pcb design

Because many things can affect transmission lines, EMI problems can occur. In order to reduce these  problems, good PCB design is important and with some simple design rules, the PCB designer can  minimize these problems. It is important to make prudent decisions during new circuit design, like the minimum number of layers. The easiest way to get a good, new design is to copy the recommended design from the TI evaluation modules (EVM). A good PCB layout starts with the circuit design. Do not postpone considerations about the layout. One of the most important aspects affecting the layout is the location of each functional block. Keep their devices and their traces together. PCB Considerations During the Circuit Design · What is the highest frequency and fastest rise time in the system? · What are the electrical specifications at the inputs and outputs of the sinks and sources? · Are there sensitive signals to route – for example, think about controlled impedance, ter...

What are the main benefits of rectangular connectors? When compared to circular connectors rectangular connectors are generally less expensive,have shorter lead times and are more easily customizable.Rectangular Connectors are also have better grounding system providing more protection against overvoltage and have a visual polarization for easy mating. They can also be easily keyed. Key advantages for using rectangular connectors over circular includes: 1. Off-the-self modules for easy custom designs for any application. 2. superior space efficiency. 3. more termination option-crimp,solder, screw terminal, others. 4. More locking options-single or double-lever or push button. 5. Ability to connect to other device such as PCB. 6. Greater contact Density Possible. 7. Greater cabling Flexibility- Top,Dual,side or angled cable entry. 8. Surface mount,Panel mount and cable to cable compability. 9.lower cost. 10.Better protection against over voltage. 11. easier Visual matin...

What are PCB Connectors? There are many different types of PCB connectors, which is not surprising, given the many different types of components and devices that are attached with these connectors. Some printed circuit board connectors are designed to operate under stressful conditions, to support relatively heavy loads and to provide stability and safety under those circumstances. Other printed circuit board connectors are much more delicate. Printed circuit board connectors often come in kits, with both ends of the connection and the hardware required to install the connector to the printed circuit board. Some printed circuit board connectors can only work with one type of a connector and others are designed to work with stripped wires, making it possible to hook up devices generically, without relying upon a specific type of connector to complete the circuit. TYPES OF PCB CONNECTORS-- -- Rectangular connectors-- Rectangular connectors are used widely in modular ma...

AGND - Analogue Ground - separate ground for analogue signals. CAN - Controller Area Network - a bus that is manly used in automotive and industrial environment. DRC - Design Rule Check - a tool for checking whether all design rules are satisfied in a CAD tool. DSI - Display Serial Interface. EDA- Electronic Design Automation - software for schematic capture and PCB layout (CAD or ECAD). EMC - Electromagnetic Compatibility -theory of unintentional generation, propagation, and reception of electromagnetic energy. EMI- Electromagnetic Interference - high frequency disturbances. eMMC - Embedded Multi Media Card - flash memory combined with MMC interface controller in a BGA package,used as internal flash memory. ESD - Electrostatic Discharge - high voltage spike or spark that can damage electrostatic-sensitive devices. GBE - Gigabit Ethernet - Ethernet interface with a maximum data rate of 1000Mbit/s. GND - Ground GPIO - Ge...

There are three reasons to use differential pairs in a digital or analog signal path. Where the ground connections between the ends of the signal path are poor. The most important one is that the ground connection between the two ends of the signal path can be  very poor and data quality will not be compromised.Compare this to a single-ended signal path such as LVCMOS, where the signal arriving at the receiver is compared to a reference level in the receiver. If the grounds between the two ends are offset, the logic levels will be offset and one or the other of the two logic levels is compromised. This ability to “ignore” ground offsets has been the backbone of the wired Internet from the onset. In the case of Ethernet,the two ends of these links are transformer coupled. Where there is significant attenuation along the signal path. A second reason to use differential signaling is that the link can suffer substantial attenuation...

In its most basic form, a differential pair is made up of two transmission lines that have  equal and opposite polarity signals travelling on them. The property that these two signals  have in common is that they are equal and opposite and they are tightly timed to each other. Beyond these two characteristics there are no other properties that matter when a design uses  differential pairs. Maintaining the equal and opposite amplitude and timing relationship is the  guiding concept when using differential pairs.                       figure 1 Figure 1 is a typical CMOS differential pair driver and receiver pair. It is the usual circuit  used in LVDS (low voltage differential signaling) type signaling protocols.                                figure 2 As can be seen from Figure 1, there are two indepe...

Capacitors (and inductors) have the ability to store electrical energy, inductors store energy as a magnetic field around the component, but the capacitor stores electrical energy directly, as an ELECTROSTATIC FIELD created between two metal "plates". Basic Circuit symbols for capacitors • High Voltage Electrolytic- used in power supplies.  • Axial Electrolytic; lower voltage smaller size for general purpose where large capacitance values are needed.  • High Voltage disk ceramic; small size and capacitance value, excellent tolerance characteristics.  • Metalised Polypropylene; small size for values up to around 2µF good reliability.  • Sub miniature Multi layer ceramic chip (surface mount) capacitor. Relatively high         capacitance for size achieved by multiple layers, effectively several capacitors in parallel.  Uses of Capacitors. Decoupling --The most prevalent use of capacitors ...

Pcb

PCB layout is a means to combine your artistic side and your creative skills with the power of automation. I always say that if a PCB design looks good, it will probably work well. However, neatness in routing often leads to unwanted crosstalk as trace segments are routed in parallel for long distances. Interactive Placement  - To obtain a high route-completion rate, component placement is extremely important. If the board is difficult to route, it may just be the result of poor placement, slots/gates positioned all over the board, or perhaps the sequence of pins on components are flipped. We need to help the router as much as possible by opening route channels and providing space for vias.  Interactive placement is best done by cross-probing and dragging the components one-by-one from the schematic to place on the PCB—taking functionality and design constraints into account.  During placement, consideration should not only be given to routing, but also...