ZHCSNM0F September   2006  – March 2021 PCA9554A

PRODUCTION DATA  

  1. 1 特性
  2. 2 说明
  3. 3 Revision History
  4. 4 Description (Continued)
  5. 5 Pin Configuration And Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 I2C Interface Timing Requirements
    7. 6.7 Switching Characteristics
    8. 6.8 Typical Characteristics
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Functional Block Diagram
    2. 8.2 Device Functional Modes
      1. 8.2.1 Power-On Reset
      2. 8.2.2 I/O Port
      3. 8.2.3 Interrupt Output ( INT)
        1. 8.2.3.1 Interrupt Errata
          1. 8.2.3.1.1 Description
          2. 8.2.3.1.2 System Impact
          3. 8.2.3.1.3 System Workaround
    3. 8.3 Programming
      1. 8.3.1 I2C Interface
      2. 8.3.2 Register Map
        1. 8.3.2.1 Device Address
        2. 8.3.2.2 Control Register And Command Byte
        3. 8.3.2.3 Register Descriptions
        4. 8.3.2.4 Bus Transactions
          1. 8.3.2.4.1 Writes
          2. 8.3.2.4.2 Reads
  9. 9 Application Information Disclaimer
    1. 9.1 Application Information
      1. 9.1.1 Typical Application
        1. 9.1.1.1 Detailed Design Procedure
          1. 9.1.1.1.1 Minimizing ICC When I/Os Control Leds
  10. 10Power Supply Recommendations
    1. 10.1 Power-On Reset Requirements
  11. 11Device and Documentation Support
    1. 11.1 支持资源
    2. 11.2 Trademarks
    3. 11.3 静电放电警告
    4. 11.4 术语表
  12. 12Mechanical, Packaging, and Orderable Information

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9.1.1.1.1 Minimizing ICC When I/Os Control Leds

When the I/Os are used to control LEDs, they are normally connected to VCC through a resistor as shown in Figure 9-1. Because the LED acts as a diode, when the LED is off, the I/O VIN is about 1.2 V less than VCC. The supply current, ICC, increases as VIN becomes lower than VCC and is specified as ΔICC in Electrical Characteristics.

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 9-2 shows a high-value resistor in parallel with the LED. Figure 9-3 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 prevents additional supply-current consumption when the LED is off.

GUID-6095346C-C89F-4A37-B85C-1E4439FC071D-low.gifFigure 9-2 High-Value Resistor In Parallel With The Led
GUID-82BB557B-1A86-4BF2-A67A-DB2C45A01D05-low.gifFigure 9-3 Device Supplied By A Lower Voltage