AN2383 datasheet(20/39 Pages) STMICROELECTRONICS

20 / 39 page

Measurements at 50 Hz

AN2383

20/39

Doc ID 12433 Rev 3

5.7

Removing the pot

A pot placed on the plate may be removed at any time, including when the system is

working.

As seen before, the voltage drop present in the VLINK signal determines whether a pot is

placed on the plate or not. The VLINK signal is captured continuously while system is

working.

Lifting the pot up from the plate causes the voltage drop in the VLINK signal to decrease. As

soon as the voltage drop rises over the pot detection threshold (PDT), the MCU recognizes

that the pot has been removed.

The PWM signal is not stopped at once, but smoothly increased until the 50 kHz frequency

is reached, and then stopped. This procedure avoids current spikes on the resonant tank

line and prevents the power stage burning or being damaged.

At this point, the system is still on, without a pot on the plate. The MCU powers on the plate

5 times with a break of 10 seconds between one powering sequence and the other. If no pot

is placed back on the plate during this time, the system returns to standby mode.

This feature is very useful in cases where the user removes the pot and forgets to turn off

the induction cooking system.

AN2383 Datasheet(PDF) 20 Page - STMicroelectronics