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

3.4.1 Why With the Larger Inductance, The Smaller PVIN Start-up Can Be Achieved?

With inductance decreasing, the power converting to the output side is increased due to the smaller slope of inductor current , as is shown in Figure 3-6.

Therefore, according to the Equation 3, under the condition that ton < ton _max, AVIN and VOUT are the same, the larger L is, the smaller di/dt is. Then the more energy can be stored during the ton period and the more energy will be converted to the output during the toff period. Therefore, with larger the inductance, lower PVIN startup can be achieved.

GUID-20230822-SS0I-LQPS-JVB2-9BQFFBPWT7XG-low.svg Figure 3-6 Inductor Current With Different L