ROHM’s High Luminous Intensity White LEDs Come in a 1608 PackageApril 29, 2021 by Gary Elinoff
The new white chip LEDs sport a 2.0 cd intensity in a tiny 1.6 by 0.8 mm package.
The CSL1104WB series from ROHM are optimized for applications where high brightness white light emissions are required.
The CSL1104WB. Image courtesy of ROHM
While competitive white chip LEDs are offered in 3.5 x 2.8 mm 3528 packages, the CSL1104WB is 87% smaller, while still putting out 2.0 cd. This is a key advantage. Many devices now entering the market need a lot of white light concentrated in small spaces, and the far smaller ROHM devices are better suited to the high density mounting that will be required.
Specifications of the CSL1104WB Series
The CSL1104WB devices’ chip structure is InGaN. The units dissipate a maximum of 144mW.
Maximum forward current is 40mA, with a peak current of 100mA (10% duty cycle @1kHz). Maximum reverse voltage is 5 volts. All members of the series feature a Directivity Angle of 115°. Compared to the base value at 25℃, luminous intensity increases by almost 10% at -40℃, while decreasing by slightly more than that amount at 100℃
As illustrated in the datasheet, at 25℃ and at 2.6 volts, forward current is zero, while at 3.1 volts, forward current is roughly 40 mA. All members of the CSL1104WB series draw 20 mA at a forward voltage of 2.9 volts.
The Individual Members of the Series
There are four members of the series. The chromaticity distribution for each is illustrated below
Chromaticity distribution for each member of the CSL1104WB series. Image courtesy of ROHM
Color adjustment is simplified by fine grained, accurate white color chromaticity. Color variability, always an issue with LEDs, is much improved in the new series. The process of color adjustment is simplified through the achievement of color uniformity. This can serve to reduce the amount of effort required for application development.
Typical Chromaticity Coordinates
The brightness figures above are for LED forward voltages of 2.9 volts.
High Brightness for Cleaner Design
With weaker LEDs, light leakage compromises the integrity of LED-light displays. In the top portion of the image below, the weakness of conventional LED illumination forces the use of cover materials with higher transmittances. The result is that even with the LED turned off, at certain viewing angles now an unintended message will be visible.
Image courtesy of ROHM
As illustrated in the lower portion of the figure, with the powerful 2 cd CSL1104WB, a cover with less transmittance is possible, and when the device is turned off, complete blackout of the message is attained.
Planning for the Future
The AEC-Q102 is the automotive standard specifically developed for optical devices. Qualification to this standard is planned, enabling a smooth transition to new vistas.
ROHM also plans to consolidate its entire luminous intensity lineup to the 1608 size.
The CSL1104WB operates over a -40 to +110℃ temperature range. However, the maximum forward current of 40 mA begins to derate at temperatures greater than 75℃.