First, DC-DC chip increases synchronous rectification, reducing power supply volume and weight:
Synchronous rectification is a new technology that uses a very low on-resistance power MOSFET to replace the rectifier diode to reduce rectification losses. The turn-on loss of the MOS transistor is greatly reduced. The power MOSFET of the same power generally uses the PCB to dissipate heat, and the diode rectification requires the use of a heat sink.
The following describes a relatively simple Buck circuit using the synchronous rectifier chip technology DC-DC chip MP4420.
The MP4420 integrates the two MOSFETs Q1 and Q2 in Figure 3 and is packaged in a SOT23-8. The DC-DC conversion function can be realized by adding an inductor and a capacitor to the periphery of the chip, thereby saving the product volume.
Second, the AC-DC power supply uses the primary side feedback to save some devices:
The primary side feedback (PSR) AC-DC control technology is a new AC-DC control technology developed in the last 10 years. Compared with the traditional secondary feedback optocoupler plus TL431 structure, its biggest advantage is that it is omitted. These two chips and a set of components that work with them save space on the system board and reduce circuit cost while ensuring reliability.
MPS currently has a series of 5~15W primary feedback control chip solutions. MP020 is a constant voltage constant current (CV/CC) switch chip with integrated 700V MOSFET, which can easily achieve high precision voltage regulation and constant current output.
Third, miniaturized power module applications, reducing product size:
The power module can be directly mounted on the printed circuit board, and the module product has advantages in terms of volume, heat dissipation and reliability due to the design of the glue module. AC-DC power supplies often need to meet some safety distances, resulting in a large circuit area of the AC-DC. The AC-DC power supply module can greatly reduce the distance between components and wiring because of the potting package, which can greatly improve the power supply. Power density.