Let’s take peek inside another recently-introduced LED T8 replacement lamp for fluorescent tubes: The Philips InstantFit lamp. It produces 1500 lm from 14.5W, for an efficacy of 103 LPW. Its CRI is listed as 83, and it comes in a range of color temperatures, from 3000K to 5000K.
It’s non-dimming. But that may not be a deal-breaker for most people looking to upgrade their soon-to-be-obsolete inefficient T8s (a T8 with efficacy of under 88lm/W) or any T12 fluorescent tube lamps. According to Todd Manegold, Director of LED Lamps marketing at Philips Lighting, 80% of fluorescent ballasts are electronic instant-start ballasts, over 10% are rapid start, and less than 5% are dimming ballasts. Philips went for compatibility with instant-start ballasts; hence the InstantFit’s name. The InstantFit also targets fluorescent lights that must work in cold temperatures, as low as −22F (-30C). The light has a rated average life of 50,000 hours which no fluorescent lamp can even approach at cold temperatures. It’s backed up by a 4-year warranty and sells for about $25 each through Amazon. (Or get them with free shipping in packs of 10).
Fluorescent lights have a real Achilles heel in that they don’t perform well at cold temperatures. This makes them a poor choice for long-term use in parking lots or garages –especially those that have occupancy sensors, where the combination of cold temperatures as well as on-off cycling pack a one-two punch of poor light output at cold temperatures as well as shortened lifetimes.
LEDs, on the other hand, have improved performance at cold temperatures, since heat is the enemy of LED lifetimes.
Philips is quite specific about what ballasts the lamp will work with and maintains an InstantFit ballast compatibility chart (pdf). (Not all of the ballasts listed are Philips; you’ll also see General Electric, Universal Lighting, and Osram Sylvania.)
Fortunately, one of the ballasts listed was the Philips Advantage that I’d bought for my Cree T8 LED lamp evaluation and teardown, so I installed the InstantFit lamps and fired them up.)
They performed as specified. As you’d expect of LEDs, they turned on instantly and with no visible flicker. Their specified CRI is 83, which matched with my reading on the MK350 spectrometer. Here’s the spectral power density chart:
Notably, the R9 value is fairly high: 23. This compares favorably with R9 values you’ll see, for example, in consumer LED light bulbs which are often under 10.
So now let’s pop the cover on the InstantFit and see what its electrical interface looks like, as well as the all-important LED selection and architecture.
The power converter board connects to the LED pc board with a connector, rather than the hand-soldered wires that are so often used in assembled-inChina lamps. (I’m a big fan of connectors to avoid hand-soldering.) The lamp has 60 LEDs, all in one long series string.
The LEDs are about 3mm square, and look like they have a single LED die in the center of the phosphor. (It’s hard to see (below), but the cat’s whisker bond wire in the center goes to just one emitter.)
I assume the LEDs are mid-power, and they seem to be in plastic packages. However, Lumileds doesn’t have an LED that looks like this one: It has no square mid-power LEDs with a square filled-phosphor area.
However, while it doesn’t come close to anything in Lumileds portfolio, it does look a lot like the popular Nichia 757 series component NFSW757D-V1.
Lumileds has been slow in moving to beef up its mid-power LEDs, and since it doesn’t have the 3mm-square package, it looks like it has chosen to go with this Nichia device. The InstantFit lamp produces 1500lm, or 71% of the 2100 lm that the Cree T8 lamp produces, but uses only 60 LEDs compared to the Cree’s 120 LEDs. In addition, the Nichia LEDs use a plastic package, a cheaper component than the Cree’s ceramic.
The 83 CRI of the InstantFit, which is much lower than the Cree’s 90 CRI, is determined by the LED components used. Undoubtedly, one reason for the lower price of the InstantFit is the lower CRI Nichia LEDs, but this was a smart trade-off: Philips knows that the most common use for T8 retrofits is not in homes or restaurants where people are presumably willing to pay more for a high-quality light, but more likely in a warehouse or garage, where 83 CRI is fine and people value the ability of the InstantFit to work in cold temperatures.
Because the InstantFit’s LEDs are all in one giant string of 60 LEDs, it can’t take advantage of using the LEDs themselves as a rectifier as does the Cree lamp. The driver has one large electrolytic capacitor, indicating that the AC power from the instant-start ballast is full-wave rectified and then smoothed with the e-cap. The reverse side of the pc board has the remaining power control components, none of which do any sophisticated power management.
There is one interesting 6-pin IC, but I think it’s just a 2-transistor package (labeled 1Ft below):
The July 1, 2014 deadline is nearing that bans the sale of all T12 fluorescent lamps and many T8s that don’t meet efficacy requirements. In summary, for all those non-dimming overhead inefficient T8s you have in your warehouse, industrial space, or home garage, the InstantFit truly is a drop-in replacement for your Instant-start ballast. It performs well at a good price.