SCPS292 July   2025 TCA9539A-Q1

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 I2C Interface Timing Requirements
    7. 5.7 RESET Timing Requirements
    8. 5.8 Switching Characteristics
    9. 5.9 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 I/O Port
      2. 7.3.2 RESET Input
      3. 7.3.3 Interrupt ( INT) Output
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-On Reset
    5. 7.5 Programming
      1. 7.5.1 I2C Interface
    6. 7.6 Register Map
      1. 7.6.1 Device Address
      2. 7.6.2 Control Register And Command Byte
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Calculating Junction Temperature and Power Dissipation
        2. 8.2.2.2 Minimizing ICC When I/Os Control LEDs
      3. 8.2.3 Application Curves
    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

8.2.2.2 Minimizing ICC When I/Os Control LEDs

When an I/O is used to control an LED, normally it is connected to VCC through a resistor (see Figure 8-1). Because the LED acts as a diode, when the LED is off, the I/O VIN is about 1.2V less than VCC. The ΔICC parameter in the Electrical Characteristics table show how ICC increases as VIN becomes lower than VCC. For battery-powered applications, it is essential that the voltage of I/O pins is greater than or equal to VCC, when the LED is off, to minimize current consumption.

Figure 8-2 shows a high-value resistor in parallel with the LED. Figure 8-3 shows VCC less than the LED supply voltage by at least 1.2V. Both of these methods maintain the I/O VCC at or above VCC and prevent additional supply-current consumption when the LED is off.

Take care to make sure that the recommended maximum IOL through the ports not be violated based upon junction temperature. See the Recommended Operating Conditions for more information.

TCA9539A-Q1 High-Value Resistor In Parallel With LEDFigure 8-2 High-Value Resistor In Parallel With LED
TCA9539A-Q1 Device Supplied By Lower VoltageFigure 8-3 Device Supplied By Lower Voltage