A new family of power-supply (PS) controller ICs supports supplies with peak-to-continuous power ratios of up to 3:1. This would make it possible to build supplies with less expensive components for applications such as printers, whose motors introduce steep, momentary power spikes when a job is initiated.
For example, an inkjet printer that uses 30 W during printing might require a burst of up to 80 W when the paper-advance motor goes into action. Other potential applications include personal video recorders (PVRs), audio amplifiers, broadband modems, and dc motor drives. Power Integrations' PeakSwitch ICs provide a burst of power by momentarily increasing switching frequency. Supplies can be designed with the same transformers, capacitors, and other components that would require the average continuous power level. Each PeakSwitch has a 700-V MOSFET and low-voltage control circuitry on a monolithic IC.
To meet energy-efficiency standards, the chips' simple ON/OFF control provides low stand-by power consumption and constant active-mode efficiency. (Current ramps to a fixed current limit every ON cycle, so each ON cycle delivers fixed energy. Cycles are disabled as necessary to maintain regulation.) Other integral features include auto-restart, hysteretic thermal shutdown, and frequency jittering to minimize electromagnetic interference.
The first parts in the family are the PKS604PN, rated for 16 W continuous, 44 W peak, and the PKS606YN, rated for 45 W continuous, 86 W peak. The lower-power parts are available in lead-free DIP-8, SMD-8, and TO-220 packages. The PKS604PN costs $0.91 in 1000-unit lots. Housed in TO-220 packaging, the PKS606YN costs $1.65.