User Manual
Table Of Contents
- 1 Introduction
- 2 Pin Configurations
- 3 CPU
- 4 Memory Organisation
- 5 System Clocks
- 6 Reset
- 7 Interrupt System
- 8 Wireless Transceiver
- 9 Digital Input/Output
- 10 Serial Peripheral Interface
- 11 Timers
- 12 Pulse Counters
- 13 Serial Communications
- 14 JTAG Debug Interface
- 15 Two-Wire Serial Interface
- 16 Four-Wire Digital Audio Interface
- 17 Random Number Generator
- 18 Sample FIFO
- 19 Intelligent Peripheral Interface
- 20 Analogue Peripherals
- 21 Power Management and Sleep Modes
- 22 Electrical Characteristics
- 22.1 Maximum Ratings
- 22.2 DC Electrical Characteristics
- 22.3 AC Characteristics
- 22.3.1 Reset and Voltage Brown-Out
- 22.3.2 SPI MasterTiming
- 22.3.3 Intelligent Peripheral (SPI Slave) Timing
- 22.3.4 Two-wire Serial Interface
- 22.3.5 Four-Wire Digital Audio Interface
- 22.3.6 Wakeup and Boot Load Timings
- 22.3.7 Bandgap Reference
- 22.3.8 Analogue to Digital Converters
- 22.3.9 Digital to Analogue Converters
- 22.3.10 Comparators
- 22.3.11 32kHz RC Oscillator
- 22.3.12 32kHz Crystal Oscillator
- 22.3.13 32MHz Crystal Oscillator
- 22.3.14 24MHz RC Oscillator
- 22.3.15 Temperature Sensor
- 22.3.16 Radio Transceiver
- Appendix A Mechanical and Ordering Information
- Appendix B Development Support
Jennic
© Jennic 2009 JN-DS-JN5148-001 1v2 91
Preliminary
Three examples of typical crystals are given, each with the value of external capacitors to use, plus the likely supply
current and start-up time that can be expected. Also given is the maximum recommended ESR based on the start-up
criteria given in Appendix
B.1.3. The values of the external capacitors can be calculated using the equation in
Appendix
B.1.2 .
Load Capacitance Ext Capacitors Current Start-up Time Max ESR
9pF 15pF 1.6uA 0.8Sec
70KΩ
6pF 9pF 1.4uA 0.6sec
80KΩ
12.5pF 22pF 2.4uA 1.1sec
35KΩ
Below is measurement data showing the variation of the crystal oscillator supply current with voltage and with crystal
ESR, for two load capacitances.
32KHz Crystal Oscillator Current
0.6
0.8
1
1.2
1.4
1.6
2.2 2.4 2.6 2.8 3 3.2 3.4 3.6
Supply Voltage (VDD)
Normalised Current (IDD)
32KHz Crystal Oscillator Current
0.6
0.8
1
1.2
1.4
1.6
10 20 30 40 50 60 70 80
Crystal ESR (K ohm)
Normalised Current (IDD)
9pF
12.5pF