SLVSF25C September   2019  – August 2021 TPS8802

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 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  System Power-up
      2. 8.3.2  LDO Regulators
        1. 8.3.2.1 Power LDO Regulator
        2. 8.3.2.2 Internal LDO Regulator
        3. 8.3.2.3 Microcontroller LDO Regulator
      3. 8.3.3  Photo Chamber AFE
        1. 8.3.3.1 Photo Input Amplifier
        2. 8.3.3.2 Photo Gain Amplifier
      4. 8.3.4  LED Driver
        1. 8.3.4.1 LED Current Sink
        2. 8.3.4.2 LED Voltage Supply
      5. 8.3.5  Carbon Monoxide Sensor AFE
        1. 8.3.5.1 CO Transimpedance Amplifier
        2. 8.3.5.2 CO Connectivity Test
      6. 8.3.6  Boost Converter
        1. 8.3.6.1 Boost Hysteretic Control
        2. 8.3.6.2 Boost Soft Start
      7. 8.3.7  Interconnect Driver
      8. 8.3.8  Piezoelectric Horn Driver
        1. 8.3.8.1 Three-Terminal Piezo
        2. 8.3.8.2 Two-Terminal Piezo
      9. 8.3.9  Battery Test
      10. 8.3.10 AMUX
      11. 8.3.11 Analog Bias Block and 8 MHz Oscillator
      12. 8.3.12 Interrupt Signal Alerts
    4. 8.4 Device Functional Modes
      1. 8.4.1 Sleep Mode
      2. 8.4.2 Fault States
        1. 8.4.2.1 MCU LDO Fault
        2. 8.4.2.2 Over-Temperature Fault
    5. 8.5 Programming
    6. 8.6 Register Maps
      1. 8.6.1  REVID Register (Offset = 0h) [reset = 0h]
      2. 8.6.2  STATUS1 Register (Offset = 1h) [reset = 0h]
      3. 8.6.3  STATUS2 Register (Offset = 2h) [reset = 0h]
      4. 8.6.4  MASK Register (Offset = 3h) [reset = 0h]
      5. 8.6.5  CONFIG1 Register (Offset = 4h) [reset = 20h]
      6. 8.6.6  CONFIG2 Register (Offset = 5h) [reset = 2h]
      7. 8.6.7  ENABLE1 Register (Offset = 6h) [reset = 10h]
      8. 8.6.8  ENABLE2 Register (Offset = 7h) [reset = 0h]
      9. 8.6.9  CONTROL Register (Offset = 8h) [reset = 0h]
      10. 8.6.10 SLPTMR1 Register (Offset = 9h) [reset = 0h]
      11. 8.6.11 SLPTMR2 Register (Offset = Ah) [reset = 0h]
      12. 8.6.12 GPIO_AMUX Register (Offset = Bh) [reset = 0h]
      13. 8.6.13 CO_BATTEST Register (Offset = Ch) [reset = 0h]
      14. 8.6.14 CO Register (Offset = Dh) [reset = 0h]
      15. 8.6.15 VBOOST Register (Offset = Eh) [reset = F2h]
      16. 8.6.16 LEDLDO Register (Offset = Fh) [reset = 0h]
      17. 8.6.17 PH_CTRL Register (Offset = 10h) [reset = 0h]
      18. 8.6.18 LED_DAC_A Register (Offset = 11h) [reset = 0h]
      19. 8.6.19 LED_DAC_B Register (Offset = 12h) [reset = 0h]
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
        1. 9.2.2.1 Photo Amplifier Component Selection
        2. 9.2.2.2 LED Driver Component Selection
        3. 9.2.2.3 LED Voltage Supply Selection
        4. 9.2.2.4 Boost Converter Component Selection
        5. 9.2.2.5 Regulator Component Selection
      3. 9.2.3 Application Curves
      4. 9.2.4 3V Battery Smoke and CO Alarm
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 Photo Amplifier Layout
      2. 11.1.2 CO Amplifier Layout
      3. 11.1.3 Boost Converter Layout
      4. 11.1.4 Ground Plane Layout
    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

8.3.3.2 Photo Gain Amplifier

The high-bandwidth, low noise photo gain amplifier connects to the output of the photo input stage to further amplify the photodiode signal. The gain amplifier is adjustable on-the-fly using the I2C interface. The gain amplifier has four settings:

  • 5x (4.75x if PREF_SEL=1)
  • 11x (10.4x if PREF_SEL=1)
  • 20x (18.5x if PREF_SEL=1)
  • 35x (32.3x if PREF_SEL=1)

The gain stage has the option of being referenced to GND or PREF with the PREF_SEL bit. When PREF_SEL=1, a 5 mV reference offset counteracts the gain stage's input offset voltage to keep the gain stage output above 50 mV. The 5 mV reference offset is amplified by the gain stage, causing the output to change when the gain is changed, even when there is zero photo-current. It is recommended to connect a 470 kΩ resistor from PREF to VINT if the gain is set to 11x, 20x, or 35x. This resistor changes the PREF voltage to 70 mV and prevents the output from dropping below 50 mV in worst-case conditions. Referencing the gain stage to PREF causes the 50 mV reference to change with signal level due to the finite impedance of the reference. Because the reference is changing with the signal level, the gain is slightly less with PREF_SEL=1.