New Industry Products

Maxim Offers New HB LED Driver For LCD TVs, Monitors, & Automotive Displays

September 09, 2009 by Jeff Shepard

Maxim Integrated Products introduced the MAX16814, a highly integrated four-string HB (high-brightness) LED driver capable of delivering up to 150mA per string. This device is said to pack in all the features necessary to implement a high-performance backlight driver for LCD TVs, monitors, and automotive displays. Through this integration, the MAX16814 is said to give designers a cost-effective solution that greatly simplifies their lighting designs while offering unmatched performance.

The MAX16814 integrates a switching dc-dc controller to generate the voltage required to drive multiple strings of LEDs. It also features four linear current sinks with internal power MOSFETs to provide programmable current up to 150mA per string. An adaptive output-voltage control scheme optimizes efficiency and minimizes power dissipation in the LED current-sink paths. This architecture eliminates the need for multiple external components, thus saving space and easing design in space-constrained applications.

The MAX16814 is well suited for backlighting LCD TVs, desktop monitors, automotive displays and instrument clusters, and industrial displays. It is also well suited for automotive front lights and low-/high-beam assemblies, as well as other SSL (solid-state lighting) applications.

According to Maxim, HB LEDs are rapidly replacing CCFLs as the backlighting technology of choice in LCD TVs, desktop monitors, and automotive displays. The main drivers for this conversion are the lower energy consumption, smaller form factor, and higher reliability of HB LEDs compared to CCFLs; additionally, HB LEDs do not contain hazardous chemicals such as mercury. Most of these applications use multiple LED strings and, of course, need to keep cost as low as possible. Multistring drivers present an excellent solution to these requirements, as they reduce cost and improve integration at the same time. However, their use presents a number of design challenges related to efficiency, power dissipation, dimmability, fault protection, and EMI (electromagnetic interference).

The MAX16814 features open and short fault protection. In the event that an LED shorts or becomes an open circuit, the driver detects the fault and automatically turns off the affected string, while keeping all other strings active. This protection scheme minimizes the effect of the failure and prevents further damage to the system. In both cases, an output pin signals the fault condition to the rest of the system.

Additionally, the MAX16814 features thermal protection to prevent damage to the circuit from over-temperature conditions. Combined with the device’s high input-voltage capability and wide operating-temperature range, these fault protections virtually guarantee reliable operation in harsh electrical and thermal conditions.

The MAX16814 is fully specified over the -40 to +125°C automotive temperature range, and its wide input-voltage range (4.75 to 40V) allows it to withstand 40V load dumps. The device is available in thermally enhanced, 4 x 4mm, 32-pin TQFN and 20-pin TSSOP packages. Prices start at $1.39 (1000-up, FOB USA).