SLOS743M August   2011  – March 2020

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. 3Device Characteristics
    1. 3.1 Related Products
  4. 4Terminal Configuration and Functions
    1. 4.1 Pin Diagram
    2. 4.2 Signal Descriptions
      1. Table 4-1 Terminal Functions
  5. 5Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Electrical Characteristics
    5. 5.5 Thermal Resistance Characteristics
    6. 5.6 Switching Characteristics
  6. 6Detailed Description
    1. 6.1  Overview
      1. 6.1.1 RFID and NFC Operation – Reader and Writer
      2. 6.1.2 NFC Device Operation – Initiator
      3. 6.1.3 NFC Device Operation – Target
        1. 6.1.3.1 Active Target
        2. 6.1.3.2 Passive Target
        3. 6.1.3.3 Card Emulation
    2. 6.2  System Block Diagram
    3. 6.3  Power Supplies
      1. 6.3.1 Supply Arrangements
      2. 6.3.2 Supply Regulator Settings
      3. 6.3.3 Power Modes
    4. 6.4  Receiver – Analog Section
      1. 6.4.1 Main and Auxiliary Receivers
      2. 6.4.2 Receiver Gain and Filter Stages
    5. 6.5  Receiver – Digital Section
      1. 6.5.1 Received Signal Strength Indicator (RSSI)
        1. 6.5.1.1 Internal RSSI – Main and Auxiliary Receivers
        2. 6.5.1.2 External RSSI
    6. 6.6  Oscillator Section
    7. 6.7  Transmitter – Analog Section
    8. 6.8  Transmitter – Digital Section
    9. 6.9  Transmitter – External Power Amplifier and Subcarrier Detector
    10. 6.10 TRF7970A IC Communication Interface
      1. 6.10.1 General Introduction
        1. 6.10.1.1 Continuous Address Mode
        2. 6.10.1.2 Noncontinuous Address Mode (Single Address Mode)
        3. 6.10.1.3 Direct Command Mode
        4. 6.10.1.4 FIFO Operation
      2. 6.10.2 Parallel Interface Mode
      3. 6.10.3 Reception of Air Interface Data
      4. 6.10.4 Data Transmission From MCU to TRF7970A
      5. 6.10.5 Serial Interface Communication (SPI)
        1. 6.10.5.1 Serial Interface Mode With Slave Select (SS)
      6. 6.10.6 Direct Mode
    11. 6.11 TRF7970A Initialization
    12. 6.12 Special Direct Mode for Improved MIFARE Compatibility
    13. 6.13 NFC Modes
      1. 6.13.1 Target
      2. 6.13.2 Initiator
    14. 6.14 Direct Commands from MCU to Reader
      1. 6.14.1 Command Codes
        1. 6.14.1.1  Idle (0x00)
        2. 6.14.1.2  Software Initialization (0x03)
        3. 6.14.1.3  Initial RF Collision Avoidance (0x04)
        4. 6.14.1.4  Response RF Collision Avoidance (0x05)
        5. 6.14.1.5  Response RF Collision Avoidance (0x06, n = 0)
        6. 6.14.1.6  Reset FIFO (0x0F)
        7. 6.14.1.7  Transmission With CRC (0x11)
        8. 6.14.1.8  Transmission Without CRC (0x10)
        9. 6.14.1.9  Delayed Transmission With CRC (0x13)
        10. 6.14.1.10 Delayed Transmission Without CRC (0x12)
        11. 6.14.1.11 Transmit Next Time Slot (0x14)
        12. 6.14.1.12 Block Receiver (0x16)
        13. 6.14.1.13 Enable Receiver (0x17)
        14. 6.14.1.14 Test Internal RF (RSSI at RX Input With TX ON) (0x18)
        15. 6.14.1.15 Test External RF (RSSI at RX Input with TX OFF) (0x19)
    15. 6.15 Register Description
      1. 6.15.1 Register Preset
      2. 6.15.2 Register Overview
      3. 6.15.3 Detailed Register Description
        1. 6.15.3.1 Main Configuration Registers
          1. 6.15.3.1.1 Chip Status Control Register (0x00)
          2. 6.15.3.1.2 ISO Control Register (0x01)
        2. 6.15.3.2 Control Registers – Sublevel Configuration Registers
          1. 6.15.3.2.1  ISO/IEC 14443 TX Options Register (0x02)
          2. 6.15.3.2.2  ISO/IEC 14443 High-Bit-Rate and Parity Options Register (0x03)
          3. 6.15.3.2.3  TX Timer High Byte Control Register (0x04)
          4. 6.15.3.2.4  TX Timer Low Byte Control Register (0x05)
          5. 6.15.3.2.5  TX Pulse Length Control Register (0x06)
          6. 6.15.3.2.6  RX No Response Wait Time Register (0x07)
          7. 6.15.3.2.7  RX Wait Time Register (0x08)
          8. 6.15.3.2.8  Modulator and SYS_CLK Control Register (0x09)
          9. 6.15.3.2.9  RX Special Setting Register (0x0A)
          10. 6.15.3.2.10 Regulator and I/O Control Register (0x0B)
        3. 6.15.3.3 Status Registers
          1. 6.15.3.3.1  IRQ Status Register (0x0C)
          2. 6.15.3.3.2  Interrupt Mask Register (0x0D) and Collision Position Register (0x0E)
          3. 6.15.3.3.3  RSSI Levels and Oscillator Status Register (0x0F)
          4. 6.15.3.3.4  Special Functions Register (0x10)
          5. 6.15.3.3.5  Special Functions Register (0x11)
          6. 6.15.3.3.6  Adjustable FIFO IRQ Levels Register (0x14)
          7. 6.15.3.3.7  NFC Low Field Level Register (0x16)
          8. 6.15.3.3.8  NFCID1 Number Register (0x17)
          9. 6.15.3.3.9  NFC Target Detection Level Register (0x18)
          10. 6.15.3.3.10 NFC Target Protocol Register (0x19)
        4. 6.15.3.4 Test Registers
          1. 6.15.3.4.1 Test Register (0x1A)
          2. 6.15.3.4.2 Test Register (0x1B)
        5. 6.15.3.5 FIFO Control Registers
          1. 6.15.3.5.1 FIFO Status Register (0x1C)
          2. 6.15.3.5.2 TX Length Byte1 Register (0x1D), TX Length Byte2 Register (0x1E)
  7. 7Applications, Implementation, and Layout
    1. 7.1 TRF7970A Reader System Using SPI With SS Mode
      1. 7.1.1 General Application Considerations
      2. 7.1.2 Schematic
    2. 7.2 Layout Considerations
    3. 7.3 Impedance Matching TX_Out (Pin 5) to 50 Ω
    4. 7.4 Reader Antenna Design Guidelines
  8. 8Device and Documentation Support
    1. 8.1 Getting Started and Next Steps
    2. 8.2 Device Nomenclature
    3. 8.3 Tools and Software
    4. 8.4 Documentation Support
    5. 8.5 Support Resources
    6. 8.6 Trademarks
    7. 8.7 Electrostatic Discharge Caution
    8. 8.8 Glossary
  9. 9Mechanical, Packaging, and Orderable Information

