SDLS967H may   2016  – july 2023 LSF0108-Q1

PRODMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information (Q1)
    5. 6.5 Electrical Characteristics - RKS Package
    6. 6.6 Electrical Characteristics - PW Package
    7. 6.7 Switching Characteristics (Translating Down)
    8. 6.8 Switching Characteristics (Translating Up)
    9. 6.9 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Auto Bidirectional Voltage Translation
      2. 8.3.2 Output Enable
      3. 8.3.3 Wettable Flanks
    4. 8.4 Device Functional Modes
      1. 8.4.1 Up and Down Translation
  10. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 I2C PMBus, SMBus, GPIO
        1. 9.2.1.1 Design Requirements
          1. 9.2.1.1.1 Enable, Disable, and Reference Voltage Guidelines
          2. 9.2.1.1.2 Bias Circuitry
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Bidirectional Translation
          2. 9.2.1.2.2 Pull-Up Resistor Sizing
          3. 9.2.1.2.3 LSF0108-Q1 Bandwidth
        3. 9.2.1.3 Application Curves
      2. 9.2.2 Mixed-Mode Voltage Translation
        1. 9.2.2.1 Single Supply Translation
        2. 9.2.2.2 Voltage Translation for Vref_B < Vref_A + 0.8 V
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information
9.2.1.2.2 Pull-Up Resistor Sizing

The pull-up resistor value needs to limit the current through the pass transistor when it is in the ON state to about 15 mA. Doing this causes a voltage drop of 260 mV to 350 mV to have a valid LOW signal on the downstream channel. If the current through the pass transistor is higher than 15 mA, the voltage drop is also higher in the ON state. To set the current through each pass transistor at 15 mA, calculate the pull-up resistor value using the following equation:

Equation 3. Rpu = (Vpu - 0.35 V)0.015 A 

Table 9-4 provides resistor values, reference voltages, and currents at 8 mA, 5 mA, and 3 mA. The resistor value shown in the +10% column (or a larger value) should be used so that the voltage drop across the transistor is 350 mV or less. The external driver must be able to sink the total current from the resistors on both sides of the LSF family device at 0.175 V, although the 15 mA applies only to current flowing through the LSF family device. The device driving the low state at 0.175 V must sink current from one or more of the pull-up resistors and maintain VOL. A decrease in resistance will increase current, and thus result in increased VOL.

Table 9-4 Pull-Up Resistor Values
VPU(1)(2)8 mA5 mA3 mA
NOMINAL (Ω)+10%(3) (Ω)NOMINAL (Ω)+10%(3) (Ω)NOMINAL (Ω)+10%(3) (Ω)
5 V581639930102315501705
3.3 V3694065906499831082
2.5 V269296430473717788
1.8 V181199290319483532
1.5 V144158230253383422
1.2 V106117170187283312
(1) Calculated for VOL = 0.35 V
(2) Assumes output driver VOL = 0.175 V at stated current
(3) +10% to compensate for VDD range and resistor tolerance