Car cigarette lighter circuit diagram output DC voltage is 12 V, even when the engine is running will not exceed 13 .8 V, 19 V voltage lower than the normally required of notebook computers. The boost converter voltage conversion, the basic circuit shown in Figure 1, which consists of power switch T, diode D, the energy storage inductor L, and filter capacitor C The inductance constantly charge and discharge, the induced voltage is added to the resulting output voltage on the power supply voltage higher than the voltage provided by the car cigarette lighter.
(1) S conduction, D, cut-off: the input DC power UIN IIN current pathway formed by the inductance coil L and switch S DC power charging the inductor, the inductance L of the current linear increase in electrical energy to magnetic energy stored in the coil. At this point, the diode D is reverse biased, and output loads current IOUT from the energy stored in the capacitor C, as shown in Figure 2 (a) below.
(2) S off: D conduction due to the inductance L of the current can not jump, induced in the coil shown by a very sexy raw voltage. Therefore, the polarity of the induced voltage is left negative right being. The diode D into a forward state, the original through the diode D in S during the conduction of the energy stored in the inductor coil to the capacitor C and load RL. C at this stage, the energy charge in the next S period ending provided to the load RL.
The boost converter in the power switch S, one in the state of switch power MOSFET tube. Gate with a series of pulse power tube in the state and off alternately, changing the ratio of off time, you can adjust the size of the output voltage. Suppose that a cycle t, t = tON when the positive pulse, pulse width modulation pulse was sent to the gate of power transistor K conduction; when t = M1 is turned OFF (tOFF), modulation pulse sent to the K tube into the zero volt or negative bias, S in a closed state.