SCPS146G October   2005  – March 2021 PCA9544A

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  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 Interrupt Timing Requirements
  7. 7 Parameter Measurement Information
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
    4. 8.4 Device Functional Modes
      1. 8.4.1 Power-On Reset
    5. 8.5 Programming
      1. 8.5.1 I2C Interface
    6. 8.6 Register Map
      1. 8.6.1 Control Register
        1. 8.6.1.1 Device Address
        2. 8.6.1.2 Control Register Description
        3. 8.6.1.3 Control Register Definition
        4. 8.6.1.4 Interrupt Handling
  9. 9 Application Information Disclaimer
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
  10. 10Power Supply Recommendations
    1. 10.1 Power-On Reset Requirements
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Receiving Notification of Documentation Updates
    2. 12.2 Support Resources
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.6.1.4 Interrupt Handling

The PCA9544A provides four interrupt inputs (one for each channel) and one open-drain interrupt output. When an interrupt is generated by any device, it is detected by the PCA9544A, and the interrupt output is driven low. The channel does not need to be active for detection of the interrupt. A bit also is set in the control register (see Table 8-2).

Bits 4–7 of the control register correspond to channels 0–3 of the PCA9544A, respectively. Therefore, if an interrupt is generated by any device connected to channel 1, the state of the interrupt inputs is loaded into the control register when a read is accomplished. Likewise, an interrupt on any device connected to channel 0 causes bit 4 of the control register to be set on the read. The master then can address the PCA9544A and read the contents of the control register to determine which channel contains the device generating the interrupt. The master can reconfigure the PCA9544A to select this channel and locate the device generating the interrupt and clear it. Once the device responsible for the interrupt clears, the interrupt clears.

It should be noted that more than one device can provide an interrupt on a channel, so it is up to the master to ensure that all devices on a channel are interrogated for an interrupt.

The interrupt inputs can be used as general-purpose inputs if the interrupt function is not required.

If unused, interrupt input(s) must be connected to VCC.

Table 8-2 Control Register Read (Interrupt)(1)
INT3INT2INT1INT0D3B2B1B0COMMAND
XXX0XXXXNo interrupt on channel 0
1Interrupt on channel 0
XX0XXXXXNo interrupt on channel 1
1Interrupt on channel 1
X0XXXXXXNo interrupt on channel 2
1Interrupt on channel 2
0XXXXXXXNo interrupt on channel 3
1Interrupt on channel 3
(1) Several interrupts can be active at the same time. For example, INT3 = 0, INT2 = 1, INT1 = 1, INT0 = 0 means that there is no interrupt on channels 0 and 3, and there is interrupt on channels 1 and 2.