STCC08 STMicroelectronics, STCC08 Datasheet - Page 6

• Manufacturer Part Number: STCC08
• Description: IC DETECTOR AC SW FAILURE 8SOIC
• Manufacturer: STMicroelectronics

Specifications of STCC08

• Applications: Home Appliance
• Current - Supply: 2mA
• Voltage - Supply: 2.97 V ~ 5.5 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Supply Voltage (max): 6 V
• Supply Voltage (min): 0 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 20 C
• Mounting Style: SMD/SMT
• Gate Driver Output: 28 mA max sink current
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Functional description
6/13
Failure mode detection
This function detects AC switch failure modes required by the IEC 60335 standard:
●
●
●
This function improves the system safety. A diode mode failure, a short circuit or an AC
switch open can lead to dangerous situations for the system or the user.
The AVF block monitors the state of the AC switch in both AC polarities. Its output AVF is
transmitted to the MCU for failure detection.
The MCU detects the failure according to the following truth table:
Table 8.
For a diode mode, the AVF output toggles from open collector to GND each the half of the
AC mains. Therefore, the AVF output is a pulsed signal during a diode mode failure.
already existing in home appliance designs.
Status reading
The AVF output is an open collector, active at low level. It can either be connected to a MCU
input, in pull up input configuration, or through an opto-coupler in insulated designs.
For inductive loads, there is a phase shift between load current and AC line voltage. When
the ACS control is removed:
●
●
●
The MCU can put the system in a safe configuration, switching off the front end relay
IN (MCU generated)
The AC switch diode mode failure in both negative and positive AC line polarities
This failure is simulated with a diode placed in parallel with the power switch according
to the IEC 60335-1 standard.
The AC switch short-circuit failure mode, any external shorting and any spurious power
switch turn-on
The open AC switch failure mode
The AC switch - latch structure - still conducts and the AVF is at low level until the next
zero current crossing.
The AVF is at low level until next zero current crossing.
In the worst case, the load current crosses zero close to peak mains voltage. Then the
AVF signal should be read at peak mains voltage.
0
0
0
1
1
STCC08 status truth table with R
Open collector to 0 toggle
Open collector
Open collector
AVF
0
0
SHUNT
in parallel with the load
MCU DIAGNOSTIC
Short AC switch
Open AC switch
AC switch OK
AC switch OK
Diode mode
STCC08