SLVAET3 October   2021 TPS8802

 

  1.   Trademarks
  2. 1Introduction
  3. 2System Architecture
    1. 2.1 Battery Voltage
    2. 2.2 VCC Supply
      1. 2.2.1 Connecting VCC to VBST
      2. 2.2.2 Connecting VCC to VBAT Through a Switch
    3. 2.3 MCU Supply
      1. 2.3.1 MCU Connected to VBAT
      2. 2.3.2 MCU Connected to MCU LDO
      3. 2.3.3 MCU with VCC Connected to VBAT Through a Switch
    4. 2.4 Photoelectric Smoke Sensor LED Supply
      1. 2.4.1 LED Connected to VBAT
      2. 2.4.2 LED Connected to PLDO
      3. 2.4.3 LED Connected to LEDLDO
    5. 2.5 Example Schematics
      1. 2.5.1 Smoke and CO Schematics
      2. 2.5.2 Smoke-Only Schematics
  4. 3Current Consumption
    1. 3.1 Standby Current
      1. 3.1.1 TPS8802 Standby Current
      2. 3.1.2 Microcontroller Standby Current
    2. 3.2 Measurement Current
      1. 3.2.1 Smoke Measurement Current
      2. 3.2.2 CO Measurement Current
      3. 3.2.3 Battery Test Current
      4. 3.2.4 User Alarm Test Current
    3. 3.3 Other Current Consumption
      1. 3.3.1 Boost Charge Current
      2. 3.3.2 Initialization Current
  5. 4System Power Calculation and Measurements
    1. 4.1 Power Calculation Spreadsheet
      1. 4.1.1 Power Consumption Overview Page
      2. 4.1.2 Detailed Calculation Pages
    2. 4.2 Power Consumption Measurements
      1. 4.2.1 Power Measurement Method
      2. 4.2.2 Smoke and CO System Measurements
      3. 4.2.3 Smoke-Only System Measurements
  6. 5Summary
  7. 6References

1 Introduction

New smoke alarm regulations often require a 10-year battery life if the battery is the only power source. Battery selection in these alarms is highly dependent on the system power consumption, and lower power alarms have smaller, lower cost batteries. Achieving low power consumption requires low standby currents and careful management of the smoke alarm regulators, drivers, and amplifiers. The TPS8802 smoke alarm analog front end (AFE) integrates configurable regulators, drivers, and amplifiers with low active and standby currents for achieving 10-year battery life with a single lithium primary battery. The TPS8802 supports multi-wavelength photoelectric smoke sensors, carbon monoxide (CO) sensors, and a variety of battery configurations, all of which are explored in the context of power consumption.