how to choose a led driver
LED has undoubtedly gained a strong foothold in the backlighting of an assortment of devices due to a variety of reasons which include energy-efficiency, environmental friendliness, robustness, and the low cost of maintenance. However, an integral part that allows room for all this to happen is the driver circuit regardless of whether it is for general lighting, backlighting or for use inside the constructs of a display panel. What is important is the choice of architecture from a technical perspective of the driver circuit that must be able to correspond to the requirements of specific applications.
LED Tech Leaps Forward with LED Driver ICs
The LED industry’s technological scope has progressed in conjunction with the digital and electronics industry which allowed advancements within the spectrum of LED technology to develop the circuitry or LED driver. This development provided a critical jump to the LED display industry to take a significant leap ahead of other types of display technology. In essence, the LED driver is an electrical circuit that is required to channel power into an LED (light-emitting diode) unit. The circuit acts as a gauge that transmits or supplies power (either DC or AC) in order to start up the LED unit at a certain level of brightness. However, the current that is supplied has a limitation or rather an upper-tier or limit that prevents the LED from getting damaged. There are two primary types of LED drivers which are ‘direct drive’ and ‘multiplex display’ techniques which are briefly explained below.
Direct drive
Direct drive revolves around the use of a multitude of independent single LED circuits (single string). A simple example of this type of LED driver could be seen in a digital clock with a 7-segment display and when the clock displays 13:00 it only turns on the necessary segments and leave them turned on up to the moment when another segment is required to be displayed.
Multiplex display modes
Multiplex display modes which are more commonly used compared to direct drive ICN simply because they are cost-effective. Taking the same clock example from the direct drive the design of the ‘7 segment’ digital clock displaying 13:00 at any given time, the clock turns on the appropriate segments of just one digit maintaining all the other remaining digits as ‘off’ or dark. In essence, the clock is scanning the digits very rapidly which is enough to present the illusion that the clock is constantly displaying “13:00” for the whole minute when it is actually pulsating on and off several times within a single second.
Multiplex display modes
ICs are basically an abbreviation for ‘Integrated circuits’ and in essence, are the keystones of modern-day electronics. In other words, they are the heart and brains of any given circuit, including the circuitry that runs LED display units. If you are still fazed about what ICs are, they are the little black “chips” that we see ‘fitted’ on electronic-boards that are inside electrical products with control systems. These ‘chips’ are not a single element and consist of a multitude of components such as resistors, capacitors and transistors among others fitted together into tiny little chips. When electronic wizards such as those at Street Communication which is a leading LED display solution provider based in France connect these ICs together, they create magic with their LED display capabilities.
This article will mainly examine 2 specific MBI (Macro Block) LED drivers that are generally used for LED video displays which are the MBI 5153 and MBI 5124. Both display driver ICs have both unique and common characteristics which are critical their respective functions for LED video display units.
Brief on MBI 5153 Display Driver IC
The construct of the MBI5153 display driver ICN is designed for the objective purpose for use in LED video applications. The display driver IC uses an internal PWM (Pulse Width Modulation) control system that is coupled with a selectable 14 bit/13-bit colour depth. The IC is also unique because it is able to convert serial inputs into each pixel’s grey scale’s output. Another distinct feature of the MBI5153 is the 16-bit shift register which allows its current ports to deliver uniform current sinks that are constant for driving the LEDs that come with a wide selection of VF variations. Output current flow is capable of being pre-set via external resistors. The innovative architecture of the MBI 5153 ICN Display Driver IC according to the technicians at Street Communication are fitted with SRAM that is capable of supporting 1:32 time-multiplexing applications.
This means that the user is only required to send entire data frames once which are stored in the embedded SRAM, eliminating the need to send each time the scan line changes. This feature effectively saves data bandwidth whilst simultaneously achieving high grey-scale at low data clock rates. Using Scrambled-PWM technology, this particular LED display driver IC enhances PWM which enhances visual refresh rates of scan-type LED displays. Apart from the compulsory error detection function of this display driver IC, enables it to identify singular LED for open-circuit errors without the need for extra components.
Brief on MBI 5124 Display Driver IC
The MBI 5124 Display Driver ICN is fitted with a 16-Channel Constant Current LED Sink Driver that is coupled with Precision Drive™ technology. The MBI5124 is uniquely constructed for LED displays that are required to function with low levels of current and simultaneously match up with the luminous intensity for the singular channels. This display driver IC is also distinct in its own way because it is not only able to supply of voltage but also accepts CMOS logic inputs at 3.3V and as well as 5.0V for the sole purpose of meeting the current trend of low levels of power consumption. The IC also equipped with a dedicated serial buffer and data latches that are also able to convert serial input data to output formats that are parallel. Similar to the MBI 5153, the output stage of MBI 5124 has 16 regulated current ports that can provide constant and uniform current sinks for driving the LEDs with multiple VF variations.