Oct 24, 2016: LED drivers are referred to as electrical devices that regulate power to an LED or a series of LEDs. They help to prevent damage to LEDs as the forward voltage (VF) of a high-power LED changes with temperature.
The LED driver is a self-sufficient power supply which has outputs that are coordinated to the electrical characteristics of the LED. This helps prevent thermal runaway as the constant current LED driver compensates for the transitions in the forward voltage whilst delivering a constant current to the LED.
The development of LED technology has created an extensive range of LED driver IC options in the semiconductor market. A suitable driver creates a thriving application. Some of the major developments in LED applications are TV backlighting, automotive lighting, smartphone backlighting, dimming LED lamps and LED signage.
In today’s time, LEDs are being used for backlight technology in varying sizes of laptops, TVs, monitors and so on. The backlight unit (BLU) in a TV is a chief source of power consumption.This is where LED drivers come into the forefront as they offer power reduction through a number of backlight architectures, in both edge and direct backlight.
LED drivers in automotive lighting help to save energy while providing visibility solutions. LEDs help to improve the safety of drivers by improving visibility range when the headlights are or dimmed or turned on/off, to efficiently perform at any phase of the drive.
There are several approaches for controlling LED lighting, and LED drivers not only offer efficiency but also reliability by selecting the suitable parameters. Advancement of technology will give rise to better LED driver applications capable of reducing power consumption without trading-off with respect to efficiency, component counts and switching frequency.
Have a look at the five emerging LED driver products.
NXP Semiconductor’s MC34844 for TV backlighting
NXP Semiconductor’s MC34844 is a popular LED driver for backlighting small- and medium-size LCD panels. It particularly serves high-definition and low-power portable devices such as small-screen TV’s, personal computer notebooks, monitors, etc.
This LED driver operatesfrom supplies of 7 to 28 V, and has the ability to drive up to 160 LEDs in 10 parallel strings. It also features LED open-circuit protection, LED over temperature protection and LED short protection. On the other hand, the IC features overcurrent protection, undervoltage lockout and overvoltage protection.
Cypress’s S6BL112A automotive LED driver
The S6BL112A by Cypress is a single-output synchronous buck LED driver, which supports PWM dimming as well as analogfunctions. It features a frequency adjust pin that permits a user to adjust the frequency from 205 kHz to 2.1 MHz.
Having an input voltage range of 4.5-42 V, this automotive LED driver can handle severe operating conditions like cold-cranking. The LED driver can function during load dump, a power surge that takes place when an automobile battery is disconnected while the alternator is supplying power during engine operation.
LYTSwitch-7 for dimming LED lights
The LYTSwitch-7 by Power Integrations is a buck LED driver IC, which features a buck topology with a power factor higher than 0.9. This LED driver is compatible with TRIAC dimmers, and can deliver up to 22 watts. Its 735V integrated MOSFET ensures adequate overvoltage protection during line surge incidents.
The LYTSwitch-7 design helps to provide a wide input (90 VAC – 308 VAC) and output voltage range operation.Bleeders are not included in its design. Hence, single winding inductor and passive damping and are used for TRIAC supervision.
Maxim’s MAX7219 for LED signage
Maxim has come up with MAXREFDES99# , which is a reference design that adds four of its MAX7219 LED drivers to create a 16 × 16 display with 256 LEDs. The reference design can be powered from a wall-wart which gives a minimum of 7W of power and an output voltage in the range of 7.5 V dc to 12 V dc. It works well with both ARM mbed as well as Arduino platforms.
The MAX7219 LED driver is a compact, serial input/output common-cathode display driver that interfaces microprocessors (µPs) to seven-segment numeric LED displays of up to eight digits, bar-graph displays, or 64 individual LEDs.
AMS’ AS3492 for smartphone lighting
AS3492 LED driver by AMS is an inductive DC-DC converter capable of driving up to five strings with two LEDs each in sequence with 86% system efficiency. It works at a fixed frequency of 2 MHz and features a soft startup that facilitates easy integration into noise-sensitive RF systems.This LED driver has been particularly crafted for mobile phones,PND and PMPs and digital cameras.
The AS3496 has a number of built-in protection mechanisms such as Over Voltage Protection (OVP), Open LED Protection (OLP) and Short LED protection (SLP).