STCC02-ED5 Datasheet, PDF (5/13 Pages) STMicroelectronics – CONTROL CIRCUIT FOR HOME APPLIANCE MCU BASED APPLICATION

■ The magnetron relay coil driver
STCC02-ED5
IN2
15 kΩ
DS
Demagnetizing Diode
VDD
MAG2
FAN1
Relay
Transistor
This robust driver interfaces a DC relay coil and an MCU output. The relay coil power is rated up to 1.2 W
for V_CC = 12V.
Its output stage is made of a transistor and a demagnetization diode. The transistor's reference is to the
power ground COM and has a DC current rating of 100 mA. Its collector is connected to the outputs MAG₂.
The diode is connected between the output pin MAG₂ and the Door Switch pin DS.
To enhance safety rules and to prevent any unventilated operation of the magnetron, the relay coil mag-
netization is enabled by the fan conduction state that becomes a logic signal FAN₁\.
Furthermore, its demagnetization node is connected to the door switch pin DS: when the oven door is
open, the coil of the magnetron relay is immediately disconnected from the relay supply V_CC to switch off
these heating loads.
The boolean rule of the magnetron relay operation becomes:
(Magnetron relay ON) = DS.IN₂.FAN₁\.
IN3
50 kΩ
VDD
VCC
1.5 kΩ
BUZ3
Buzzer
Transistor
VCC
Demagnetizing Diode
VDD
IN1
15 kΩ
FAN1
Relay
Transistor
■ Fan relay coil driver
This robust driver interfaces a DC relay coil and an MCU output. The relay coil power is rated up to 1.2W
for V_CC =12 V.
Its output stage is made of a transistor and a demagnetization diode. The transistor is referred to the
ground COM, has a DC current rating of 100 mA; and its collector is connected to the output FAN₁. The
diode is connected between the output pin FAN₁ and the supply pin V_CC.
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