Electronica: 90% efficient mains LED driver from Power Intergrations
Power Integrations has introduced a range of single-chip mains LED drivers for loads between 2.5 and 50W with +/-5% current regulation.
Called LYTSwitch, the devices can be wired for isolated and non-isolated operation.
“LYTSwitch delivers tight regulation and high efficiency for tube replacements, high-bay lighting and triac-dimmable bulb applications,” said the firm.
Seven variants cover 12-50W load range, with 2.5-8W minimum load limitation depending on the device. Maximum operating voltage is 132V, so these are not compatible with European mains power.
Power factor correction (PFC) and constant current operation are combined in a single switching stage, and driver efficiency is “more than 90% in typical applications, delivering a power factor greater than 0.95 and meeting EN61000-3-2C requirements for total harmonic distortion [THD],” said the firm. “Optimised designs deliver less than 10% THD.”
Combining PFC and current regulator eliminates the need for a high-voltage electrolytic bulk capacitor – with its inherent size and life-time limitations.
“Accurate primary-side control yields constant current performance with better than +/-5% regulation across load, temperature range and production variation,” said Power Integrations. “Switching frequency of 132kHz means that small magnetics can be used in space-constrained bulb applications, while frequency jittering reduces EMI filter requirements.”
Over-voltage, over-current and over-temperature protection are included.
Both leading-edge and trailing-edge triac dimming is possible “even at low conduction angles, easily complying with NEMA SSL6. Start-up is typically less than 500ms, even when dimmed to less than 10% output”, said the firm. “Bulbs using LYTSwitch ICs will turn on at almost the same dimming angle as it was at turn-off, virtually eliminating pop-on. Dead band in triac dimming is also eliminated as the controller ensures that dimming occurs as soon as the dimmer is operated.”
Samples in eSIP-7C (E package) and eSIP-7F (L package) are available now, and there are several reference designs.Tags: constant current, led, mains, PFC, Power Integrations