LED driver solution for various medium voltage general lighting applications

Many medium voltage LED applications are powered by off-line AC-DC power supplies, batteries or electronic transformers with low voltage AC outputs. But some of these power supplies, such as lead-acid batteries, have only undergone simple regulation. Therefore, there is a need for an LED driver solution that can operate over a wide input voltage range and can be configured in a variety of topologies to support LED load requirements. Depending on the current and operating conditions of the LED, a linear or switching regulator LED driver solution can be used. ON Semiconductor offers a wide range of topologies for medium voltage LED applications for landscape lighting, low voltage track lights, solar powered lighting, automotive lighting, emergency vehicle lighting, marine lighting, 12 Vac/Vdc MR16 lights, aircraft interiors Various general lighting needs such as lighting, sign backlighting, billboard text circuits and signs.

Figure 1: Example of LED landscape lighting

Medium voltage LED general topology and power supply

Medium voltage LED lighting applications require an optimized driver solution. ON Semiconductor offers medium voltage LED driver solutions in three different topologies, including inductive, charge pump and linear, to meet different application needs. See Figure 1.

Figure 2: Example of three topologies

There are several power supplies for medium voltage LED applications, each with its main purpose. Among them, off-line AC voltage regulator adapters, common voltages of 12, 24, 36, 48 Vdc, voltage regulation accuracy of ± 5%, suitable for low to medium power applications with low safety requirements. Sealed lead-acid batteries, which are only widely regulated, 8 to 14 Vdc, are widely used in automotive lighting; 7-27 Vdc are used in automotive, solar, and marine lighting. 12 Vdc and 12 Vac power supplies, common in indoor lighting, track lights, outdoor lighting, landscape lighting, etc.

ON Semiconductor Medium Voltage LED General Lighting Solution

1) Linear LED driver solution

Linear solutions are the preferred method for many lighting applications because they are designed to be simple and intuitive, and allow LEDs to be driven with precision currents, regardless of how the LED forward voltage or input power is changing.

Because such LED drivers are linear, they must match the power requirements of the application. ON Semiconductor offers a wide range of constant current linear LED drivers with currents from 10 mA up to 1 A. The channel output current is 10 to 50 mA with NSI50010Y, NSI45020JZ, NSI45020, NSI45020A, NSI45025, NSI45025A, NSI45025AZ, NSI45025Z, NSI45030, NSI45030A, NSI45030AZ, NSI45030Z, NSIC2020B, NSIC2030B, NSIC2050B and NCV7680; 60 to 350 mA with NSI45060JD, NUD4011, NSI45090JD and CAT4104; NUD4001 (500 mA) and CAT4101 (1000 mA) with larger channel output current.

Figure 3: NSI45 application circuit

Take the linear constant current regulator NSI45 series as an example. This is a two-terminal or three-terminal linear constant current regulator. Based on ON Semiconductor's patent-pending self-bias transistor technology, it is ideal for a wide range of LED applications with different input voltages. Such as driving currents in building, automotive and industrial signage LED lighting applications. It operates over a wide input voltage range, giving engineers a simple, cost-effective, current-stable solution for their application without sacrificing performance. The constant current regulator series stabilizes over a wide range, ensures constant brightness over the operating voltage range, and has a negative temperature coefficient characteristic that protects the LED from thermal runaway at extreme voltages and operating temperatures. .

Another typical application of the NSI45 is a constant current regulator linear LED driver used as a display and billboard text circuit. Features include a low starting voltage, precise current regulation regardless of the forward voltage (Vf), and a negative temperature coefficient to protect the LED.

Figure 4: NSI45 display and billboard text circuit application examples

2) LED MR16 bulb solution

The NCL30100 is a step-down LED driver controller with energy-efficient, peak current control adaptive fixed off-time for low-power and space-constrained applications where space and energy efficiency are critical. The solution has an oscillating frequency adjustable characteristic. The continuous conduction mode (CCM) can eliminate the output capacitance, the energy efficiency is up to 95%, and provide natural LED open circuit protection.

The driver controller has a switching frequency of up to 700kHz and does not require an output capacitor. The Vcc operates from 6.35 to 18 V and can drive one or more high-power LEDs, mainly used in MR16 LED lighting, ambient lighting, solar LEDs, traffic lighting, Applications such as outdoor lighting and LED strips. The PCB with the NCL30100 is very compact and fits into the lamp holder of the MR16 lamp. The hysteresis control feature of the NCL30160 provides fast response during load transients, eliminating the need for small signal control loop compensation components. Protection features include the ability to set LED current, LED short-circuit protection, undervoltage lockout, and thermal shutdown.

The NCL30100 utilizes negative current sensing to reduce power loss with small inductors for low cost, energy efficient, and low component count applications. The device features a low-side N-FET switching topology and continuous conduction mode operation without the need for an output capacitor. Therefore, the evaluation boards NCL30100ADLMGEVB and NCL30100ASLDGEVB from ON Semiconductor can be used to place the circuit into the MR16 lamp holder, which also enables PWM dimming.

Figure 5: NCL30100 LED Driver Controller Circuit

Figure 6: NCL30100 Evaluation Board

In addition, for the 12 V AC-DC design of 3 to 4 LED modules, the evaluation board NCP3065BBGEVB supplied by ON Semiconductor for the NCP3065 can be used. It can be used to drive Sharp ZENIGATA®, Cree XLampTM MC-E and other LED modules in 12 Vac/Vdc applications. Since the module forward voltage overlaps the input voltage range, only one switching buck-boost configuration is used. Its characteristics are small size, wide input and output operating voltage, output current through steady current, LED open circuit protection, output short circuit protection. The solution is suitable for MR16 bulbs, landscape lighting, traffic lighting, and more.

Figure 7: LED and Reference Design Demo Board for Buck-Boost MR16 Lamps

3) Solar powered LED street sign solution

The NCL30160 is a switching regulator for high-power LEDs that uses a constant voltage provided by a NCL30051-based power supply to reduce the voltage to provide a constant current to the LED string. By utilizing a low on-resistance internal MOSFET of only 30 mΩ and the ability to operate at 100% duty cycle, a solution with up to 98% efficiency can be provided.

Operating from an input voltage range of 6.3V to 40V and switching frequencies up to 1.4 MHz, the device is an excellent solution for industrial and automotive applications. The high switching frequency allows designers to use smaller external components to help minimize board size and minimize cost. The NCL30160 includes hysteresis control to provide fast response during load transients, eliminating the need for small signal control loop compensation components. Protection features include the ability to set LED current, LED short-circuit protection, undervoltage lockout, and thermal shutdown. There is also a dedicated PWM dimming pin/low power shutdown feature.

The NCL30051 works in conjunction with the NCP30160IC to simplify power supply circuit design with minimal external components. This architecture enables the chipset to be integrated into more compact and cost-effective LED lighting power supplies for general lighting applications such as outdoor lighting (such as LED street signs, street lights, and parking lots).

Figure 8: Solar-powered LED street signs and drive solutions

Push LEDs to replace incandescent lamps

According to the "Notice on the gradual ban on the import and sale of ordinary lighting incandescent lamps" jointly issued by the National Development and Reform Commission and other departments, from October 1, 2012, the import and sale of ordinary lighting incandescent lamps will be phased out in accordance with the power level. Using core strengths and strengths in power management, energy-efficient power supplies and packaging, ON Semiconductor has developed dedicated LED drivers for different applications, as well as solid-state lighting solutions that meet or exceed regulatory requirements around the world, providing a revolution in lighting. Rich choices will play an active role in this process.