led power 50w is very common, especially in some high-end portable light flashlight used widely. This type of flashlight commonly used single-cell alkaline batteries or nickel-metal hydride rechargeable battery-powered, so the volume is very small.
led 10w work process may have a fever temperature rise, the current flowing through increasing with increasing temperature, large currents will seriously affect the LED luminous efficiency and lifetime. Therefore, the power LED constant voltage power supply. Constant current drive. Example, in a led 1w , and general requirements for a 350mA constant current to power. If you want to DIY a high-power LED flashlight, making a constant current source became the focus.
The constant current source is divided into two kinds of linear constant current source and switching constant current source. Linear constant current source circuit is relatively simple, easy to produce, but its low efficiency, is not suitable for use in battery-powered systems. Another point is the linear constant current source can not be achieved step-up when the load voltage is higher than the supply voltage (for example, a single alkaline cell drive power LEDs), this approach can not be used. The switching constant current source just to make up for the shortcomings of the linear constant current source with high efficiency to achieve the advantages of boost and buck. The only downside is the circuit is relatively complex.
Here are the pieces of a single High Power LED 50W chips - Linear Technology's LT3490. I trial, the effect is very good, very suitable for DIY flashlight.
The LT3490 is a fixed oscillation frequency (1.3MHz) efficiency boost led power 10w , input voltage range of 1V ~ 3.2V, the output constant current 350mA. Figure 1 shows the typical application circuit of the LT3490. The battery for single-cell or two Ni-MH battery or a single alkaline battery, the circuit output constant: 350mA current. The figure only four external components, the circuit board can be used to the heat transfer of production into a disc shape. Of particular note is the choice of the inductor L1, the LT3490 internal switching frequency more than 1MHz. In order to reduce the core losses, the winding of L1 should be used high-frequency core; L1 equivalent series resistance (ESR) as small as possible in order to reduce the heat loss of the coil. In addition, the saturation current of L1 is greater than the peak current in the coil, requires L1 saturation current at 1A above.