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VOLUME -24 NUMBER 6
Publication Date: 06/1/2009
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Special Features: Components and Distribution
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June 2009 Issue
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Leadis Launches LED Driver Family
Sunnyvale, CA — Leadis Technology, Inc. has introduced the LDS8710, an innovative inductor-based, high-efficiency LED Driver that eliminates the expensive external Schottky diode normally used in the rectification loop. The new device is the first in a family of drivers which includes the LDS8716 and LDS8714. The LDS8710/16/14 can drive up to 10, 6 and 4 LEDs in series, respectively, from a single-cell Lithium-Ion battery.
The family of drivers is suitable for applications such as smart phones, portable multimedia devices, personal navigation systems and digital photo frames where battery life, display size, resolution and brightness are critical. Each device in the family has a patent-pending, integrated synchronous rectifier which eliminates the external Schottky diode and the need for complicated and costly isolation FETs. This reduces the bill of material and footprint of the display sub-system, and simplifies the design-in process and time to market of the end product.
The LDS8710 drives up to 10 LEDs with factory-preset maximum LED current values of 20, 25 or 30mA with 1 percent accuracy. This eliminates the need for an external sense resistor and further simplifies the system. Since the LDS8710 family operates at a fixed switching frequency, small low profile passive components (10 - 22 mH inductors and 0.1 mF high voltage ceramic capacitors) can be used, which further reduces the system's bill of material and allows for a thin backlight unit profile. Moreover, the use of the 40-V rated integrated synchronous rectifier makes the efficiency dependent upon only one external component parameter: the inductor DCR. This further simplifies the system design, while simultaneously achieving greater than 83 percent efficiency.
The LDS8710 is a fixed 0.7MHz frequency, current mode, boost converter with internal 40-V rated synchronous rectifier and cycle-by-cycle switch current-limit. The device operates down to 2.5V to accommodate new chemistry Li-ion single-cell batteries or two-cell alkaline batteries. Under-voltage protection disables the part at a threshold of 2.1V.
Thermal shut-down is set at 150°C, above which the boost converter stops switching. Normal operation is resumed when temperature drops below 130°C. Output over-voltage protection prevents system damage if one LED is accidentally disconnected. The EN/PWM pin functions both as logic chip-enable pin with low shut down current (<1µA) and as LED-current PWM control pin. The LDS8710, LDS8716 and LDS8714 are available in a tiny 2 x 3 x 0.8mm 8-pin TDFN package. Samples of the LDS8710 are available now.
Contact: Leadis Technology, Inc., 800 W. California Ave., Suite 200, Sunnyvale, CA 94086-4834
408-331-8600 fax: 408-331-8601 Web:
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