Power supply design keeps LCD monitor standby to

powerintegrationstinyswitch-pkSan Jose, Calif. — Power Integrations has released a Design Engineering Report (DER-229) that details the design of a 27-watt power supply for LCD monitors and similar applications.

Based on the company’s TNY380PN power supply, part of the Tiny-Switch-PK product family, the design consumes only 80 mW input power while delivering 30 mW to the system in standby mode. This ultra-low standby consumption ensures that there is ample power available for designers to incorporate remote ON/OFF functionality without exceeding the limits of several OEM PC system integrators, said the company. It also exceeds the 1-watt specification of Energy Star and the mandatory 500 mW requirement of the European Union Tier 2 Ecodesign Directive for Energy-Using Products (EuP).

Power Integrations says the design is more than 80 percent efficient at full load under worst-case conditions. The power supply with a 15 volt main output and 5-volt auxiliary output, includes control regulation functions that minimize power consumption at no load.

The IC also uses frequency jittering to reduce the size of the electromagnetic interference (EMI) filter, eliminating the need for X capacitors and their associated bleed resistors (required for safety compliance), which can themselves dissipate more than 30 mW.

The transformer used in the design was developed using Power Integrations’ PI Expert power supply design software to reduce parasitic losses between windings. High switching frequency at full load suppresses acoustic noise from the power supply and enables the use of very small magnetic components, making the new design well-suited for slim form-factor LCD monitors and similar space-constrained applications.

“By delivering a power supply with a no-load consumption of less than 80 mW, customers can easily meet all known standby power regulations and the most advanced market-driven requirements, while leaving a large power budget available for other circuit functions,” said Andrew Smith, product marketing manager at Power Integrations, in a statement. “The design is also highly efficient in normal operation, enabling PSUs that easily meet full-load efficiency requirements.”

Power Integrations has produced several ultra-low standby power design examples that dissipate as little as 8 mW no load for low-power adapter applications. Visit the company’s new ultra-low standby microsite for more information.