Leadis Technology, Inc. (Nasdaq: LDIS), an analog and mixed-signal semiconductor developer of color display drivers, Power Management and Touch Sensor ICs for mobile consumer electronic devices, announced sample availability of the LDS8160, a new LED driver featuring its proprietary LED-Sense[TM] Temperature Compensation engine and its patent-pending PowerLite[TM] Current Regulator. The former monitors the in-situ temperature on each LED and independently optimizes the LED current for best luminosity vs. temperature performance. The latter ensures a low drop out voltage on each LED channel of typically 25mV across the full operating current range. To minimize standby current, the LDS8160 also features an additional low-power standby mode, where the supply voltage of the device is switched to 1.8V. The LDS8160 is controlled though a high-speed I2C interface. Targeted at mobile backlighting applications, the LDS8160 supports up to six white LEDs or up to two RGB LEDs, with a maximum current of 25mA per channel.
Mobile phones have evolved from voice-centric devices to multi-media platforms. Whereas five years ago users would use their mobile phones primarily for voice communication, today users exchange text messages, read and write emails, share photos, connect to the Internet, record videos and activate integrated GPS-Navigation systems from their mobile phones. These applications all center around the mobile phone’s display. Consequently, the user expectations in terms of display-performance have increased. For example, users now expect excellent outdoor display readability, which is a challenge given the current required to drive the backlight unit to satisfactory display contrast and color saturation. One solution to this problem is to utilize RGB diodes in the backlight unit. These diodes require temperature compensation in order to keep their white color coordinates constant, a problem that the LDS8160 is designed to solve.
The LDS8160 offers superior temperature control through its proprietary LED-Sense[TM] Temperature Compensation engine. Existing solutions either place a sensor in the proximity of the LED’s, which increases cost and reduces the available footprint of the phone, or rely on measuring temperature only inside the LED driver chip, which can result in inaccurate current readings. The LDS8160, however, measures the temperature of each LED at the diode itself. This in-situ measurement doubles the accuracy and does not require extra sensor components on the board. Every few seconds, the measured temperature is fed into Leadis’ proprietary compensation engine that adjusts the current on each LED channel in order to optimize luminosity, color saturation and to prevent system overheating. Sixteen I2C-programmable registers for each of 3 channel banks let users define the compensation curve as a function of the specific LED Diode used in the design.
The LDS8160 offers multiple advantages for designers of portable applications. For longer battery life, efficiency is increased up to 98% by the inclusion of the PowerLiteTM Current Regulator and the exclusion of boosting circuits that are not needed with most of today LED’s. The ultra low dropout PowerLiteTM Current Regulator provides a transition threshold of 25mV, allowing customers to adopt any LED with a Vf lower than 3.4V. For improved dynamic brightness control, three 12-bit logarithmic PWM generators are integrated on chip. These generators allow customers to send a dimming command through the I2C interface without having to keep “pulsing” a PWM bus. This innovation dramatically improves the power consumption of the system, especially if frequent dimming is required. The LDS8160 is offered in a tiny 3mm x 3mm 16-pin TQFN package and in an ultra small WCSP 3×4 ball grid package with 0.4mm pitch.
“We are pleased to bring to the market our first LED Driver featuring our proprietary Temperature Sensing and Compensation Engine,” said Donato Montanari, Vice President and General Manager at Leadis Technology. “Whereas the LDS8160 is tailored specifically for the mobile market, our Temperature Sensing and Compensation Engine is an extremely accurate and flexible IP block that can be ported across different application markets. We are expecting to introduce temperature compensated devices for the notebooks market soon. With increasing customer demand for improved outdoor readability, the ability to control backlight unit temperature in a dynamic, accurate and fast manner gives mobile phone designers more flexibility in tackling this challenging problem.”
About the LDS8160
The LDS8160 is a dual-output RGB or 6-channel white LED driver with three integrated temperature compensation circuits for each bank of two LED drivers. It can support both RGB LED and WLED backlighting, keypad, and other lighting functions in portable applications. Three programmable, 8-bit DACs set the current level for each LED bank (A, B, & C) from 0 to 25mA in 0.125mA steps. Each channel contains a linear LDO current regulator (driver) in a common cathode (i.e., current source) topology. The LDO drivers have a typical dropout voltage of 25mV at maximum rated current. This provides a low power/low EMI solution in Li-ion battery applications without voltage boosting and associated external capacitors and components. Three 12-bit PWM generators with “smooth” logarithmic control support Temperature vs. LED Luminosity adjustments, as well as RGB color correction and dimming. These PWM generators are programmable via an I2C serial interface. User programmed 8-bit codes are converted to 12-bit resolution logarithmic steps of ~ 0.17 dB per step. The PWM frequency is ~280 Hz to minimize noise generation.
About Leadis Technology, Inc.
Leadis Technology, Inc., headquartered in Sunnyvale, California, designs, develops and markets analog and mixed-signal semiconductors that enable and enhance the features and capabilities of portable and consumer electronics devices. Leadis’ product offerings include color display drivers, which are critical components of displays used in mobile consumer electronic devices; LED drivers, which provide controlled levels of current required to drive light emitting diodes in diverse applications including mobile backlight units; power management ICs including LDOs, LDO controllers, shunt references, thermal switches, current regulators, and battery charger controllers; and touch controller ICs, which enable highly reliable touch-based input controls and attractive industrial design options for both mobile and non-mobile applications.