SCBS881E January   2010  – October 2018 TMS3705

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 Signal Descriptions
  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 for D (SOIC) Package
    6. 5.6 Switching Characteristics
    7. 5.7 Timing Diagrams
  6. 6Detailed Description
    1. 6.1  Power Supply
    2. 6.2  Oscillator
    3. 6.3  Predrivers
    4. 6.4  Full Bridge
    5. 6.5  RF Amplifier
    6. 6.6  Band-Pass Filter and Limiter
    7. 6.7  Diagnosis
    8. 6.8  Power-on Reset
    9. 6.9  Frequency Divider
    10. 6.10 Digital Demodulator
    11. 6.11 Transponder Resonance-Frequency Measurement
    12. 6.12 SCI Encoder
    13. 6.13 Control Logic
    14. 6.14 Test Pins
  7. 7Applications, Implementation, and Layout
    1. 7.1 Application Diagram
  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 Community Resources
    6. 8.6 Trademarks
    7. 8.7 Electrostatic Discharge Caution
    8. 8.8 Export Control Notice
    9. 8.9 Glossary
  9. 9Mechanical, Packaging, and Orderable Information

Package Options

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

Transponder Resonance-Frequency Measurement

During the prebit reception phase, the bits the transponder transmits show the low-bit frequency, which is the resonance frequency of the transponder. The time periods of the prebits are evaluated by the demodulator counter. Based on the counter states, an algorithm is implemented that ensures a correct measurement of the resonance frequency of the transponder:

  1. A time period of the low-bit frequency has a counter state between 112 and 125.
  2. The measurement of the low-bit frequency (the average of eight subsequent counter states) is accepted during the write mode, when the eight time periods have counter states in the defined range. The measurement during write mode is started with the falling edge at TXCT using the fixed delay time at which end the full bridge is switched on again.
  3. The counter state of the measured low-bit frequency results in the average counter state of an accepted measurement and can be used to update the register of the programmable frequency divider.
  4. The measurement of the low-bit frequency (the average of eight subsequent counter states) is accepted during the read mode, when the eight time periods have counter states in the defined range. The start of the measurement during read mode is delayed to use a stable input signal for the measurement.
  5. The threshold to distinguish between high-bit and low-bit frequency is calculated to be by a value of 5 or 7 (see hysteresis in threshold) higher than the counter state of the measured low-bit frequency.