SWRS046I November   2006  – September 2018 CC1020

PRODUCTION DATA.  

  1. 1Device Overview
    1. 1.1 Features
    2. 1.2 Applications
    3. 1.3 Description
    4. 1.4 Functional Block Diagram
  2. 2Revision History
  3. 3Terminal Configuration and Functions
    1. 3.1 Pin Diagram
    2. 3.2 Pin Configuration
  4. 4Specifications
    1. 4.1  Absolute Maximum Ratings
    2. 4.2  ESD Ratings
    3. 4.3  Recommended Operating Conditions
    4. 4.4  RF Transmit
    5. 4.5  RF Receive
    6. 4.6  RSSI / Carrier Sense
    7. 4.7  Intermediate Frequency (IF)
    8. 4.8  Crystal Oscillator
    9. 4.9  Frequency Synthesizer
    10. 4.10 Digital Inputs and Outputs
    11. 4.11 Current Consumption
    12. 4.12 Thermal Resistance Characteristics for VQFNP Package
  5. 5Detailed Description
    1. 5.1  Overview
    2. 5.2  Functional Block Diagram
    3. 5.3  Configuration Overview
      1. 5.3.1 Configuration Software
    4. 5.4  Microcontroller Interface
      1. 5.4.1 Configuration Interface
      2. 5.4.2 Signal Interface
      3. 5.4.3 PLL Lock Signal
    5. 5.5  4-wire Serial Configuration Interface
    6. 5.6  Signal Interface
      1. 5.6.1 Synchronous NRZ Mode
      2. 5.6.2 Transparent Asynchronous UART Mode
      3. 5.6.3 Synchronous Manchester Encoded Mode
        1. 5.6.3.1 Manchester Encoding and Decoding
    7. 5.7  Data Rate Programming
    8. 5.8  Frequency Programming
      1. 5.8.1 Dithering
    9. 5.9  Receiver
      1. 5.9.1  IF Frequency
      2. 5.9.2  Receiver Channel Filter Bandwidth
      3. 5.9.3  Demodulator, Bit Synchronizer, and Data Decision
      4. 5.9.4  Receiver Sensitivity Versus Data Rate and Frequency Separation
      5. 5.9.5  RSSI
      6. 5.9.6  Image Rejection Calibration
      7. 5.9.7  Blocking and Selectivity
      8. 5.9.8  Linear IF Chain and AGC Settings
      9. 5.9.9  AGC Settling
      10. 5.9.10 Preamble Length and Sync Word
      11. 5.9.11 Carrier Sense
      12. 5.9.12 Automatic Power-up Sequencing
      13. 5.9.13 Automatic Frequency Control
      14. 5.9.14 Digital FM
    10. 5.10 Transmitter
      1. 5.10.1 FSK Modulation Formats
      2. 5.10.2 Output Power Programming
      3. 5.10.3 TX Data Latency
      4. 5.10.4 Reducing Spurious Emission and Modulation Bandwidth
    11. 5.11 Input and Output Matching and Filtering
    12. 5.12 Frequency Synthesizer
      1. 5.12.1 VCO, Charge Pump and PLL Loop Filter
      2. 5.12.2 VCO and PLL Self-Calibration
      3. 5.12.3 PLL Turn-on Time Versus Loop Filter Bandwidth
      4. 5.12.4 PLL Lock Time Versus Loop Filter Bandwidth
    13. 5.13 VCO and LNA Current Control
    14. 5.14 Power Management
    15. 5.15 On-Off Keying (OOK)
    16. 5.16 Crystal Oscillator
    17. 5.17 Built-in Test Pattern Generator
    18. 5.18 Interrupt on Pin DCLK
      1. 5.18.1 Interrupt Upon PLL Lock
      2. 5.18.2 Interrupt Upon Received Signal Carrier Sense
    19. 5.19 PA_EN and LNA_EN Digital Output Pins
      1. 5.19.1 Interfacing an External LNA or PA
      2. 5.19.2 General Purpose Output Control Pins
      3. 5.19.3 PA_EN and LNA_EN Pin Drive
    20. 5.20 System Considerations and Guidelines
      1. 5.20.1 SRD Regulations
      2. 5.20.2 Narrowband Systems
      3. 5.20.3 Low Cost Systems
      4. 5.20.4 Battery Operated Systems
      5. 5.20.5 High Reliability Systems
      6. 5.20.6 Frequency Hopping Spread Spectrum Systems (FHSS)
    21. 5.21 Antenna Considerations
    22. 5.22 Configuration Registers
      1. 5.22.1 Memory
  6. 6Applications, Implementation, and Layout
    1. 6.1 Application Information
      1. 6.1.1 Typical Application
    2. 6.2 Design Requirements
      1. 6.2.1 Input and Output Matching
      2. 6.2.2 Bias Resistor
      3. 6.2.3 PLL Loop Filter
      4. 6.2.4 Crystal
      5. 6.2.5 Additional Filtering
      6. 6.2.6 Power Supply Decoupling and Filtering
    3. 6.3 PCB Layout Recommendations
  7. 7Device and Documentation Support
    1. 7.1 Device Support
      1. 7.1.1 Device Nomenclature
    2. 7.2 Documentation Support
      1. 7.2.1 Community Resources
    3. 7.3 Trademarks
    4. 7.4 Electrostatic Discharge Caution
    5. 7.5 Export Control Notice
    6. 7.6 Glossary
  8. 8Mechanical Packaging and Orderable Information
    1. 8.1 Packaging Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

