At present, in the area of high-brightness LED street lighting drivers, there are two major solutions that widely used in the world: “special power chip” and “switching power supply with discrete electrical components”. In order to meet the needs of intelligentization, single chip microcomputers (SCM) are usually embedded into devices as the CPU. Thus both of these two solutions can be classified as “system supervisory + power controlled traditional multi-chip technology program”. However, this sort of sophisticated solution has a lot of disadvantages: multiple chips and complex constructions. When using on LED street lighting products that need to drive multiple LED strings with high brightness, this shortcoming is particularly prominent.
The new Piccolo TMS320F2802x/3x MCU adapted the latest architecture technology and enhanced peripherals. The minimum package size is 38 pins, providing 32-bit real-time control functions for low cost LED street lighting products. The real-time control are usually embedded with intelligent devices, like solar micro-inverters, LED lighting applications light solution , large household appliances, hybrid board battery industry, automotive applications, etc. to realize the implementation of advanced algorithms, higher system efficiency and accuracy.
The Buck-type switching power supply is one of the most widely used power solutions. This type of power supply can make the entire system work in the continuous inductor current mode by choosing correct output inductor and switching frequency. LED lighting Demo based on TMS320F28027 fully adapted working principles of Buck-type switching power supplies, combined with multi-PWM channels (8 channels tops) and ADC modules (16 channels tops) to realize the closed-loop control of current.
This single-chip solution for high-brightness LED street lighting products combined system management and power supply control, dramatically reducing the complexity of hardware constructions and meanwhile improving the flexibility of driver circuit designs. LED street lighting products applied this solution can automatically control multiple parameters, like current amplitude, on-off period, on-off mode, ambient brightness and system temperature by changing the memory of CPUs. They have basic properties as below:
1) Low cost – single-chip realize multiple constant current control, eliminating the need for a dedicated constant current chip, which effectively reduces the production cost.
2) High efficiency – non-insolated power supplies, without any magnetic flux leakage loss causing by transformers. The overall efficiency can reach up to 95% at fully loaded.
3) Strong driving ability – 8-channel non-isolated current driver output can drive 8 strings (not less than 14 chips per string). The total output power is not less than 100W.