Leadis Technology Expands LED Driver Portfolio
At the turn of this century, cell phones have evolved from voice-centric devices to true multi-media platforms. This evolution has caused a tremendous paradigm shift in how these communication devices are used. Whereas only five years ago users would use their cell phones for voice communication, today users exchange text messages, read and write emails, share photos, connect to the Internet, shoot videos and activate integrated GPS-Navigation systems from their cell phones. All of these applications center around the cell phone display: users spend more time looking at the display of their cell phone than talking into it. Cell phones' displays are getting larger, with higher resolution and are much more power hungry. Most of the power consumed by the display is actually drawn by the LEDs that light it up. As LED Drivers chips (like the LDS8830 and LDS8842) control the power drawn by the LEDs, any improvement in efficiency, however small, can bring large benefits to the overall battery life of the cell phone.
In addition to the 1x/1.5x/2x charge pump modes traditionally offered, the LDS8842 and LDS8830 integrate an additional charge pump mode that generates an output voltage equal to 1.33 times the input voltage. Leadis' 1.33x pump mode serves as a higher-efficiency intermediate mode between the 1x and 1.5x modes, resulting in efficiency improvements of up to 10% over traditional offerings. Compatible with input voltages ranging from 2.3V to 5.5V, these devices provide up to 92% efficiency with no added external capacitors as compared to conventional 1.5x charge pumps. Both the LDS8842 and LDS8830 are offered in a 3mm x 3mm package, with the LDS8830 being also available in a tiny 2.5mm x 2.5mm package.
"We're pleased to introduce the second and third members of our new, 1.33x-mode enabled, charge pump LED driver family," said Donato Montanari, Vice President and General Manager of LED Drivers at Leadis Technology. "The higher efficiencies possible with our 1.33x technology provide customers with an additional means to increase battery life for their mobile offerings, enabling product differentiation and an enhanced consumer satisfaction. These devices are offered in extremely small packages that are suitable for today compact cell phone designs, where real estate is at premium."
About the LDS8842
The LDS8842 is a high-efficiency 1x/1.33x/1.5x/2x fractional charge pump capable of driving up to four LEDs at up to 25mA each. LED dimming control is programmable with a one-wire interface enabling current level adjustment from 0.78mA to 25mA. LED channel matching is supported within +/-1.5%, with current accuracy at +/-2%.
Input voltages from 2.5v to 5.5v are supported with efficiency up to 92%. Operation at switching frequencies of 1.3MHz (1.5x mode) and 1MHz (1.33x and 2x modes) enables low noise input ripple and utilization of small external ceramic capacitors. Other product features include soft start and current limiting, thermal shutdown and short circuit protection, and a low current shutdown mode of 1uA max. The LDS8842 is offered in a 16-lead thin QFN 3mm x 3mm package with a maximum height of 0.8mm.
About the LDS8830
The LDS8830 is a high-efficiency 1x/1.33x/1.5x/2x fractional charge pump capable of driving up to three LEDs at up to 32mA each. LED dimming control is programmable with a one-wire interface enabling current level adjustment from 1mA to 32mA. LED channel matching is supported within +/-1.5%, with current accuracy at +/-2%.
Input voltages from 2.5v to 5.5v are supported with efficiency up to 92%. Operation at switching frequencies of 1.3MHz (1.5x mode) and 1MkHz (1.33x and 2x modes) enables low noise input ripple and utilization of small external ceramic capacitors. Other product features include soft start and current limiting, thermal shutdown and short circuit protection, and a low current shutdown mode of 1uA max. The LDS8830 is offered in a tiny 12-lead XQFN 2.5mm x 2.5mm with max height of 0.4mm or in a 16-lead TQFN or 12-lead TDFN 3mm x 3mm package with a max height of 0.8mm.
SOURCE: Leadis Technology, Inc.