Datasheet

CH3 = Current Sense = V@R13

CH4 = Primary Transformer Current

CH2 = Switch Node = Q2

CH1 = Switch Node = Q2

Gate Drive Transition After Switch Node Achieving ZVS

Test Data

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9.4 Zero Voltage Switching

One of the major benefits of a LLC resonant half-bridge converter is the ability to achieve Zero Voltage

Switching (ZVS) at the primary switch node. Figure 10 shows the primary transformer current (CH4), the

current sense voltage (CH3), the switch node on the primary at the drain of FET Q2 (Q2g) and the gate

drive signal to FET Q2 (Q2g). The gate drive signal going to FET Q1 is the inverse of CH1. From the

waveform in Figure 10 it can be observed that the gate drive signals do not transition until after the switch

node has transitioned achieving zero voltage switching.

Figure 10. V

= 390 V, Outputs Loaded with 32, Cree XLamp CR-E , LEDs

98-W Resonant LLC, 4-String LED Driver SLUU487A–March 2011–Revised March 2011

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