DocID026394 Rev 1

5/48

AN4501

List of figures

5

List of figures

Figure 1.

Circuit schematics in boost configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2.

Application schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 3.

Evolution of IL, IL,PEAK, IL,PP with VIN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 4.

Typical waveforms of a boost converter in continuous current mode . . . . . . . . . . . . . . . . . 14

Figure 5.

Converter switching frequency versus RSF value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Figure 6.

Inductor waveforms of a boost converter in CCM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Figure 7.

Inductor current flow during the converter on-time and off-time . . . . . . . . . . . . . . . . . . . . . 19

Figure 8.

A shunt resistor is used to monitor the inductor current during the on-state. . . . . . . . . . . . 22

Figure 9.

Inductor current at the boundary between CCM and DCM. . . . . . . . . . . . . . . . . . . . . . . . . 23

Figure 10.

Typical waveforms of the freewheeling diode in CCM . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Figure 11.

Feedback resistors for output over-voltage detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Figure 12.

Typical current waveforms of the output capacitor current . . . . . . . . . . . . . . . . . . . . . . . . . 28

Figure 13.

Current waveforms of the inductor and of the input capacitor for a boost converter in

CCM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 14.

Current waveforms of the input capacitor for a boost converter in CCM . . . . . . . . . . . . . . 31

Figure 15.

Typical current waveform of M1 in CCM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 16.

Waveforms during the switch-on of M1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 17.

Waveforms during the switch off of M1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 18.

Flowchart for the iterative calculation of the junction temperature of M1 . . . . . . . . . . . . . . 38

Figure 19.

Inductor voltage during the on-phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 20.

Inductor voltage during the off-phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Figure 21.

Typical inductor waveforms in continuous conduction mode . . . . . . . . . . . . . . . . . . . . . . . 42

Figure 22.

Typical current waveform of M1 in CCM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Figure 23.

Typical current waveform of the freewheeling diode in CCM . . . . . . . . . . . . . . . . . . . . . . . 44