hid electronic ballast circuit diagram

( HID ) or high pressure sodium lamp electronic ballast designed with PM4020H :

Using a large current push-pull circuit, it can drive half-bridge and full-bridge circuits. The bridge output uses low-frequency AC, and the PM4020H's built-in crossover reduces the frequency of the single-ended driver to a low frequency of 195Hz, thus eliminating acoustic resonance.

PM4020H controller

HPM4020H integrates all the functional requirements for controlling and driving H IDL . It is suitable for driving and controlling high-intensity discharge lamp controllers such as metal halide lamps (such as car headlights, projector lamps, etc.), high-pressure mercury lamps and high-pressure sodium lamps. It contains a complete current mode pulse width modulator, a lamp power regulator, lamp temperature compensator and all fault protections.

The structure and functions of HPM4020H are shown in Figure 1. Using a large current push-pull circuit, it can drive half-bridge and full-bridge circuits. The bridge output uses low-frequency AC, and the PM4020H's built-in crossover reduces the frequency of the single-ended driver to a low frequency of 195Hz, thus eliminating acoustic resonance. Acoustic resonance is a phenomenon in which the discharge arc is unstable when H IDL is powered by a high-frequency power supply. The mechanism is that the pulsation of the pressure wave in the lamp is reflected back from the inner wall of the tube. If it is in the same phase as the pulsating component of the high-frequency current, a stationary wave will form. Waves produce acoustic resonance, which can cause the light to shake in the least case, or burn out the lamp tube and ballast in the worst case.

The output of the controller uses a full-bridge inverter. The inverter operates at a low frequency of 195Hz , and the average voltage of the lamp is zero. The driver of the bridge is output by pins QOUT and QOUT. They both work at a 50% duty cycle, with a difference of 180°. IR2112 is used to drive the high-end and low-end MOSFET tubes . This method is more expensive, and can also be driven directly at the low end. The high end uses a high voltage transistor, a pull-up resistor and the correct phase. Below is the detailed circuit diagram . figure 2: