a detailed specification of
the crystal required and factors affecting C1 and C2 see Appendix B.1. As with all crystal oscillators the PCB layout is
especially important, both to keep parasitic capacitors to a minimum and to reduce the possibility of PCB noise being
coupled into the oscillator.
The clock generated by this oscillator provides the reference for most of the JN5148 subsystems, including the
transceiver, processor, memory and digital and analogue peripherals.
32MHz Crystal Requirements
90
Crystal Frequency
Crystal Tolerance
Crystal ESR Range (Rm)
Crystal Load Capacitance
Range (CL)
Recommended Crystal
External Capacitors (C1 & C2)
For recommended Crystal
Parameter
Not all Combinations of Crystal Load Capacitance and ESR are Valid
XTALIN
Figure 58: Crystal oscillator connections
Load Capacitance 9pF and max ESR 40 Ω
10Ω
Min
6pF
JN-DS-JN5148-001 1v7
C1
R1
32MHz
15pF
Typ
9pF
C2
XTALOUT
JN5148
40ppm
12pF
Max
60Ω
© NXP Laboratories UK 2011
Including temperature
and ageing
See below for more
details
See below for more
details
CL = 9pF, total external
capacitance needs to be
2*CL. , allowing for stray
capacitance from chip,
package and PCB
Notes