Description

<p style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> Ways to reduce noise and&nbsp;electromagnetic interference: </p> <p style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (1) Prefer low-speed chip to high-speed; high-speed chip is used in key places. </p> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (2) By a string of resistance, reducing and controlling the rate of change when circuits go up and down. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (3) Provide relay with some form of damping. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (4) Use the lowest frequency clock that meets the system requirements. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (5) The clock generator is as close as possible to the device using the clock. The shell of Quartz crystal oscillator should be grounded. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (6) Circle up clock with the ground wire and the clock line is as short as possible. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (7) I/O drive circuit should leave the edge of the printing plate instantly. The signal goes into the printed circuit board and from the high noise zone should be added to filter, reducing the signal reflection by stringing termination resistor. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (8) MCD useless end should be high, or ground, or defined as the output, and the end of power supply in integrated circuit need to be grounded, do not vacant. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (9) Do not make the input end of idle gate circuit vacant; positive input termination of idle op amp is grounded and negative input termination connects output. </div> <p style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (10) Try to use 45 fold lines instead of 90 fold lines in PCB to reduce the external launch and coupling from high-frequency signal. </p> <p style="text-align:center;margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> <img src="https://file.allpcb.com/bbs/17/05/15/140855374.png" alt="" /> </p> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (11) Printed circuit board is distinguished by the frequency and current switching characteristics, the noise components and non-noise ones should be far. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (12) single-sided and double-sided board are adopting single-point power supply and single-point grounding; power and ground wires is as thick as possible, using multi-layer board to reduce the power supply and capacitive inductance if you are not sensitive to money. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (13) Clock, bus and chip select should be away from I/O lines and connectors. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (14) Analog voltage input line, notice the voltage side stays away from the digital circuit signal lines, especially to the clock. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (15) To the A/D class devices, digital and analog part would rather unite rather than cross. </div> <p style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (16) The interference of clock line which is perpendicular to the I/O line is smaller than the parallel and the clock component pin is far from I/O cable. </p> <p style="text-align:center;margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> <img src="https://file.allpcb.com/bbs/17/05/15/141206372.png" alt="" /> </p> <p style="text-align:left;margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (17) Component and decoupling capacitor pins are as short as possible. </p> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (18) The key line should to be as thick as possible with protection ground on both sides. High-speed line is short and straight. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (19) Noise-sensitive lines do not parallel to high-current, high-speed switching lines. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (20) Do not route below quartz crystal and noise-sensitive devices. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (21) Do not form a current loop around weak signal circuit and low frequency circuit. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> (22) Do not form a loop for any signal, if unavoidable, make loop area as small as possible. </div> <div class="e_p" style="margin:0px;padding:0px 0px 20px;border:0px;outline:0px;box-sizing:initial;line-height:20px;font-size:14px;font-family:Arial, 'microsoft yahei', 'Times New Roman', '\5 b8b\4 f53';white-space:normal;background-color:#FFFFFF;"> <span style="display:none;"></span><br /> </div> <span style="display:none;"></span> <p> <br /> </p>