LinkSwitch-HP ICs utilize innovative control algorithms and the properties of the main power transformer and output diode – instead of optocouplers and related feedback circuitry – to determine the amount of power to deliver from the primary to the isolated secondary side. This method dramatically reduces component count, saving space and cost while enhancing reliability. Popularized more than a decade ago with the advent of Power Integrations” LinkSwitch line, PSR is now standard in many low-power applications such as mobile-phone chargers but until now has lacked the constant-voltage accuracy required in higher-power products.
LinkSwitch-HP devices feature a multi-mode control architecture that radically advances the state of the art for PSR, making it a viable approach for power-supply applications from 9 W to 90 W.
Commenting Doug Bailey, vice president of marketing at Power Integrations said: “Power Integrations was first to introduce integrated primary-side off-line switcher devices, and LinkSwitch products currently out-sell any competing PSR technology across a broad swathe of low-power applications from mobile-device chargers to LED lighting to appliance bias supplies and even smart meters. LinkSwitch-HP devices extend the power range of PSR up to 90 W, enabling designers to bring the benefits of PSR to such applications as tablet chargers, ultra-book adapters, LCD monitors and TVs, STBs, appliances and embedded power supplies. LinkSwitch-HP ICs deliver power and performance unequalled by any other PSR solution.”
LinkSwitch-HP devices automatically select their control mode according to prevailing line and load conditions to optimize conversion efficiency and response to transient load demands, while minimizing output ripple and audible noise. Continuous-conduction-mode (CCM) operation results in reduced RMS currents, leading to higher efficiency and less heat dissipation, while 132 kHz, full-load operating frequency enables the use of smaller magnetics and LC post-filter components.
The ICs are capable of no-load power consumption of less than 30 mW at 230 VAC and are more than 50 percent efficient at 0.1 W input power, easily meeting all global energy efficiency regulations such as ErP (EuP), ENERGY STAR(r) EPS V2.0 and EC Ecodesign Directive Tier 2 for external power supplies. The devices also reduce the cost and complexity of meeting Chinese safety standard GB 4943.1-2011, which mandates the use of warning labels on power supplies that do not meet strict creepage and clearance rules.
Similar to UL 60950-2007 and set to become mandatory on December 1st, 2012, the new rule requires designers to increase the primary-to-secondary clearance by a factor of 1.48 for power supplies used in equipment above 2000 m, or else add a warning label to the product.