SLLSFN5B June   2023  – September 2025 ISO1228

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  Power Ratings
    6. 5.6  Insulation Specifications
    7. 5.7  Safety-Related Certifications
    8. 5.8  Safety Limiting Values
    9. 5.9  Electrical Characteristics—DC Specification
    10. 5.10 Switching Characteristics—AC Specification
    11. 5.11 Typical Characteristics
  7. 6 Parameter Measurement Information
    1. 6.1 Test Circuits
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Surge Protection
      2. 7.3.2  Field Side LED Indication
      3. 7.3.3  Serial and Parallel Output option
      4. 7.3.4  Cyclic Redundancy Check (CRC)
      5. 7.3.5  FAULT Indication
      6. 7.3.6  Digital Low Pass Filter
      7. 7.3.7  SPI Register Map
      8. 7.3.8  SPI Timing - Non-Daisy Chain
      9. 7.3.9  SPI Timing - Daisy Chain
      10. 7.3.10 SPI Timing - Burst Mode
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Sinking Type Digital Inputs
      2. 8.2.2 Sourcing Type Digital Inputs
      3. 8.2.3 Sink/Source Type Digital Inputs
      4. 8.2.4 Design Requirements
        1. 8.2.4.1 Detailed Design Procedure
          1. 8.2.4.1.1 Current Limit
          2. 8.2.4.1.2 Voltage Thresholds
          3. 8.2.4.1.3 Wire-Break Detection
    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 Documentation Support
      1. 9.1.1 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. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information
8.2.4.1.2 Voltage Thresholds

The RTHR resistor sets the voltage thresholds (VIL and VIH) as well as limits the surge current. A value of 1kΩ is recommended for RTHR in Type 3 systems for IL of 2.9mA (typical) and 910Ω for IL of 3.9mA (typical) in sink mode (maximum threshold voltage required is 11V). IL of 3.9mA is not supported in source mode for Type 2 and Type 3 systems. A value of 1kΩ is recommended for RTHR in Type 1 systems (maximum threshold voltage required is 15V) and a value of 910Ω is recommended for RTHR in Type 2 systems. The Table 8-1 and Source Mode RTHR Admissible Values (Ω) tables list range of RTHR values applicable for each mode. Use Equation 14 and Equation 4 to calculate the values for the typical VIH values and minimum VIL values, respectively.

Equation 3. V I H t y p i c a l = 6.0 V + R T H R × I L ( t y p i c a l )
Equation 4. V I L t y p i c a l = 5.0 V + R T H R × I L ( t y p i c a l )
Equation 5. V I H m a x = 6.4 V + R T H R × I L ( m a x )
Equation 6. V I L m i n = 4.7 V + R T H R × I L ( m i n )

Refer to Sink Mode RTHR Admissible Values (Ω) and Source Mode RTHR Admissible Values (Ω) for the RTHR values used for IEC 61131-2 Type 1 and 3 voltage thresholds. Type 2 operation is also available in sink mode. For Type 2 operation, connect two Type 3 channels in parallel with an RILIM = 1kΩ and RPAR = 9.76kΩ . The resulting Type 2 configuration has a current limit of 7.8mA (typical). RTHR values can be same as Type 3 operation for each parallel channels in this mode.

A tolerance of 5% is acceptable on RTHR for all types. Surge resistant resistors are recommended for RTHR.

Table 8-1 Sink Mode RTHR Admissible Values (Ω)
SINK MODE
RILIM = 0Ω, RPAR = 13kΩ, RSURGE = 1kΩ, (IL = 2.9mA)RILIM = 1kΩ, RPAR = 9.76kΩ, RSURGE = 1kΩ, (IL = 3.9mA)
MinTypicalMaxMinTypicalMax
Type 118010002400Type 11109101740
Type 318010001300Type 3110910930
Table 8-2 Source Mode RTHR Admissible Values (Ω)
SOURCE MODE
RILIM = 0Ω, RPAR = 13kΩ (IL = 2.9mA)RILIM = 1kΩ, RPAR = 9.76kΩ, (IL = 3.9mA)
MinTypicalMaxMinTypicalMax
Type 118010002400Type 1200020002000
Type 318010001300Type 3Not Supported

The values in the tables are calculated using the equations for VIH and VIL mentioned above.

As an example, the values for IEC 61131-2 Type 1 Sink Mode thresholds can be calculated. Assuming RILIM. = 0kΩ, the following data sheet specifications can be used for the calculation:

Equation 7. VOFF_MAX = 5V and must be greater than VIL(min)
Equation 8. VON_MIN = 15V and must be less than VIH(max)
Equation 9. IL(min) = 2mA
Equation 10. IL(max) = 3.3mA

The minimum acceptable value for RTHR can be calculated. When the input is close to the OFF state: VOFF_MAX = VIL(min). The above data sheet values can be substituted into the equation for VIL(min):

Equation 11. VIL(min) = 5V = 4.7V + RTHR × 2mA

The equation is rearranged to solve for RTHR = 150Ω.

VIH(max) can now be calculated using RTHR = 150Ω:

Equation 12. VIH(max) = 6.4V + 150Ω × IL(max) = 6.895V which is less than VON_MIN

Therefore RTHR = 150Ω is changed to 180Ω in the table to accommodate for a 5% tolerance on RTHR using a standard resistor value.

The maximum acceptable value for RTHR can be calculated. When the input is close to the ON state: VON_MIN = VIH(max). The same data sheet values can be substituted into the VIH(max):

Equation 13. VIH(max) = 15V = 6.4V + RTHR × 3.3mA ≥ RTHR = 2.6kΩ

Using RTHR = 2.6kΩ, VOFF = VIL = 6.4V + 2.6kΩ × IL(min) = 9.9V which is greater than VOFF_MAX

Similarly 2400Ω in the table is a standard resistor used to accommodate for 5% tolerance on RTHR. Other values in the table are derived using the same method or download the threshold calculator online.