3 Companies Capitalize on Dimming and Simplicity with New LED Drivers
Recent LED drivers from Maxim Integrated, STMicroelectronics, and ON Semiconductor promise improved performance in LED lighting applications. This article covers these releases and their specifications.
From lighting your house, your car's headlights, and the lights in a shopping market, lighting can always be something taken for granted until you no longer have it. This can also apply to the various components working to fix problems as difficult as board simplification to as seemingly simple as brightness. One component that recently showed a rush of releases is LED drivers.
An example of a general nonsynchronous buck LED driver diagram. Image used courtesy of Maxim Integrated
Recently, LED driver releases from leading electronic component manufacturers Maxim Integrated, STMicroelectronics, and ON Semiconductor promise greater performance in various electronic applications. These products offer advanced functionalities and application-sensitive dimming capabilities, a potential industry standard in future driver releases.
This article aims to explore these recent releases, their similarities, and key applications in LED lighting.
Uninterrupted Brightness with Maxim's Integrated LED Driver
The MAX25512, a new LED backlight driver from Maxim Integrated, promises uninterrupted brightness for in-car displays. This recent announcement noted its simple design amidst its advanced capabilities, as well as some of its key advantages:
- High component integration
- Low cold crank and start-stop voltage
- Small size
- High component integration
This driver integrates a boost converter and current sense resistor. Although it removes the external MOSFET that supports automotive displays, it further integrates an I2C communication interface to display diagnostics and settings and a hybrid dimming function to limit electromagnetic interference.
The exclusion of the external MOSFET and high integration of its components makes the MAX25512 a small-sized LED backlight solution.
Block diagram for MAX25512. Image used courtesy of Maxim Integrated
Another key feature of this driver is how it retains thorough, round-the-clock in-car display brightness during extreme start-stop and cold crank conditions.
This feature is achieved because of its low input voltage (3 V) and its ability to operate efficiently at a switching frequency ranging from 400 kHz to 2.2 MHz. The driver also ensures a safer and higher-quality display by featuring advanced diagnostic functions. One such function is short to ground, which is on its current sinks with state-of-the-art alert capabilities
The ability of such a design to withstand cold crank conditions allows for a wide range of applications. Its availability in a compact TQFN package claims to reduce board space up to 30%, in addition to lowering the bill of material (BOM) costs. Additionally, it circumvents the need for a pre-boost converter while protecting the displays from power disruptions.
Though Maxim created an innovative way to free up board space, the next LED driver attempts to provide constant brightness.
STMicroelectronics’ LED Driver Targets Constant Brightness
The ALED6000 LED driver, recently released by STMicroelectronics is suitable for both interior and exterior LED lighting. The design is a mix of high component integration and flexibility. Being a single-chip automotive LED driver with an integrated DC-DC converter provides consistent brightness regardless of the vehicle's electrical conditions.
This driver can also drive a single string of LEDs in automotive stoplights, headlights, turn signals, rear lights, daytime running lights, and interior lights. It has an extensive input voltage range from 4.5 to 61 V. STMicroelectronics also claims to have equipped it with a dedicated pin to apply pulse width modulation (PWM) control signals and advanced digital dimming capabilities.
An application schematic for the ALED6000. Image used courtesy of STMicroelectronics
The design flexibility that the LED driver offers could be beneficial in powering LED strings with voltage requirements above or below its input voltage. It also claims to efficiently handle voltage supply fluctuations. Other specifications of this LED driver include:
- Its adherence to the AEC-Q100 standards
- A DC output current of up to 3 A
- Switching frequency range of 250 kHz to 1.5 MHz
- Low quiescent current: 2.4mA during operation, and 11µA at shutdown
- A ~3.2% accuracy level of its output current
- The ability to adjust its current limitation
This LED driver's flexibility could provide useful depending on the design; however, what if your design is RF-sensitive?
ON Semiconductor Targets RF-sensitive Applications
Following the wakes of the last two releases, two new LED drivers have also recently been released by ON Semiconductor, namely the NCL31000 and NCL31001. Both drivers aim to be suitable for lighting up airports, warehouses, supermarkets, hospitals, and more. These new releases could add accurate positioning and data intelligence to lighting solutions, and OEMs can also now incorporate visible light communication and light-based positioning technologies into their LED lighting designs.
A block diagram of NCL31000. Image courtesy of ON Semiconductor
A few specifications of ON Semiconductor’s new LED drivers include:
- Switching frequency ranges from 44.4kHz to 1MHz
- A 21.5V to 57V input voltage range
- Linear dimming to zero current with 0.1% accuracy
- A 48-pin, 7-by-7 QFN package
- Simple design and high efficiency
- I2C/SPI interface
- −40°C to 125°C junction temperature
- Accurate current/voltage measurements with diagnostic functions
Typically, RF-based LED solutions can be inappropriate in many RF-sensitive applications (such as those related to lighting mines, aerospace, and hospitals). Despite this, the NCL31000 and NCL31001 LED drivers could be beneficial because they claim to ensure accurate linear dimming as an alternative to RF-based solutions.
Being able to dim down to zero current can help eliminate ghost light in the lowest dim settings. These drivers simplify designs and boost efficiency by incorporating a 3V3 fixed DC-DC converter and a DC-DC (2.5 to 24 V) that is adjustable.
After covering these three new LED driver solutions, let's see how they stack up to one another.
Similarities Between Maxim, STMicro, and ON Semi’s New LED Drivers
As all three of the above companies released a new LED driver recently, the below list covers some similarities between what each manufacturer claims to have achieved:
- A low bill of materials
- Constant brightness
- Accurate dimming capabilities
- Efficient power fluctuation handling
- The application of the I2C communication interface
- High component integration
The manufacturers’ LED drivers do, however, differ in the following areas, from field application to temperature.
While the MAX25512 is appropriate for in-car displays, the ALED6000 is well suited for interior and exterior automotive LED lighting solutions. The NCL31000 and NCL31001, on the other hand, were designed for non-automotive applications altogether: supermarkets, warehouses, hospitals, airport lighting, and more.
When it comes to input voltage ranges, Maxim, STMicro, and ON Semi’s products all have different input voltage ranges, respectively: 3 V for the MAX25512, 4.5 to 61 V for the ALED6000, and 21.5 to 57 V for the two ON Semiconductor LED drivers.
As for switching frequency, each of the three manufacturer’s LED drivers possesses varying switching frequencies: notably, the MAX25512 has the highest at 400 kHz to 2.2 MHz.
Finally, as for operating temperature, Maxim’s MAX25512 and STMicro’s NCL31000 and NCL31001 devices share an operating temperature range of −40°C to 125°C; however, the ALED6000 is notably higher at −40°C to 150°C.
By looking at these stark differences, it is important to consider the design requirements. OEMs, EEs, and other designers must consider factors such as the above areas, particularly regarding the differences that occur from one device to another. For instance, when a manufacturer attempts to select the most efficient LED solution for their design goals, one LED driver may have a unique feature that will prove valuable: for example, ON Semi’s advanced diagnostic capabilities.
LED Driver Trends
Intuitive designs and dimming features are the new trends in the latest LED drivers. Companies such as Maxim Integrated, STMicroelectronics, and ON Semiconductor have promoted simplicity by eliminating the need for an external MOSFET and high component integration while boosting their technological capabilities. Plus, all four LED drivers claim to incorporate advanced dimming functionalities that offer several benefits in a wide range of applications. And, in the near future, these trends could even become a type of standard in the industry.