SDLS972B April   2023  – April 2024 LSF0102

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  LSF0102 AC Performance (Translating Down) Switching Characteristics , VCCB = 3.3V
    7. 5.7  LSF0102 AC Performance (Translating Down) Switching Characteristics, VCCB = 2.5V
    8. 5.8  LSF0102 AC Performance (Translating Up) Switching Characteristics, VCCB = 3.3V
    9. 5.9  LSF0102 AC Performance (Translating Up) Switching Characteristics, VCCB = 2.5V
    10. 5.10 Typical Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Auto Bidirectional Voltage Translation
      2. 7.3.2 Output Enable
    4. 7.4 Device Functional Modes
      1. 7.4.1 Up and Down Translation
        1. 7.4.1.1 Up Translation
        2. 7.4.1.2 Down Translation
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Open-Drain Interface (I2C, PMBus, SMBus, and GPIO)
        1. 8.2.1.1 Design Requirements
          1. 8.2.1.1.1 Enable, Disable, and Reference Voltage Guidelines
          2. 8.2.1.1.2 Bias Circuitry
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1 Bidirectional Translation
          2. 8.2.1.2.2 Pull-Up Resistor Sizing
        3. 8.2.1.3 Application Curve
      2. 8.2.2 Mixed-Mode Voltage Translation
      3. 8.2.3 Single Supply Translation
      4. 8.2.4 Voltage Translation for Vref_B < Vref_A + 0.8V
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Mechanical, Packaging, and Orderable Information
  12. 11Revision History

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • DCU|8
  • DDF|8
  • YZT|8
  • DCT|8
  • DQE|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.2.3 Single Supply Translation

Sometimes, an external device will have an unknown voltage that could be above or below the desired translation voltage, preventing a normal connection of the LSF. Resistors are added on the A side in place of the second supply in this case – this is an example of when LSF single supply operation is utilized, shown in Figure 9-5. In the following figure, a single 3.3V supply is used to translate between a 3.3V device and a device that can change between 1.8V and 5.0V. R1 and R2 are added in place of the second supply. Note that due to some current coming out of the Vref_A pin, this cannot be treated as a simple voltage divider.

GUID-20230419-SS0I-LRCS-60WS-CZGBMBS6TVQP-low.svg Figure 8-5 Single Supply Translation with 3.3V Supply

The steps to select the resistor values for R1 and R2 are as follows:

  1. Select a value for R1. Typically, 1MΩ is used to reduce current consumption.
  2. Plug in values for your system into the following equation. Note that Vref_A is the lowest voltage in the system. VCCB is the primary supply and R1 is the selected value from step 1.

Equation 4. R2 = 200 (103) × R1 × VREFA(200 (103) + R1)(VCCB - VREFA) - 0.85 × R1 

The single supply used must be at least 0.8V larger than the lowest desired translation voltage. The voltage at Vref_A must be selected as the lowest voltage to be used in the system. The LSF evaluation module (LSF-EVM) contains unpopulated pads to place R1 and R2 for single supply operation testing. For an example single supply translation schematic and details, see the Single Supply Translation with the LSF Family video.