Date: 20/02/2011

Multi channel LED driver ICs for LCD TVs and displays

Semiconductor Company of Panasonic Corporation has developed a four-channel LED driver IC (model number: AN37010) that can drive multiple LEDs connected in series for edge-type LED backlight LCD TVs, based on the 190V voltage processing technology. Samples will be available in March 2011 at a cost of 200 yen (approx. 2.40US$) each.

A single chip of the AN37010 LED driver LSI can drive up to 228 LEDs (for 42-inch TV) in four light bars, each of which consisting of 57 LEDs, in a backlight of an LCD display and also incorporates four current sources with a 190V voltage, a boost converter, and various protection circuits. This technology contributes to the down-sizing and cost-reduction of LED backlight modules. Furthermore, this LSI supports ON-OFF control, which the LED backlight in LCD TVs uses to improve the picture quality and reduce power consumption.

Conventional LSIs drive multiple serially connected LEDs by providing each channel with external MOSFETs that protect the LSI from high voltages. However, this has been one of the factors of increased system cost of edge-type LED backlight, which is expected to be the mainstream in the near future. Driving multiple LEDs in series by a single LSI free from the external MOSFETs has been eagerly awaited, says Panasonic.

LED-dimming-control technologies supporting PWM (pulse-width modulation) pulse input-based LED current duty-cycle control and external voltage application-derived current value control

The other key features are:
Reduction of four external MOSFETs for protection against high voltages
This chip integrates peripheral circuits (a boost converter and protective circuits, such as LED short-circuiting detection circuits) and also reduce the mounting board area by approximately 40%.
Enables the LED backlight-specific area-divided ON-OFF control to reduce power consumption and improve the picture quality of LCD TVs.

Texas Instruments has also introduced a serial-controlled, 16-channel constant-current sink LED driver with four-channel grouped delay. This device simplifies design in LED display applications, including video displays, message boards, amusement illumination and LED indicators.

The key features of this device include:

The TLC59282 minimizes simultaneous switching noise by staggering the switching of the LED outputs, lowering the peak switching current transients facilitating low-cost, two-layer printed circuit board (PCB) routing in LED modules.
TLC59282 delivers same precision and accuracy across all channels to ensure uniform current is supplied to each LED string by delivering Channel-to-channel current accuracy: +/-0.6 percent, typical, and chip-to-chip current accuracy: +/-1 percent, typical.
3.0-V to 5.5-V input voltage range.
LED channel voltage up to 17 V.
Four-channel group delay minimizes simultaneous switching noise.
Cascadable serial communication protocol allows a display processor to control multiple LED drivers on the same serial bus. Precision current matching aids uniform LED brightness between strings.
30-nanoseconds blank pulse allows for high refresh rates in multiplexed applications.

Availability: Now
Price: Each $0.47 in quantities of 1,000