ESD Protection in Circuit Design How a Discharge Reaches the Circuit An electrostatic discharge arrives at a connector, a button, a seam or a cable, and from there it travels through the product to find a return. The current is short in duration but very high, and its path through…

Grounding Strategy for Mixed Signal Boards The Question and the Argument Grounding a mixed signal board is one of the most argued topics in layout, because both of the common answers can be defended. One camp splits the plane into an analogue part and a digital part and joins them…

EMC Design for PCB Layout EMC Starts on the Board Electromagnetic compatibility is usually treated as a test that happens at the end of a project, and by then most of the cost is already committed. The behaviour that the test measures is decided by the layout: the size of…

Crosstalk and Signal Spacing How Crosstalk Happens Crosstalk is energy from one net appearing on another. It couples in two ways: capacitively, through the electric field between the conductors, and inductively, through the magnetic field that the current produces. Capacitive coupling injects a current into the victim that is proportional…

Mixed Signal ADC Layout and Grounding What the Converter Needs A high resolution converter resolves a voltage in the microvolt range, and the layout has to deliver that voltage to the input without adding noise or an error. The two things that ruin a converter’s performance are a noisy reference…

DC-DC Converter Layout Rules The Layout Sets the Performance A switching converter’s efficiency, its output noise and its electromagnetic behaviour are decided largely by the layout. The components are usually chosen from a reference design, and the difference between a good and a poor result is usually the placement and…

Battery Charging Circuit Layout Why the Layout Matters A battery charger is a power converter with a current limit and a control loop, and its behaviour depends on the layout as much as on the component selection. The charging current is set by a sense resistor and its connection, the…

LED Board Design and Thermal Layout An LED Board Is a Thermal Design An LED converts only part of its input into light; the rest becomes heat, and that heat has to leave the junction or the device will run hotter, produce less light and fail sooner. The board is…

PCB Requirements for Medical Devices What Makes Medical Different A medical device is regulated, and the regulation reaches the board through the documentation and through the requirements it has to meet. The product may be in contact with a patient, it may be connected to a patient while powered, and…

Automotive Electronics and PCB Requirements What Makes Automotive Different An automotive electronic module operates in a harsh environment, is expected to last the life of the vehicle and, where it affects safety or emissions, is subject to a formal qualification and traceability regime. The temperature range is wide, the vibration…