A USB-C connecotr has two sets of data pins, the plug that will connect to it has just one pair. You route a single differential pair between the connector and your processor as normal (using impedance-controlled routing for the differential pair). At the connector, connect the differential pair to both sets of pins on the […]
Category: General PCB Design
Spark Gaps
You can use PCB traces to create a poor mans spark gap on a PCB really easily. Whilst not as good as a proper device such as a gas discharge tube, they cost nothing as long as you have the PCB space available. Using a 8 thou / 0.2mm gap will create a spark gap that […]
PCB Stackup
Asymmetric Layer Stackup It is best to keep a boards layer stackup symmetric to prevent board warpage. Some manufacturers may be willing to go to the extra effort to fight the warpage from an asymmetric stackup (often by them having to make multiple attempts to get it right for your stackup) but at cost and risk. […]
Via’s
Via Current Rating A general rule of thumb for typical via's (say 0.5mm) passing high currents between layers is to allow 0.5A nominal per via. Bigger hole sizes increase this rating with the larger surface area of the plating through the hole, but for high current connection more smaller vias can beneficial if your copper […]
PCB Track Impedance
Clocked busses often need impedance controlled tracking to avoid the posibility of false clock signals caused by an impedance mismatch. As semiconductor devices have become faster and faster they have become much more susceptible to issues caused by signal noise. The problem relates to any type of clocked interface where a device you will transfer […]
Good PCB Design Checklist
A good list of checks to make before committing the design of a new printed circuit board: EMI & Signal Integrity checks: Are there decoupling capacitors in all areas where there are connectors or via’s, to minimise EMI loop sizes of signals and their return ground path? If not do you need to add some? […]