SCPS299A May   2025  – September 2025 TXE8116-Q1 , TXE8124-Q1

ADVANCE INFORMATION  

  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 SPI Bus Timing Requirements
    8. 5.8 Switching 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 Interrupt Output (INT)
      3. 7.3.3 Reset Input (RESET)
      4. 7.3.4 Fail-safe Mode
      5. 7.3.5 Software Reset Call
      6. 7.3.6 Burst Mode
      7. 7.3.7 Daisy Chain
      8. 7.3.8 Multi Port
    4. 7.4 Device Functional Modes
      1. 7.4.1 Power-On Reset
    5. 7.5 Programming
      1. 7.5.1 SPI Interface
      2. 7.5.2 SPI Data Format
      3. 7.5.3 Writes
      4. 7.5.4 Reads
    6. 7.6 Register Maps
      1. 7.6.1 Control Register: Read/Write and Feature Address (B23 - B16)
      2. 7.6.2 Control Register: Port Selection and Multi Port (B15 - B8)
      3. 7.6.3 Register Descriptions
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Power Supply Recommendations
      1. 8.2.1 Power-On Reset Requirements
    3. 8.3 Layout
      1. 8.3.1 Layout Guidelines
      2. 8.3.2 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

7.1 Overview

The TXE81XX-Q1 digital core consists of 24-bit registers, which allow the user to configure the I/O port characteristics. At power on or after a reset, the I/Os are configured as inputs. However, the system controller can configure the I/Os as either inputs or outputs by writing to the direction configuration registers. The data for each input or output is kept in the corresponding Input Port or Output Port register. The polarity of the Input Port register can be inverted with the Polarity Inversion register. All registers, except software reset register, are readable by the system controller.

The TXE81XX-Q1 has configurable I/O functionality which is specifically targeted to enhance the I/O ports. The configurable I/O features and registers include enabling or disabling pull-up and pull-down resistors, latchable inputs, maskable interrupts, interrupt status register, and individual programmable open-drain or push-pull outputs. These configuration registers improve the I/O by increasing flexibility and allowing the user to optimize their design for power consumption and speed.

Other features of the device include an interrupt that is generated on the INT pin whenever an input port changes state. The device can be reset to its default state by applying a low logic level to the RESET pin, issuing a software reset command, or by cycling power to the device and causing a power-on reset. The TXE81XX-Q1 open-drain interrupt (INT) output is activated when any input state differs from its corresponding Input Port register state and is used to indicate to the system controller that an input state has changed. The INT pin can be connected to the interrupt input of a processor. By sending an interrupt signal on this line, the device can inform the processor if there is incoming data on the remote I/O ports without having to communicate via the SPI bus. The device remains a simple target device.

In the event of a timeout or other improper operation, the system controller resets the device by asserting a low on the RESET input pin or by cycling the power to the VCC pin and causing a power-on reset (POR). A reset puts the registers in their default state and initializes the SPI state machine. The RESET feature and a POR cause the same reset/initialization to occur, but the RESET feature does so without needing to power down the device.