SLVAFL5 September   2023 TPS61299

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction of Water Heater
  5. 2Low Voltage Start-up Boost Converter Introduction
    1. 2.1 General Introduction About TPS61299
    2. 2.2 Introduction about Traditional Start-up Process
    3. 2.3 Down Mode and Boost Mode Operation
  6. 3TPS61299 Ultra-low Voltage Start-up Design
    1. 3.1 Ultra Low Voltage Start-up Set up
    2. 3.2 The Way AVIN influence Start-up Process
    3. 3.3 The Way Vout Influence Start-up Process
    4. 3.4 The Way L Influence Start-up process
      1. 3.4.1 Why With the Larger Inductance, The Smaller PVIN Start-up Can Be Achieved?
      2. 3.4.2 Why Does The Inductance Continue to Increase, The Minimum PVIN to Start Up Is Not Lower
      3. 3.4.3 Why 80 mV Can Start Normally While 70 mV Fail to?
  7. 4Ultra-low Voltage Start-up Design
    1. 4.1 Test Waveform
  8. 5Summary
  9. 6References

1 Introduction of Water Heater

In some energy harvesting applications, the voltage of the input source as low as 150 mV, thus a boost is needed to regulate a higher voltage for the system. Water heater is just a good example: When the water heater is switched on, piezo ceramic fires, a small fire occurs to raise the temperature of the thermocouple, this time due to the temperature difference at both terminals. The thermocouple begins to generate a thermal potential (as low as 150 mV) , acting as the input to the boost converter, which regulates the output to 3.3 V to turn on the control portion of the water heater, as is shown in Figure 1-1. However, it is hard for a boost to start up within a ultra low input voltage and the UVLO of most boost device is 1.8 V or 0.7 V. let along 150 mV. This application note provides a solution using TPS61299 to support the 150 mV ultra low input voltage system.

GUID-20230815-SS0I-VXQL-GWGH-FZN2XM8PWQJB-low.jpg Figure 1-1 Water Heater Control Diagram