Power Adapter Hybrid Integrated Circuit

   The semiconductor circuit of the switching regulator can be divided into a primary circuit and a secondary circuit, which are coupled by a photocoupler. It is unreasonable to design the primary circuit and the secondary circuit on the same integrated substrate to meet the requirements of the insulation withstand voltage, space distance or thickness of the insulator required by the safety specifications. Therefore, the integration degree should be reduced and divided into two pieces.

    In the primary circuit, the oscillation circuit, the pulse width modulation circuit, and the overcurrent and overvoltage protection circuit are common circuits of the small signal system that are not related to the output power of the switching regulator. This part is summarized in an integrated block. According to the output power, the power transistor and its peripheral circuit series are combined by two integrated blocks to form a primary circuit. In this structure, the secondary integrated block is also included, and the three integrated blocks constitute a switching regulator. Although the integration is low, the versatility is high, and it is easy to standardize in the case of a small number of small-scale production.

    When the primary circuit is grouped into an integrated block, the power output range is limited, taking into account the advantages and disadvantages of the high-frequency switching power supply (power adapter), but the integration and packaging cost can be rationalized to reduce the price and achieve miniaturization. It is suitable for mass production models such as home electronics.

    If classified according to the power adapter voltage stability, it can be divided into unsteady power supply, stable power supply, and quasi-stable power supply. The unsteady power supply only rectifies and smoothes the input; the stable power supply detects the output voltage for voltage regulation control, and the quasi-stable power supply is a switching power supply with characteristics between the two.

    The quasi-stable power supply shows a high degree of stability for input variations, but shows a rough stability for load fluctuations. However, as a mechanical system or an acoustic device such as a motor or a relay which does not require such a high degree of stability, and as a pre-regulation, its performance is sufficient. Because of its simple structure, it is very useful, so the circuit design idea of the hybrid IC type switching power supply can be variously combined according to the input voltage range or the number of outputs.