Samsung S3F84B8 manual Other Functions, PAN Detection, Buzzer and FAN Control

S3F84B8_ALL-IN-ONE IH COOKER_AN_REV 0.00 2 HARDWARE IMPLEMENTATION

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.

BUZ/FAN

	C24		104M/50V		BUZZER1
+
		+18V
R26			1	CN3
1K			2
			Q3
				FAN
			8050

Figure 2-8 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.

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