6.6 Oscillator Section

The 13.56-MHz or 27.12-MHz crystal (or oscillator) is controlled by the Chip Status Control register (0x00) and the EN and EN2 terminals. The oscillator generates the RF frequency for the RF output stage as well as the clock source for the digital section. The buffered clock signal is available at pin 27 (SYS_CLK) for any other external circuits. B4 and B5 inside the Modulation and SYS_CLK register (0x09) can be used to divide the external SYS_CLK signal at pin 27 by 1, 2, or 4.

Typical start-up time from complete power down is in the range of 3.5 ms.

During Power Down Mode 2 (EN = 0, EN2 = 1) the frequency of SYS_CLK is switched to 60 kHz (typical).

The crystal needs to be connected between pin 30 and pin 31. The external shunt capacitors values for C1 and C2 must be calculated based on the specified load capacitance of the crystal being used. The external shunt capacitors are calculated as two identical capacitors in series plus the stray capacitance of the TRF7970A and parasitic PCB capacitance in parallel to the crystal.

The parasitic capacitance (CS, stray and parasitic PCB capacitance) can be estimated at 4 to 5 pF (typical).

As an example, using a crystal with a required load capacitance (CL) of 18 pF, the calculation is shown in Equation 1.

Equation 1. C1 = C2 = 2 × (CL– CS) = 2 × (18 pF – 4.5 pF) = 27 pF

A 27-pF capacitor must be placed on pins 30 and 31 to ensure proper crystal oscillator operation.

TRF7970A crystal_block_dgm_trf7970a_slos743.gifFigure 6-7 Crystal Block Diagram

Any crystal used with TRF7970A should meet the minimum characteristics in Table 6-9.

Table 6-9 Minimum Crystal Recommendations

PARAMETER SPECIFICATION
Frequency 13.56 MHz or 27.12 MHz
Mode of operation Fundamental
Type of resonance Parallel
Frequency tolerance ±20 ppm
Aging < 5 ppm/year
Operation temperature range –40°C to 85°C

As an alternative, an external clock oscillator source can be connected to pin 31 to provide the system clock; pin 30 can be left open.