Schematic Design Considerations

<Schematic design is the embodiment of chaos schematic design ideas can only represent chaos>

1. Schematic of the mark

Schematics is an important tool for electronic design engineers, design engineers communicate with the PCB, when the board complexity to a certain extent, by electronic design engineers can not detail all of the language should be noted that PCB design PCB design engineers are told, in this case under the principle of icon Note will be an important tool, on the one hand the PCB design engineers to design requirements at a glance, on the other hand can also serve as a reminder of the role of electronic design engineers, to avoid missing some key details in the design / test.

2. Schematic of context

Context clear schematics help to improve the efficiency of debugging, testing, production and other aspects.
(1) Schematic home, it should draw the general framework drawing board.
If the board design more complex, but also necessary, to draw a block diagram of the power architecture, clock topology, the reset link topology on a subsequent page, breaking the link topology, like the boundary scan chain of FIG. If larger panel interface board, the proposed increase for a display panel. If I2C bus topology is more complex, a need to increase the address of the I2C device for each annotation.
Voltage and current values (2) near the output end of the schematic diagram of the power supply circuit, the power sources should be marked, which helps PCB engineers grasp what should branch bold traces, vias increase the processing power and the like.
(3) the current path denoted key. After marked on the schematic, PCB designers in favor of the path of attention, do take the bold line treatment.
(4) to take into account the requirements in the PCB design of the discharge position when the device layout schematic drawing. For example, the impedance matching circuit / static / EMI protection circuits have certain requirements for the deployment position of the device, which needs to be reflected in the schematic drawing of FIG.
(5) The capacitance of the order of drawing the PCB capacitance filtering circuit schematic. For example, a filter circuit according to 3.3V, on the PCB, 1uF capacitor should be placed in the outermost, followed 100uF / 10uF / 0.1uF, is required in order to draw on the principle embodied in FIG.
It should be marked on the key signal (6) Schematic rate / wiring layer, if there is a relationship between the signal trace length line, marked also suggested in principle in FIG.
(7) should be marked Schematic high heat and heat-sensitive components, if special requirements are placed, may be annotated on the schematic.
(8) for key components, should be marked on the schematic Number / precision / dimension corresponding information. The key device comprises a fuse resistor / voltage dividing circuit, the filter circuit of the power supply inductance / beads / capacitance, a power supply circuit and the switching frequency of the voltage adjusting resistor / the MOSFET / diode / resistor voltage sampling and the like.
(9) diagram, the jumper selected respond welding / empty mount devices disposed annotate method.
(10) on the schematic, the order should be marked on the connector and the backplane connector / panel LED indicator.
(11) the schematic version management, detailed records of each design change point changes as well as changes and other reasons.