Sylvania LED9A19/DIM/O/827/U/ZH LED bulb

The Sylvania LED9A19/DIM/O/827/U/ZH bulb is rated at 9w and 800 lumens light output equivalent to a 60W incandescent bulb. There are 16 upward facing LEDs mounted on an aluminum-backed PCB which is screwed to an aluminum heat sink disk. The heat sink/PCB assembly is pressed into an additional aluminum heat sink within the A19 base.

A single sided printed circuit board inside the A19 base provides AC to DC conversion. On one side of the board larger through-hole components such as inductors and capacitors are located. On the other printed side the surface mounted components are located. The semiconductor content of this product consists of a diode bridge, a switching diode and a Bright Power Semiconductor BP3212 controller in an 8-pin package. The AC to DC conversion circuit connects to clips on the LED assembly through two wires.

The circuit is a non-isolated buck-boost converter that generates a DC voltage for driving the LEDs from the full wave rectified 120 volt AC input. The rectified AC is not directly filtered to an intermediate DC voltage because this would require a large capacitor. Instead, the full wave rectified AC voltage varying from 0 to approximately 170 volts peak is fed through a passive LC filter to block high frequencies and provided directly to the switching regulator consisting of an inductor, diode, a large electrolytic output capacitor, and the BP3212 which includes a power MOSFET switch. Although the switching inductor looks like a transformer and is labeled as "T1", it has only 3 pins of which one has no electrical connection and is used only to provide mechanical stability. Transient protection is provided by a 270v varistor and 20 ohm fuse resistor at the AC input.

A polar coordinate graph shows the light intensity of the Sylvania LED9A19/DIM/O/827/U/ZH at 4 different power levels adjusted with a triac dimmer. 0 degrees is the top of the bulb and 180 degrees is the base of the bulb where the light is completely blocked. Full power intensity is somewhat asymmetric with a maximum of 4500 lux at -60 degrees and sharp drop offs at +90 and -120 degrees. The asymmetry may be the result of non-uniform placement of LEDs on the upward facing disk. Integrating intensity over the entire surface gives a total light output of 670 lumens, short of the rated 800 lumens. However a 60W incandescent light bulb provided only 400 lumens under the same measurement conditions so there is probably a significant calibration error. Power consumption was measured at 9.2 watts, slightly exceeding the rated power consumption. Energy efficiency of the bulb can be calculated by converting lumens to watts on the basis of the photopic luminosity function (683 lumens/watt) which approximates the range of wavelengths visible to the human eye at normal intensities. The Sylvania LED9A19/DIM/O/827/U/ZH efficiency in converting electrical power to optical power at visible wavelengths is calculated at 10.7% under full power. For comparison the 60W incandescent bulb is calculated at only 1.0% efficiency.