650 V Green Mode Buck Switches Combine Efficiency, Scalability

To meet power management challenges, Fairchild Semiconductor developed the FSL306 and FSL336 650 V Green Mode AC Buck Switches. These devices offer burst-mode operation with the low available operating current (250 µA) that helps to reduce standby mode power consumption for increased energy efficiency. Power scalability from 0.5 W to 3 W (FSL306) through the adjustable current limit pin helps simplify designs and reduce design time.

The FSL306 and FSL336 provide higher reliability through rich protection features, such as a Safe Auto Restart Mode. After a fault condition, the switch waits 650 ms before restarting. This feature reduces the stress on the system during a long-term fault, improving system reliability.

These devices combine a PWM controller and a discrete MOSFET in a single package. A high-voltage regulator enables operation without the need for an auxiliary bias winding. Using a built-in error amplifier, the FSL306 and FSL336 provide direct feedback without a shunt regulator. This helps to reduce the overall bill of material cost while saving board space.

Features and Benefits:

·      Built-in avalanche rated 650 V SenseFET; higher avalanche energy at breakdown mode due to vertical DMOS technology

·     Power scalability from 0.5 W to 3 W (FSL306) by using I limit adjustable function pin

·     No-load power consumption: 25 mW at 230 VAC with external bias; 120 mW at 230 VAC without external bias

·     No need for auxiliary bias winding

·     Ultra-low operating current - 250 µA - reduces standby power consumption

·     Fixed 650 ms restart time for safe auto-restart mode of all protection features

In 1,000-piece quantities, list price for the FSL306LRN is 83 cents each; the FSL336LR costs 85 cents each. Delivery is 8 to 12 weeks ARO.