Power/Ground Handling
Even if the wiring in the entire PCB board is completed well, the interference caused by the lack of consideration of the power supply and ground wire will degrade the performance of the product. When wiring, try to widen the width of the power supply and ground wire. It is best The ground wire is wider than the power wire, and their relationship is: ground wire>power wire>signal wire. For the PCB of the digital circuit, a wide ground wire can be used to form a loop, that is, to form a ground network (this method cannot be used for circuits). Use a large-area copper clad layer as the ground wire, and connect the unused places to the ground on the printed board as the ground wire. Or make a multi-layer board, the power supply and ground wire each occupy one layer.
Co-grounding of Digital and Circuits
Co-ground processing of digital circuits and circuits: When digital circuits and circuits coexist, the wiring needs to consider the mutual interference between them, especially the noise interference on the ground. The frequency of the digital circuit is high, and the sensitivity of the circuit is strong. For the signal line, the high-frequency signal line should be as far away from the sensitive circuit device as possible. For the ground line, the entire PCB has only one port for external connection, so it must be The problem of digital and common ground is dealt with inside the PCB, and the digital ground and ground inside the board are actually separated. The ground is shorted a bit to the ground, note that there is only one connection point.
Signal line distribution layer
The signal line is laid on the power (ground) layer: when wiring in a multi-layer printed board, since there are not many lines left in the signal line layer, adding more layers will cause waste and increase production. The workload and cost increase accordingly. In order to solve this contradiction, wiring on the electrical (ground) layer can be considered. The power layer should be considered first, and the ground layer second. Because it is best to preserve the integrity of the formation.
signal flow design
When designing the PCB layout, the design principle of placing the signal in a straight line along the signal flow direction should be fully followed, and try to avoid going back and forth.
Layout Design Suggestions
1. The driver chip and the power MOSFET are placed as close as possible;
2. The vcC-GND(cvcc) / vB-vS(CBS) capacitor should be as close to the chip as possible;
3. Add a certain number of vias to the heat dissipation pad of the chip and connect it to GND (increase heat dissipation and reduce parasitic inductance);
4. The GND wiring is directly connected to the MOSFET source (source), and avoids overlapping with the high current path between the source (source) and the drain (d rain). coincide);
5. The HO/LO wiring should be as wide as possible (60mil-100mil, the driving current is relatively high, and the influence of parasitic inductance can be reduced);
6. The LIN/HIN logic input ports should be kept away from the HS wiring as far as possible (to avoid excessive voltage swings from interfering with the input signal).
