SNOAAA8 April   2025 LM74610-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 What is MLPE
    2. 1.2 Why, When, Where Needs MLPE
    3. 1.3 What is Solar Power Optimizer
    4. 1.4 Solar Power Optimizer Working Principle
    5. 1.5 Output Bypass Function of Solar Power Optimizer
  5. 2Traditional Designs of the Bypass Circuit
    1. 2.1 Design 1 - Using P-N Junction Diode or Schottky Diode
    2. 2.2 Design 2 - Using MOSFET
  6. 3New Design of the Bypass Circuit
    1. 3.1 Requirements on Bypass Circuit
    2. 3.2 Using Ideal Diode Controller LM746x0-Q1
    3. 3.3 Challenges of Using Ideal Diode Controller
    4. 3.4 Working Principle of LM746x0-Q1 Reverse Voltage Range Extension
  7. 4Bench Test and Result
  8. 5Summary
  9. 6References

3.3 Challenges of Using Ideal Diode Controller

However, the reverse voltage (VO+ to VO-) across cathode to anode of the ideal diode controller can up to very high as the PV panel or string transient voltage. Especially in some cases that PV panels are used in series with very large input voltage range, which is challenging to design the max input voltage range for the bypass circuit.

The maximum reverse voltage of LM74610-Q1 is limited to 45Vmax (transient). Thus, currently available ideal diode controller devices are not designed for solar panel with rated input voltage up to 80V or 125V.

To sustain this high voltage for any range of low voltage ideal diode controller, a depletion MOSFET Qd, as shown in Figure 3-2, is used to extent the reverse voltage range of the ideal diode controller. The drain of Qd is connected to output VO+, source is connected to the cathode and gate is connected to the anode of the ideal diode controller. Now reverse voltage across cathode to anode is decided by the depletion MOS, while not limited by LM74610-Q1.