General circuit description

AN3372

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Doc ID 018625 Rev 1

Figure 3.

Inductor current during charge phase

When the PMOS Ls is switched OFF, the current goes into freewheeling mode in the high-

side device.

The voltage across the inductor is:

Equation 2

The current through L in this phase decreases linearly. This circuit is actually a rectifier buck

converter.

Figure 4.

Inductor current during discharge phase

To invert the current in the lamp, the two PMOS work in a complementary way: Hs PMOS is

driven and the freewheeling phase is in the Ls PMOS.

lamp

L

V

V

−

=