SCPS133K December   2005  – December 2024 PCA9557

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 Functional Block Diagram
    2. 7.2 Feature Description
      1. 7.2.1 RESET
        1. 7.2.1.1 RESET Errata
          1. 7.2.1.1.1 System Impact
          2. 7.2.1.1.2 System Workaround
      2. 7.2.2 Power-On Reset
    3. 7.3 Programming
      1. 7.3.1 I2C Interface
    4. 7.4 Register Maps
      1. 7.4.1 Device Address
      2. 7.4.2 Control Register And Command Byte
      3. 7.4.3 Register Descriptions
        1. 7.4.3.1 Bus Transactions
          1. 7.4.3.1.1 Writes
          2. 7.4.3.1.2 Reads
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Detailed Design Procedure
        1. 8.2.1.1 Minimizing ICC when I/O is Used to Control LED
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Power-On Reset Errata
        1. 8.3.1.1 System Impact
  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

8.2.1.1 Minimizing ICC when I/O is Used to Control LED

When an I/O is used to control an LED, normally it is connected to VCC through a resistor as shown in Figure 8-1. The LED acts as a diode so, when the LED is off, the I/O VIN is about 1.2 V less than VCC. The ΔICC parameter in the Section 5.5 table shows how ICC increases as VIN becomes lower than VCC. Designs needing to minimize current consumption, such as battery power applications, should consider maintaining the I/O pins greater than or equal to VCC when the LED is off.

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 1.2 V. Both of these methods maintain the I/O VIN at or above VCC and prevent additional supply-current consumption when the LED is off.

PCA9557 High-Value Resistor in Parallel with the LEDFigure 8-2 High-Value Resistor in Parallel with the LED
PCA9557 Device Supplied by a Low VoltageFigure 8-3 Device Supplied by a Low Voltage