SLUAAV9 March   2024 LM76003 , UCC27201A , UCC27282 , UCC27288

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Design and Potential Risk in Certain Application Scenario
  6. 3Analysis of Potential Problem
    1. 3.1 High Duty Cycle Causes High Current Stress in Bootstrap Diode
      1. 3.1.1 Mode 1
      2. 3.1.2 Mode 2
      3. 3.1.3 Mode 3
      4. 3.1.4 Mode 4
    2. 3.2 Influence by the Extra Voltage Source
  7. 4Design Recommendation
  8. 5Summary
  9. 6References

3.1.3 Mode 3

In this mode, Q1 remains turn-off and Q2 gradually turns on. Figure 3-5 shows equivalent circuits in mode 3.

GUID-20240313-SS0I-0LDL-L5BV-5JSMLWKTHVX5-low.svg Figure 3-5 Equivalent Circuit in Mode 3

Assume the input voltage of power stage is VCC. Due to the turn on process of Q2, voltage in HS node can increase rapidly from Vd2 to VCC. So, HB to ground voltage can increase correspondingly. This can let bootstrap diode become reverse bias, a reverse recovery process can happen, reverse current can flow through bootstrap diode. This is the main risk to cause damage with gate driver.