The latest generation of off-line switcher ICs has ben releasby Power Integrations in its TinySwitch family.
The TinySwitch-4 devices feature line-compensated overload power protection, are capable of potentially reducing the maximum overload power that can be delivered into the load over the entire AC input voltage range.
The devices combine a clever mix of technologies including a 725 V MOSFET that easily allows 80 percent de-rating for high reflected voltage and high bus-voltage designs. Efficiency of greater than 70 percent at five percent load enables designers to meet the stringent European standby specifications scheduled to take effect in 2013, while no-load power consumption of less than 30 mW at 230 VAC meets critical energy-saving requirements in the market today.
The line-compensated overload power protection of these ICs is particularly helpful in applications such as PC standby and appliances where unusually high current demands from the load may be indicative of a fault. Prompt action by the power supply to limit the current to a designed maximum value may prevent damage to the circuitry and enhance overall system safety and reliability.
The BP/M pin permits the MOSFET current limit to be adjusted up or down, allowing designers to optimise power delivery and efficiency in a variety of physical implementations. An on-time extension function extends the low-line regulation range, enabling hold-up time to be met with lower values of input capacitance.
These devices also feature latching output overvoltage protection (OVP) configurable for fast AC reset by connecting the EN/UV pin resistor to the AC input line. Improved auto-restart ensures that power delivery during an output fault is limited to less than 3 percent of full load rating.
The family of devices are a scalable covering an extended power range up to 36.5W, including such power-supply applications as PC standby and other auxiliary supplies, DVD/PVR and other low-power set-top decoders, appliances, industrial systems, utility meters, and chargers/adapters for mobile and cordless phones, digital cameras, portable audio, etc.
Three package options are available: the industry standard PDIP and SOIC packages, and the new SMD eSOP package which enables designers to eliminate external heatsinks, instead using PCB copper area for thermal dissipation.
Power Integrations, Inc.
