This page shows the value of small size LEDs when used in A19 retrofit lamps. In this application, the PCB placement determines the performance of the system. For example, most manufacturers place the PCB on the widest part of the bulb which means many backlighting or non-lighting class LEDs can be used to obtain the desired lumens. However, with this configuration it is very difficult to achieve omnidirectional light with the PCB at such high position, as can be seen in the graphic on the left. Placing the PCB lower, below the curve of the bulb, makes it much easier to get omnidirectional light output. However, this reduces the size of the PCB which places a premium on the PCB area. This also reduces the size of the heat sink which requires LEDs with a higher efficacy. The omnidirectional lamp on the right is the standard and is the required configuration to achieve Energy Star certification.