SLVSJQ4 May   2026 TMF0020

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Timing Requirements
    7. 5.7 Functional Tests
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 20480-Bit FRAM
      2. 6.3.2 FRAM Status Memory
      3. 6.3.3 Address Registers and Transfer Status
      4. 6.3.4 Writing Data to the FRAM
      5. 6.3.5 TMF0020 Device ID
      6. 6.3.6 Bus Termination
    4. 6.4 Device Functional Modes
      1. 6.4.1 Test Procedures for Functional Tests
        1. 6.4.1.1 Multiple Target Configurations
    5. 6.5 Programming
      1. 6.5.1 Serial Communication
      2. 6.5.2 Initialization
      3. 6.5.3 ROM Commands
        1. 6.5.3.1 READ ROM Command [33h]
        2. 6.5.3.2 MATCH ROM Command [55h]
        3. 6.5.3.3 SKIP ROM Command [CCh]
        4. 6.5.3.4 SEARCH ROM Command [F0h]
        5. 6.5.3.5 RESUME Command [A5h]
        6. 6.5.3.6 OVERDRIVE SKIP ROM Command [3Ch]
        7. 6.5.3.7 OVERDRIVE MATCH ROM Command [69h]
      4. 6.5.4 Memory Function Commands
        1. 6.5.4.1 Write Scratchpad Command [0Fh]
        2. 6.5.4.2 Read Scratchpad Command [AAh]
        3. 6.5.4.3 Copy Scratchpad [55h]
        4. 6.5.4.4 Read Memory [F0h]
        5. 6.5.4.5 Extended Read Memory [A5h]
        6. 6.5.4.6 Memory Command Flow Charts
      5. 6.5.5 SDQ single-wire serial interface Signaling
        1. 6.5.5.1 RESET and PRESENCE PULSE
        2. 6.5.5.2 Write-Read-Time Slots
      6. 6.5.6 IDLE
      7. 6.5.7 CRC Generation
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information
    1. 10.1 Packaging Information
    2. 10.2 Tape and Reel Information

7.3 Power Supply Recommendations

The TMF0020 is a low-power device that only needs to turn on when communicating. The device power comes from the voltage supply used for digital I/O in the system. A dedicated VCC pin does not exist in the device; a supply input bypass capacitor is not required or recommended. The device obtains power from the SDQ single-wire serial interface communication input which is sustainable during normal communication activity.

The ramp time of the SDQ single-wire serial interface voltage when power is initially applied can be slow due to current limiting from the source. Ramp times greater than 200µs can cause undesired bouncing of the POR circuit and result in the device not generating a presence pulse. To account for this undesired effect on the device, a best practice for the communication host is to issue a hard reset to the device by pulling down the SDQ single-wire serial interface line for >5ms and then releasing the SDQ single-wire serial interface bus before issuing the reset pulse that is approximately 480µs long.

Figure 7-4 illustrates the best practice for dealing with initial power on ramps.

TMF0020 Power-Up Best PracticeFigure 7-4 Power-Up Best Practice
  1. Initial power-on ramps can be long in duration.
  2. The host issues a hard reset of > 5ms, resetting the device
  3. TMF0020 responds to the hard reset by issuing a presence pulse.
  4. Apply a soft reset of approximately 480µs after the previous presence pulse.
  5. TMF0020 responds to the soft reset by issuing a presence pulse.