SLVSF29C October   2019  – August 2021 TPS8804

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 System Power-up
      2. 7.3.2 LDO Regulators
        1. 7.3.2.1 Power LDO Regulator
        2. 7.3.2.2 Internal LDO Regulator
        3. 7.3.2.3 Microcontroller LDO Regulator
      3. 7.3.3 Photo Chamber AFE
        1. 7.3.3.1 Photo Input Amplifier
        2. 7.3.3.2 Photo Gain Amplifier
      4. 7.3.4 LED Driver
        1. 7.3.4.1 LED Current Sink
        2. 7.3.4.2 LED Voltage Supply
      5. 7.3.5 Carbon Monoxide Sensor AFE
        1. 7.3.5.1 CO Transimpedance Amplifier
        2. 7.3.5.2 CO Connectivity Test
      6. 7.3.6 SLC Interface Transmitter and Receiver
        1. 7.3.6.1 SLC Transmitter
        2. 7.3.6.2 SLC Receiver
      7. 7.3.7 AMUX
      8. 7.3.8 Analog Bias Block and 8 MHz Oscillator
      9. 7.3.9 Interrupt Signal Alerts
    4. 7.4 Device Functional Modes
      1. 7.4.1 Fault States
        1. 7.4.1.1 MCU LDO Fault
        2. 7.4.1.2 Over-Temperature Fault
    5. 7.5 Programming
    6. 7.6 Register Maps
      1. 7.6.1  REVID Register (Offset = 0h) [reset = 0h]
      2. 7.6.2  STATUS1 Register (Offset = 1h) [reset = 0h]
      3. 7.6.3  STATUS2 Register (Offset = 2h) [reset = 0h]
      4. 7.6.4  MASK Register (Offset = 3h) [reset = 0h]
      5. 7.6.5  CONFIG1 Register (Offset = 4h) [reset = 20h]
      6. 7.6.6  CONFIG2 Register (Offset = 5h) [reset = 0h]
      7. 7.6.7  ENABLE1 Register (Offset = 6h) [reset = 0h]
      8. 7.6.8  ENABLE2 Register (Offset = 7h) [reset = 0h]
      9. 7.6.9  CONTROL Register (Offset = 8h) [reset = 0h]
      10. 7.6.10 GPIO_AMUX Register (Offset = Bh) [reset = 0h]
      11. 7.6.11 COSW Register (Offset = Ch) [reset = 0h]
      12. 7.6.12 CO Register (Offset = Dh) [reset = 0h]
      13. 7.6.13 LEDLDO Register (Offset = Fh) [reset = 0h]
      14. 7.6.14 PH_CTRL Register (Offset = 10h) [reset = 0h]
      15. 7.6.15 LED_DAC_A Register (Offset = 11h) [reset = 0h]
      16. 7.6.16 LED_DAC_B Register (Offset = 12h) [reset = 0h]
  8. 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 Photo Amplifier Component Selection
        2. 8.2.2.2 LED Driver Component Selection
        3. 8.2.2.3 LED Voltage Supply Selection
        4. 8.2.2.4 Regulator Component Selection
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1 Photo Amplifier Layout
      2. 10.1.2 CO Amplifier Layout
      3. 10.1.3 Ground Plane Layout
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.7 AMUX

GUID-1F595F16-B172-42A9-A57E-9EBE15B02AE1-low.gif Figure 7-7 Analog Multiplexer Circuit

The AMUX switch and buffer are used to connect the various TPS8804 amplifier outputs to a single ADC. The unity-gain amplifier improves the drive strength and fidelity of the analog signals when connected to an ADC. A 330 pF to 1 nF capacitor must be connected to the AMUX pin to stabilize its output. The 10-kΩ resistor filters high-frequency noise in the analog signal. Using a 10-kΩ resistor and 1-nF capacitor reduces noise levels in the photo amplifier signal. The buffer has the option of being bypassed to remove the added offset introduced by the unity-gain amplifier. Because the AMUX requires the bias block (see Section 7.3.8), bypassing the buffer does not eliminate the AMUX current consumption.