International Rectifier Corp. (IR, El Segundo, CA) announced its new IRISMPS4 reference design for flyback topology, ac-dc power supply circuits found in DVD/CD players, set-top boxes and an array of consumer electronics. Using the IRIS4009 ac-dc integrated switcher as the main switch and control device, the IRISMPS4 reference design features a universal ac line input and 15 V/4 A full-load dc output. The IRIS4009 is suitable for universal and single-input ac-dc power supplies and adaptors for consumer electronics, as well as in larger ac-dc power supplies or motor drives (up to 30 W open frame, or 15 W closed frame).
A dropping resistor from the dc bus initiates startup current for the IRIS4009. Once the circuit is started, the Vcc power for the IRIS4009 comes from the bias winding of the main transformer. The primary current control circuit consists of a current-sensing resistor, which feeds a voltage proportional to the transformer primary current into the feedback pin of the IRIS4009. The secondary voltage control loop uses an LM431 precision shunt regulator as the reference and an optocoupler to feedback the information to the IRIS4009 control circuit.
The IRIS4009 combines a control IC and a low-loss, HEXFET™ power MOSFET in a single five-pin package for ac-dc power supplies up to 30 W. The IRISMPS4 reference design is available now. Pricing is $245 each.