iWatt Introduces Digital PWM Controller for Low Power ac-dc Adapters and Chargers

iWatt, Inc. introduced the iW1688 primary feedback controller which applies digital control techniques to challenging low power, low cost ac-dc supply requirements. A proprietary combination of sampling techniques and an area efficient digital engine provide a powerful control loop to enable tight regulation and efficient implementation for 2- to 5W ac adapters needed everywhere – from cellular and cordless phones to digital music players and digital still cameras. These adapters can now be smaller, less expensive, and more efficient.

According to Doyle Slack, VP of Marketing, "In an environment of increasing regulatory pressures on ac-dc supplies for low power applications, the iW1688 is a game changing product. It significantly simplifies meeting tighter no-load power requirements while eliminating external components that add both cost and reliability issues, such as opto-couplers. Using the iW1688, customers can easily meet existing and pending requirements such as Energy Star and the California Energy Commission."

The iW1688 implements all of the control functions required to design a low-power supply using primary feedback control. Until now, tight supply regulation required secondary feedback loops that added both components and reliability concerns, which can now be eliminated. The digital control circuitry also allows the integration of additional features including robust over- and under-voltage shutdown and internal constant current control.

The digital control circuit in the iW1688 makes it possible to sense voltage and current on a cycle-by-cycle basis at the full 40kHz operating frequency and make adjustments on each cycle to respond quickly and accurately to load changes or fault conditions. This same control loop also provides internal compensation, eliminating the external components that are normally required, and which add manufacturing cost and design time.

In addition to designing the iW1688 from the ground up for ease of use, iWatt backs it with full applications labs in the US, China and Taiwan. Customers can get real-time support while quickly developing iW1688-based designs that meet their specific power requirements. The iW1688 is fully qualified and in volume production now. Packaged in an RoHS-compliant 5-lead SOT-23 package, the iW1688 is available in 3,000 piece reels, and is priced at $0.31 in 10,000 piece quantities.