SCPS280B November   2022  – May 2025 TCAL9538

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 I2C Bus 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 Diagrams
    3. 7.3 Feature Description
      1. 7.3.1 I/O Port
      2. 7.3.2 Adjustable Output Drive Strength
      3. 7.3.3 Interrupt Output (INT)
      4. 7.3.4 Reset Input (RESET)
      5. 7.3.5 Software Reset Call
    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 Maps
      1. 7.6.1 Device Address
      2. 7.6.2 Control Register and Command Byte
      3. 7.6.3 Register Descriptions
      4. 7.6.4 Bus Transactions
        1. 7.6.4.1 Writes
        2. 7.6.4.2 Reads
  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 Minimizing ICC When I/Os Control LEDs
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Power-On Reset Requirements
    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 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.2.2.1 Minimizing ICC When I/Os Control LEDs

As shown in Figure 8-2, normally I/Os are connected to VCC through a resistor when the I/Os are used to control LEDs. For a P-port configured as an input, current consumption increases as VI becomes lower than VCC. The LEDs are diodes with threshold voltage VT, and are off when a P-port is configured as an input, but the voltages at the P-port will be equal to VCC minus VT.

For battery-powered applications, it is essential that the voltage of P-ports controlling the LEDs is greater than or equal to VCC when the P-ports are configured as input 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 VT. Both of these methods maintain the I/O VI at or above VCC and prevent additional supply current consumption when the P-port is configured as an input and the LED is off.

TCAL9538 High-Value Resistor in Parallel with LED Figure 8-2 High-Value Resistor in Parallel with LED
TCAL9538 Device Supplied by a Lower Voltage Figure 8-3 Device Supplied by a Lower Voltage