5.16 Crystal Oscillator

The recommended crystal frequency is 14.7456 MHz, but any crystal frequency in the range 4 to 20 MHz can be used. Using a crystal frequency different from 14.7456 MHz might in some applications give degraded performance. Refer to AN022 Crystal Frequency Selection (SWRA070) for more details on the use of other crystal frequencies than 14.7456 MHz. The crystal frequency is used as reference for the data rate (as well as other internal functions) and in the 4 to 20 MHz range the frequencies 4.9152, 7.3728, 9.8304, 12.2880, 14.7456, 17.2032, 19.6608 MHz will give accurate data rates (as shown in Table 5-4) and an IF frequency of 307.2 kHz. The crystal frequency will influence the programming of the CLOCK_A, CLOCK_B and MODEM registers.

An external clock signal or the internal crystal oscillator can be used as main frequency reference. An external clock signal should be connected to XOSC_Q1, while XOSC_Q2 should be left open. The XOSC_BYPASS bit in the INTERFACE register should be set to ‘1’ when an external digital rail-to-rail clock signal is used. No DC block should be used then. A sine with smaller amplitude can also be used. A DC blocking capacitor must then be used (10 nF) and the XOSC_BYPASS bit in the INTERFACE register should be set to ‘0’. For input signal amplitude, see Section 4.8.

Using the internal crystal oscillator, the crystal must be connected between the XOSC_Q1 and XOSC_Q2 pins. The oscillator is designed for parallel mode operation of the crystal. In addition, loading capacitors (C4 and C5) for the crystal are required. The loading capacitor values depend on the total load capacitance, CL, specified for the crystal. The total load capacitance seen between the crystal terminals should equal CL for the crystal to oscillate at the specified frequency.

Equation 33. CC1020 eq019_cl_SWRS046.gif

The parasitic capacitance is constituted by pin input capacitance and PCB stray capacitance. Total parasitic capacitance is typically 8 pF. A trimming capacitor may be placed across C5 for initial tuning if necessary.

The crystal oscillator circuit is shown in Figure 5-30. Typical component values for different values of CL are given in Table 5-15.

The crystal oscillator is amplitude regulated. This means that a high current is required to initiate the oscillations. When the amplitude builds up, the current is reduced to what is necessary to maintain approximately 600 mVpp amplitude. This ensures a fast start-up, keeps the drive level to a minimum and makes the oscillator insensitive to ESR variations. As long as the recommended load capacitance values are used, the ESR is not critical.

The initial tolerance, temperature drift, aging and load pulling should be carefully specified in order to meet the required frequency accuracy in a certain application. By specifying the total expected frequency accuracy in SmartRF Studio together with data rate and frequency separation, the software will estimate the total bandwidth and compare to the available receiver channel filter bandwidth. The software will report any contradictions and a more accurate crystal will be recommended if required.

CC1020 crystal_oscillator_circuit_swrs046.gifFigure 5-30 Crystal Oscillator Circuit

Table 5-15 Crystal Oscillator Component Values

ITEM CL = 12 pF CL = 16 pF CL = 22 pF
C4 6.8 pF 15 pF 27 pF
C5 6.8 pF 15 pF 27 pF