DocID12784 Rev 6

3/35

AN2450

List of figures

35

List of figures

Figure 1.

LLC resonant half-bridge converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 2.

FHA resonant circuit two port model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 3.

Conversion ratio of LLC resonant half-bridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 4.

Shrinking effect of l value increase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 5.

Normalized input impedance magnitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Figure 6.

Capacitive and inductive regions in M - fn plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Figure 7.

Circuit behavior at ZVS transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 8.

Voltage gain characteristics of the LLC resonant tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 9.

Transformer's physical model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Figure 10.

Transformer's APR (all primary referred) model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 11.

Transformer construction: E-cores and slotted bobbin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 12.

LLC resonant half-bridge converter electrical schematic . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 13.

Circuit efficiency versus output power at various input voltages. . . . . . . . . . . . . . . . . . . . . 30

Figure 14.

Resonant circuit primary side waveforms at nominal dc input voltage and full load . . . . . . 31

Figure 15.

Resonant circuit primary side waveforms at nominal dc input voltage and light load . . . . . 31

Figure 16.

Resonant circuit primary side waveforms at nominal dc input voltage and no-load . . . . . . 32

Figure 17.

Resonant circuit primary side waveforms at nominal dc input voltage and light load . . . . . 32

Figure 18.

+200 V output diode voltage and current waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 19.

+75 V output diode voltage and current waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33