SLVAE57B February   2021  – October 2021 LM5050-1 , LM5050-2 , LM5051 , LM66100 , LM74202-Q1 , LM74500-Q1 , LM74610-Q1 , LM74700-Q1 , LM74720-Q1 , LM74721-Q1 , LM74722-Q1 , LM7480-Q1 , LM7481-Q1 , LM76202-Q1 , SM74611 , TPS2410 , TPS2411 , TPS2412 , TPS2413 , TPS2419


  1.   Trademarks
  2. Introduction
  3. Reverse Battery Protection
    1. 2.1 Reverse Battery Protection with Schottky Diode
  4. ORing Power Supplies
  5. Reverse Battery Protection using MOSFETs
    1. 4.1 Reverse Battery Protection using P-Channel MOSFET
    2. 4.2 Input Short or supply interruption
    3. 4.3 Diode Rectification During Line Disturbance
    4. 4.4 Reverse Battery Protection using N-Channel MOSFET
  6. Reverse Polarity Protection vs Reverse Current Blocking
    1. 5.1 Reverse Polarity Protection Controller vs. Ideal Diode Controller
    2. 5.2 Performance Comparison of P-Channel and Reverse Polarity Protection Controller Based Solution
  7. What is an Ideal Diode Controller?
    1. 6.1 Linear Regulation Control Vs Hysteretic ON/OFF Control
    2. 6.2 Low Forward Conduction Loss
    3. 6.3 Fast Reverse Recovery
    4. 6.4 Very Low Shutdown Current
    5. 6.5 Fast Load Transient Response
    6. 6.6 Additional Features in Ideal Diode Controllers
      1. 6.6.1 Back-to-Back FET Driving Ideal Diode Controllers
      2. 6.6.2 Very Low Quiescent Current
      3. 6.6.3 TVSless Operation
  8. Automotive Transient protection with Ideal Diode Controllers
    1. 7.1 LM74700-Q1 with N-Channel MOSFET
    2. 7.2 Static Reverse Polarity
    3. 7.3 Dynamic Reverse Polarity
    4. 7.4 Input Micro-Short
    5. 7.5 Diode Rectification of Supply Line disturbance
  9. ORing Power Supplies with Ideal Diode Controllers
  10. Integrated Ideal Diode Solution
  11. 10Summary
  12. 11References
  13. 12Revision History

Diode Rectification of Supply Line disturbance

Fast reverse current blocking and fast reverse recovery capability of Ideal Diode Controllers help in active rectification of the AC disturbance by turning on and off every cycle. The Ideal Diode controller detects reverse current flowing back into the supply during the test and turns OFF the GATE quickly thereby reducing the RMS value of input current by half. Power dissipation in the MOSFET during the test is reduced due to low forward voltage drop. Figure 7-5 shows the performance of LM74700-Q1 during supply line disturbance or the AC superimposed test.

GUID-3BE484CD-240E-4185-BB37-82F8DD685B37-low.gifFigure 7-5 LM74700-Q1 AC Superimposed Test

Faster turn on and turn off speed of ideal diode gate drivers such as that of LM7472x-Q1, enables active rectification during AC superimpose scenario defined by ISO16750 and LV124, E-06 tests. Active rectification during AC superimpose performance results in lower ripple current and thus enables low power loss across external MOSFET and output electrolytic capacitors.

In the design of mild-hybrid vehicle power trees, the frequency applied during ACS can be up to 200 KHz so as to tailor it to the ripple of the craw-pole Lundell alternator. Hence, the protection device used with DC-DC converters need to be insensitive to frequencies up to 200KHz. Key performance features such as very low forward voltage drop, fast gate drive, fast reverse recovery response and integrated boost converter enables the LM74722-Q1 ideal diode controller to achieve active rectification of AC voltage ripple up to 200 kHz.