Luxeon Star LED driver with MAX1709 IC
Posted on Aug 15, 2012 4178
Under: LED Circuits
Anyone who has ever dealt with construction of low-voltage-fed inverter realized that this is no easy task. The shrinking supply voltage decreases rapidly transferred power and efficiency. Samokmitající converters fail to provide sufficient power to drive control for the purpose of unduly complex. Involvement of the drive, greatly simplifies the use of special circuits. For describing the lamp with a colleague, we selected the circuit MAXIM, MAX1709 type, which allows the drive to realize the power, exceeding the needs described lamp.
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Circuit MAX1709 is designed for portable devices for increasing the drive. Depending on the size of input and output voltage is able to supply current to 4 A. The circuit inside the control logic associates, reference source and switching power MOSFET with a channel resistance of closed just 10 milliohms. The circuit just plug coil, diode, filtering and blocking capacitors, one resistor, and the drive is ready. Involvement of the drive for a lamp is on Figure 1 . Inverter circuit is off-state power from the battery through the diode D1 and R1 to the OUT pin (9). After switching circuit is controlled by an auxiliary oscillator. Only increases when the supply voltage of 2.15 V, the circuit goes into normal mode. Output voltage is controlled by a feedback loop. The voltage from resistive divider is compared with a reference voltage of 1.24 V and the voltage deviation under the control of the power transistor switching time. The output voltage can be adjusted in two ways. If the FB input (10) is grounded, the internal divider circuit. It is fixed to the output voltage of 3.3 or 5 V by the level of the 14th pin Any output voltage can be set between 2.5 to 5.5V by an external divider. The converter described here is fixed 3.3V output voltage Drive is not appropriate to turn a normal power supply connection. Power consumption is already so large that we had used a robust switch. However, any contact resistance significantly...