Solution Design: Simple, Configurable LED Driver for MR16 LED Lights

The MR16 lamp is a kind of multi-faceted reflector lamp. It is widely used in commercial retail and home decorative lighting. Because it usually uses halogen filament as the light source, it has many disadvantages such as low efficiency, more heat generation and halogen capsule treatment. . . . But current LED technology offers an MR16-compatible, highly reliable, cost-effective alternative to halogen lamps. For example, ON Semiconductor's CAT4201, which drives three LEDs in series, offers a new option for engineers designing MR16 LEDs. The following will introduce the energy-efficient MR16 LED lamp driver solution that replaces the MR16 halogen lamp in combination with the characteristics of the MR16 lamp.

Halogen and LED characteristics

MR16 halogen lamps are used in creative lighting for many retail and consumer applications due to their unique size, configurability, concentrating power, aesthetics and practicality. Common MR16 halogen lamps have a luminous flux range of 150 lumens (lm) to 800 lm, a luminous efficacy of about 15 lm/W, or a luminous efficiency of 15%. Inefficiencies, heat generation and halogen capsule handling problems are disadvantages of this technique. In addition, typical halogen bulbs have a life of approximately 2,000 hours. It is also possible that the filament is broken due to violent vibrations, causing premature lamp damage.

In comparison, LED has the advantages of energy saving and environmental protection, and the power consumption is quite low. The working voltage of a general LED is 2 to 3.6 V. LED is a kind of cold light-emitting technology, the heat is much lower than ordinary lighting source; LED is completely encapsulated in epoxy resin, there is no loose part in the lamp body, it is not easy to damage, and the service life of LED can be reached under proper current and voltage. 5 to 100,000 hours; LEDs are made of non-toxic materials and are free of contamination. The current shortcoming of LED is that the price is relatively expensive, and the processing of heat is difficult, so the driving power is a key factor in the overall life of the LED lamp.

Replace the low-efficiency MR16 halogen lamp with LED MR16 lamp

ON Semiconductor's CAT4201 is a 300 mA LED driver capable of driving three LEDs in series for MR-16 LED lamp design. The device is optimized for both external component count and thermal performance.

Circuit characteristics

The CAT4201 uses a buck topology that does not require input/output (I/O) galvanic isolation with an input voltage of 12 Vac and an output power of 2.7 W. Other specifications include an output voltage of 9.1 V, a nominal input power of 3.4 W, and a nominal average. The current is 300 mA, the maximum average current is 310 mA, the minimum average current is 295 mA, and the typical energy efficiency is 83%. Figure 1 shows an MR16 lamp circuit using CAT4201.