Device simplifies design of industrial supplies for 440VAC line input

Power Integrations has announced a new reference design (DER-479) demonstrating an industrial power supply using the company's LinkSwitch-4TM family of CV/CC primary-side regulated (PSR) switcher ICs with a 1200V bipolar junction transistor (BJT). The design supports 440 VAC line inputs and features three outputs which combine to provide up to 11W of highly-accurate constant-voltage DC power. LinkSwitch-4 controllers feature an adaptive base and emitter switched drive scheme to boost switching performance and increase efficiency. The advanced switching technique is especially beneficial in high-voltage applications as it reduces slow turn-off switching losses and eliminates BJT failures due to secondary breakdown, improving the reverse-bias safe operating area (RBSOA) and system reliability. Additionally, the LinkSwitch-4 controller's primary-side regulated sensing methodology eliminates expensive and unreliable optocouplers, replacing them in the feedback loop with a simple transformer winding. The design uses just 50 mW under no-load conditions while maintaining a fast transient response. The 65kHz operating frequency minimizes transformer size, reducing system cost and PCB footprint. LinkSwitch-4 devices also compensate for a number of factors including: transformer inductance tolerances; input line voltage variations; cable voltage drop; and external component temperature variations. Silvestro Fimiani, senior product marketing manager, Power Integrations, said: "Power supplies for high-voltage systems such as three-phase meters and motor drives can be challenging to develop - efficiency, reliability and component count often suffer in such designs. By pairing the LinkSwitch-4 controller with a 1200V BJT, the designs become very straightforward and extremely reliable." The DER-479 is freely-downloadable from the Power Integrations web site, says the company.