Power conversion ICs from Power Integrations cost-effectively replace the inefficient passive supplies that typically power the electronic controls found in home appliances and industrial equipment. The 3-chip LinkSwitch TN family offers a monolithic high-voltage power conversion IC designed to build nonisolated, low-current (up to 360 mA) switching power supplies. These switching supplies are meant to supplant capacitive dropper and linear transformer power supplies. The LinkSwitch TN delivers the benefits of a switcher— small size, light weight, good regulation, and high energy efficiency—at system costs equal to or lower than the older technologies.
Requiring as few as 15 standard components, a single LinkSwitch TN IC provides a universal-input, energy-efficient switcher design in a buck or buck-boost configuration. These designs achieve +/-10% load regulation. Moreover, standby power is very low: A typical ac-dc buck converter built with LinkSwitch TN will consume less than 100 mW in the no-load condition.
The CMOS chips integrate a 700-V power MOSFET, an oscillator with simple on/off control, and high-voltage start-up circuitry. Other functions include current limiting, hysteretic thermal shutdown and auto-restart. The LinkSwitch-TN devices come in either a plastic DIP-8 or an SMD 8. Unit pricing in 10,000-piece quantities for the DIP-packaged chips ranges from $0.42 for the smallest device (the 170-mA LNK304P) up to $0.59 for the largest device (the 360-mA rated LNK306P).
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