Other Functions; Pan Detection; Buzzer And Fan Control; Figure 2-8 Buzzer And Fan Control - Samsung S3F84B8 Design Manual

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00

2.6 OTHER FUNCTIONS

2.6.1 PAN DETECTION

Pan-on detection is executed every 2sec when the system is idle. It is useful when you press the Start key first
and then put the pan on. In principle, even though the IGBT is turned on, there will not be any oscillation before
the pan is put on the panel. In S3F84B8, comparator 0's output can be set as the clock source of Timer C. After
starting 1-cycle PWM output and waiting for about 3 oscillation cycles, if TCCNT>1, Pan status = on; else Pan
status = off. Pan-remove detection is executed every 1.5s when the system is working. It is useful when you
directly remove the pan from the panel without pressing the Stop key.
Pan-remove detection is done by current measurement, that is, when the sensed current is small, the system
considers the pan as removed and turns idle.

2.6.2 BUZZER AND FAN CONTROL

Figure 2-8 shows the circuit diagram for buzzer and fan control.
The fan cools down the system while heating. Buzzer indicates error and key actions.
In Figure 2-8, buzzer and fan share the same I/O. Due to C24, the DC signal controls fans on and off, while
square wave with high frequency determines the buzzer's beep.
Note that C24 cannot be too large; else it will deteriorate the power of MCU and make the integrated analog
modules work unstably.
C24 104M/50V
BUZ/FAN
+18V
R26
1K
Q3
8050
Figure 2-8 Buzzer and Fan Control
2-13
2 HARDWARE IMPLEMENTATION
BUZZER1
CN3
1
2
FAN