It's reported that Leadis Technology Inc. is delivering samples of the LDS8845 and LDS8846, no-noise, highly efficient 4-channel white LED drivers targeting handsets and portable products that use lower-VF white LEDs and lower-cost TFT-LCD modules.

According to Leadis Technology, lower-VF white LEDs make it easier to maintain LED current absolute accuracy and channel-to-channel match by eliminating the need for an internal boost converter to increase the driver's output voltage. Eliminating the need for dual-mode (1x/2x) or tri-mode (1x/1.5x/2x) charge-pump boost converters reduces system cost by eliminating up to two ceramic capacitors required by the boost converter, Leadis said.

All products in this family will offer part-to-part LED current accuracy better than 7.5 percent and channel-to-channel matching better than 3 percent—an improvement of at least 25 percent over alternative dual-mode and tri-mode charge-pump based white LED drivers, according to Leadis. In addition, both products offer true-load disconnect in shutdown, output overcurrent protection, thermal shutdown protection, and a 100kHz-rated LED current control interface for those applications where it is desirable to minimize or eliminate audio band noise injection.

To achieve 98 percent efficient operation from a single-cell Li-ion battery, the design of the LDS8845 and the LDS8846 implements Leadis' proprietary, ultralow voltage dropout PowerLite Current Regulator (PCR) technology that maintains current-sink threshold voltages below 50mV.

Packaged in 0.8mm high, 3mm x3mm 16-lead TQFN packages, the LDS8845 operates from 2.7V to 5.5V. A 15.8kΩ resistor sets the LDS8845's full-scale LED output current to 30mA per channel and allows the system designer to program the full-scale LED current to lower full-scale levels, if desired. A two-wire interface is provided to program the four LEDs as a single group or individually; in addition, the control interface can accept a pulse-width modulated (PWM) signal to adjust optionally the average LED current through duty cycle control.

In addition to the 16-lead TQFN package, the LDS8845 will be made available in a 0.8mm high, 3mm x 3mm 12-lead TDFN by the close of Q2.

The LDS8846 is parametrically identical to the LDS8845, offering a third control input, in pin-compatible 0.8mm high, 3mm x 3mm and 4mm x 4mm 16-lead TQFN packages. The third control input allows the system engineer to configure the LDS8846's LED drivers in one of eight configurations.