ST Releases AC-Switch Gate Driver & Supervisor IC
STMicroelectronics (ST) announced its STCC08, said to be the first solid-state ac-switch driver to integrate switch-supervision, allowing designers to save board space and reduce workload with a straightforward solution for mains-powered devices designed to meet IEC60335-1 and IEC60730-1 safety standards. ST estimates that around 1.4 billion ac switches, which require designers to implement failure protection to meet international product acceptance criteria, are implemented in domestic appliances annually.
In mains-powered appliances and electrical controls, ST claims that using the STCC08 controller will ease the appropriate FMEA (Failure Mode Effect Analysis) process, as the device’s own FMEA was integrated into its design and includes descriptions of 52 cases of failure. The STCC08’s supervisor capability meets IEC60335 by detecting short-circuit or open-circuit failures, as well as diode-mode failure of a solid-state ac switch in both half-ac-line polarities. The device uses what are described as unique techniques to detect true switch status, and generates a logic signal connected to a digital input of a microcontroller (MCU), which implements the diagnostic using a simple two-input truth table. In insulated applications, the STCC08 output is also able to drive an opto-transistor.
The STCC08’s integrated switch gate driver is capable of sinking up to 25mA to drive a directly connected ac switch, and supports continuous, pulsed or angle-phase modes. The output current is regulated using an external resistor. The CMOS-compatible input enables direct connection to the microcontroller.
Designed for connection in parallel with the power path, the STCC08 is said to deliver a robust solution able to withstand EMI fast transients up to 4kV, thereby meeting IEC61000-4-4. The STCC08 can operate from 3.3 or 5V, is offered in a surface-mount ECPOACK® SO-8 package, and is available now at a unit cost of $0.27 in quantities of 50,000.
