Engineer experience: Applications that do not require dimming do not use electrolytic capacitors.

For applications that do not require dimming, the use of LinkSwitch-PH can eliminate the need for electrolytic capacitors. Our single-stage PFC/constant current design allows the designer to eliminate the bulk capacitors that are typically required between the PFC and constant current stages in traditional designs. The only remaining requirement for capacitors is to power the LEDs at the output through the low point of the AC waveform (where the voltage is close to zero). The electrolytic capacitors can be replaced with ceramic, tantalum, or OSCON capacitors of sufficient value to eliminate 100Hz or 120Hz flicker. For high temperature, high reliability industrial applications where dimming is not a concern, I strongly recommend designing without electrolytic capacitors.

Market demands for LED lighting power supplies vary by application. For example, the design requirements for consumer light bulbs are very different from those for streetlights or industrial fluorescent replacement lamps. But in general, all customers need reliable, energy-efficient LED driver products. Other requirements include power factor correction (PFC), flicker-free thyristor dimming, high-precision constant current drive output at different input voltages, temperatures and between bulbs, and consistent turn-on and turn-off performance. The devices launched by Power Integrations (PI) have these features in both LinkSwitch-PH (isolated) and LinkSwitch-PL (non-isolated) topologies, depending on the mechanical isolation method selected and the safety regulations applicable to the target application.

The two-stage architecture is suitable for older drivers that must use a second constant current drive circuit to enable the PFC to drive the LED constant current. These designs are outdated and no longer cost-effective, so a single-stage design is preferred in most cases.

Physical design determines whether the driver is isolated or non-isolated. Safety regulations often require the use of two separate isolation layers. Designers can choose between two physical isolation layers – a plastic diffuser and a glass shield – and use a non-isolated power supply. Alternatively, if physical isolation is too costly, mechanically difficult, or absorbs too much light, electrical isolation must be addressed in the power supply. Isolated power supplies are typically larger than non-isolated power supplies of the same power level. Lighting designers must perform a lot of cost and design optimization work in each product they design.

The main challenge for domestic manufacturers will be how to optimize quality costs, which is one of the basic requirements of LED lamps. Today, a large number of small companies have entered the LED lighting business, and market prices are constantly falling due to competition. Using high-quality, high-reliability power supplies in systems with limited space and heat dissipation difficulties (such as LED lamps) will no longer be free; however, it is quite difficult to prove the high quality of a certain bulb with a life of about 10,000 hours until the end user has used many of them. Things will be much simpler if you use a drive controller company that has a reputation for producing high-quality power products for harsh environments (such as home appliances and electricity meters).