IC family enables tiny cell-phone chargers

Designed for use in ultra-low-cost battery chargers, the LinkSwitch-LP ICs offer a simple energy-efficient replacement for unregulated line-frequency transformers with up to 3 W of output power. Such chargers are commonly sold with products such as cell phones, cordless phones, portable audio players, shavers, and other personal electronics.

Chargers using Power Integrations' LinkSwitch-LP require just 14 components. Features of the design include:

• a clampless design methodology that uses proprietary IC trimming and transformer construction techniques to eliminate RCD clamp circuitry
• primary-side control of charger output voltage and current to eliminate the need for an opto-coupler and associated components
• integrated frequency jitter and a unique filter-fuse input stage to achieve EMI filtering with just one capacitor
• a transformer design that eliminates the need for a Y capacitor
• hysteretic thermal shutdown that removes the need for external thermal protection
• an energy-efficiency technology that complies with all current and proposed energy standards worldwide

LinkSwitch-LP features a 700-V power MOSFET integrated with control and fault protection circuitry on one IC. The input voltage ranges from 85 to 265 Vac and achieve a low no-load power consumption (less than 150 mW at 265 Vac). Lead-free, plastic through-hole DIP-8, and surface-mountable SMD-8 packages are available. Pricing in 1000-piece quantities for the LNK562PN, a 1.9-W part in a DIP-8 package, is $0.45 each.

Complete documentation for the family can be found at www.powerint.com/linklpproduct.htm. A reference design kit, the DAK-85, is also available. It includes a fully tested 6-V, 330-mA charger, an engineering test report and product samples.