LEDs are more and more lighting the way on the global lighting market – to create successful and withstanding applications you have to pay attention to your design – and especially to your capacitors.
It’s always good to exemplify the relevance of your claim with some scientific backup – in regards to the relevance of the LED market we would like to start like this: According to the study 'Global LED Lighting Market (2017 Update)', the LED lighting market which already accounted for almost 60 percent of global lighting in 2016 (worth $47,303 million and growing 18.1% from the previous year), could expand to an $80 billion market by 2020. What it does show (pretty impressively!) is that the LED market is growing – and this growth goes hand in hand with a steep decline in cost per unit, high energy-efficiency ratings and favourable government initiatives driving adoption. Along with the current boom of LEDs in the form of bulb replacement, we can clearly state that LED is the guiding light (yes, we worked very hard on this pun) on the lighting market because of their long life and excellent energy efficiency.
Components for LED lighting design must be selected carefully to ensure that they meet the lifetime and energy efficiency requirements of the end products. These requirements can be demanding – LED lighting products may have an expected lifetime of more than 40,000 hours, for example. Electrolytic capacitors (E-Caps) are commonly used because they are the only capacitors with sufficient energy density to accommodate high power applications and the continuous downward price pressure per unit LED. However, the short lifespan of electrolytic capacitors significantly reduces the lifespan of the entire LED lighting fixture, which is undesirable because it blows out the light of your LED application. Additionally, you have to take into account that most LED applications often have unforgiving operating environments that are not friendly to conventional capacitors, such as aluminium electrolytic (E-caps), causing the electrolyte to evaporate quicker than usual.
But there is a ray of light – it is called OS-CON! OS-CONs are speciality Solid Polymer Aluminium Can-type capacitors that were specifically designed for the demanding high current applications for increasingly dense computing and ICT circuits. In due times, their inherent properties have won electronic designers in industrial, consumer and power segments.
OS-CON models are ideally suited for these applications because they offer a combination of:
- Long Life
- Low ESR
- High Ripple Current
- High Temperature
- High Voltage
- High Capacitance
User Case – how to design your LED circuit with the right capacitors:
A typical LED lighting circuit is shown in the figure below. Besides the safety rated capacitors C1, C2, and C3 (usually films – also available from Panasonic – ECQU and ECWF Series), C8 should be selected to withstand the smoothing of the output. It is this capacitor that dictates the driving input for the LEDs and ensures that no fluctuation occurs that destroys the LED lamp.
On the output side, the voltage ripples need to be minimum to ensure no fluctuation and the OSCONs are especially good here due to their low ESR. As the frequency in lighting applications are being increased to attain various lighting solutions which require changing intensity, dimming and the need to keep lighting pulses at a rate higher than those detectable by human eye. Furthermore, when lighting controls are applied for cascaded or serially connected lighting, it increases the stress on the capacitor in terms of high ripples and higher temperatures. OS-CONs offer also a size advantage as they come in much smaller sizes affording miniaturization of the whole PCB compared to the usually employed Large-can THT which are also a costly option (Can sizes are typically 18mm in height or above).
Panasonic and its OS-CON portfolio:
Your capacitor for high ripple current: The SEPG series of radial lead type conductive polymer aluminium solid capacitors also benefits from very low ESR values of maximum 10mΩ and very stable characteristics at a very wide temperature range from -55°C up to +105°C. SEPG series components have a very long operating lifespan, excellent moisture resistance, and are fully RoHS compliant and halogen-free.
Your capacitor for very high capacitance: The SVF and SEF can achieve 10.000h at 105°C which delivers on the extended lifetime that polymer technology promises. The SVF series offers higher capacitance (1000 uF) and ripple current rating (5 Arms) while the SEF series is even more high-end, packing higher capacitance within the same case size. The components are ideally suited for passing and/or withstanding large slugs of current and can be used for holding a large amount of charge. All the new series are offered in surface-mount and through-hole versions and deliver a value proposition in terms of part count reduction and space limits.
Your capacitor for high voltage and capacitance: New high-end SVPK Series surface-mount type capacitors feature a ripple current range of 1.7A up to 5A ensuring optimal quality even under the strictest requirements. The components are also ideally suited for passing and/or withstanding large slugs of current. The mainstream SVF surface-mount and SEF through-hole-type series offer capacitance values as high as 1000µF (at 16 VDC) ensuring the parts can be used for holding a large amount of charge.
Your capacitor for voltages above 63V: Both radial lead type SXE series components and surface mount type SXV series products are fully REACH and RoHS compliant as well as halogen-free. The components have been designed for an operating temperature range from -55°C up to +125°C, benefit from a voltage range from 63VDC up to 100VDC, a rated capacitance range of 6.8μF up to 68μF, and a capacitance tolerance of ±20% (120Hz / +20°C). The endurance is up to 1000h at +125°C.