Datasheet

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March 2008 Rev 1 1/13

STCC08

AC switch failure mode detector

Features

■ 3.3 V and 5 V power supply compatible

■ ACS, ACST, TRIAC compatible

■ Gate driver output: 28 mA max sink current

■ Adjustable gate drive current

■ Sense the AC switch voltage in both AC line

polarities

■ Diode mode failure detection for solid state AC

switches

■ Short circuit failure detection for AC switches,

relays, electromechanical switches

■ Open AC switch detection for AC switches,

relays, electromechanical switches

■ SO-8 SMD package

Benefits

■ Enable appliances to meet IEC 60335-1 and

IEC 60730-1 standards

■ Enable appliances to meet IEC 61000-4-4

standard

■ Eliminates high DC current in inductive load, by

detecting the diode mode failure

■ Improve system safety monitoring open switch

failure with critical loads such as door locks

■ Enable MCU to sense all AC switch failure

modes and protect the appliance

■ Less MCU pin allocated to AC failure detection

multiple STCC08 designed with resistor

dividers uses one I/O

■ Easy to drive with MCU directly connected or

through an opto coupler

■ Highly compact with integrated solution in SMD

version

Applications

■ Home appliances

■ ACS, ACST, TRIAC drive

■ AC switch failure modes detection

■ Zero voltage synchronization

Description

The STCC08 is an AC switch failure mode

detector and an AC power switch driver. It drives

the AC switch and informs the MCU of switch

failure. The MCU takes the appropriate actions to

put the system in a secure state.

Diode-mode, short circuit detection and open

switch in both AC line polarities are detected.

The STCC08 helps home appliances to meet the

IEC 60335-1 safety standard.

The STCC08 can be easily interfaced to an MCU

with its CMOS input AC switch driver and CMOS

compatible output for the failure mode detector.

SO-8

www.st.com

Summary of content (13 pages)

PAGE 1
STCC08 AC switch failure mode detector Features ■ 3.
PAGE 2
Characteristics 1 STCC08 Characteristics Figure 1. Circuit block diagram GATE DRIVER G IN + RIG VCC AVF AVF DRIVER AC POWER SWITCH SIGNAL SHAPING Table 1.
PAGE 3
STCC08 Characteristics Table 2. Pin allocations Pin # Name 1 IN 2 AVF Alternating voltage feedback: AC switch status output 3 N/C Not connected 4 AC AC switch status sense input 5 VCC Positive power supply 6 G 7 RIG 8 GND Table 3.
PAGE 4
Characteristics STCC08 Table 5. Electrical characteristics Symbol Pin Name Conditions Min Typ Max Unit Switch drive (respect to GND, Tj=25 °C unless otherwise specified, RIG=30 Ω) IQUIESCENT VCC Quiescent current IN = GND VON IN On-state switch activation voltage VOFF IN Off-state switch release voltage IIN IN Input drive current Vin > Von IG G Gate drive current Vin > Von IAC AC Detection threshold 2 mA V 0.7*VCC 0.
PAGE 5
STCC08 2 Functional description Functional description STCC08 functional description The STCC08 is a power circuit designed to drive up to 10 mA IGT AC switches and to detect AC switch failure modes through MCU diagnostic. It embeds a logic switch driver, an AC switch diode mode detection, a short circuit detection and an AC switch open detection. STCC08 can be powered by a 3.3 V or 5 V power supply voltage.
PAGE 6
Functional description STCC08 Failure mode detection This function detects AC switch failure modes required by the IEC 60335 standard: ● 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.
PAGE 7
STCC08 Functional description Figure 4. Failure mode detection for inductive loads in DC control mode NORMAL MODE SHORT CIRCUIT DIODE MODE AC LINE LOAD CURRENT IN AVF SUGGESTED READING TIME NORMAL MODE SHORT CIRCUIT DIODE MODE The microcontroller can store the AC switch drive signal in a RAM register when it is driving the STCC08 input. Therefore it can save gate energy while determining conduction state from this RAM register and multiplexing this information with AVF signal.
PAGE 8
Application information 3 STCC08 Application information Figure 5. Application example with an MCU direct drive + ACS 3.3V to 5V NEUTRAL VCC GATE DRIVER G IN + RIG RIG ACS VCC RSHUNT RAC VCC AVF DRIVER LOAD AVF AC SW POWER SWITCH SIGNAL SHAPING GND MCU LINE The placement of a 100 nF capacitor between VCC and GND close to the STCC08 is advised. SW is an electromechanical switch that is part of the application design, for example, the water sensor in a washing machine. 3.
PAGE 9
STCC08 Application information This function is effective whatever the drive and the nature of the load. Figure 7. ACS benefits VCC NEUTRAL G VMAX = V CL ACS RAC1 RAC2 AC The ACS clamping capability, from 800 V to 1100 V reduces the stress across RAC resistors during an AC line over-voltage. This provides a robust solution and allows setting high voltage resistors RAC to withstand the ACS clamping voltage instead of the AC line maximum over-voltage. STCC08 AVF alarms configuration Figure 8.
PAGE 10
Application information Table 9. STCC08 STCC08 status truth table with RSHUNT removed IN (MCU generated) AVF MCU DIAGNOSTIC 0 Open collector AC switch OK 0 Open collector to 0 toggle Diode mode 0 0 Short circuit or open lead 1 0 AC switch OK 1 Open collector Open AC switch STCC08 ZVS application Figure 9. ZVS application schematic NEUTRAL 3.
PAGE 11
STCC08 4 Package information Package information ● Epoxy meets UL94, V0 In order to meet environmental requirements, ST offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an ST trademark. ECOPACK specifications are available at www.st.
PAGE 12
Ordering information 5 Ordering information Table 11. 6 Ordering information Order code Marking Weight Base Qty Delivery Mode STCC08 STCC08 0.08 g 100 Tube STCC08RL STCC08 0.08 g 2500 Tape and reel 13” Revision history Table 12. 12/13 STCC08 Document revision history Date Revision 20-Mar-2008 1 Changes Initial release.
PAGE 13
STCC08 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale.