Cellular Module: Design Rules and Process Limits A product that connects over a mobile network carries a radio transmitter and a power amplifier on the same board as its logic. Cellular module board design is mostly about the supply, the antenna and the certification, because the radio itself is inside…

Smartphone Pcb: Preparation, Placement and Process Control A handset board packs several radios, a display, cameras and a battery into a space smaller than a card. Smartphone pcb design is a planning problem before it is a drawing problem, because the routing capacity has to be proven before the layout…

Series Resistor: Preparation, Placement and Process Control A light emitting diode needs its current limited, and the cheapest way to do that is a series resistor. Getting the value right is arithmetic, but choosing where to put the resistor and how to rate it takes a little more thought. Why…

LIN Bus: Preparation, Placement and Process Control A LIN bus is a low speed single wire network used inside a vehicle, mostly to connect switches, sensors and small actuators to a body controller. The transceiver is the interface between the protocol controller and the wire, and it has to survive…

Mixed Flowing Gas: Preparation, Placement and Process Control Salt spray measures resistance to chloride. It says almost nothing about what happens in an office, a data centre or an industrial cabinet, where the aggressive species are sulfur compounds and nitrogen oxides at concentrations far too low to see. Mixed flowing…

RS-422: Preparation, Placement and Process Control RS-422 is a balanced interface that carries a single signal in one direction over a pair of conductors. It is the simplex counterpart of the bidirectional bus that most people know, and it is still used where a one way link has to travel…

Projector Mainboard: Design Rules and Process Limits A compact projector fits a display engine, a battery and a processor into a space the size of a book. Projector mainboard design is dominated by the light source, because the led driver and its power loop set the size, the heat and…

NVR Mainboard Design for Multi Channel Video Recording A network video recorder is a computer whose workload is almost entirely video, and its board is designed around that fact. NVR mainboard design means balancing decode channels, storage bandwidth and display outputs against a power budget that has to hold for…

From SoC Datasheet to Board Design Decisions A processor datasheet runs to hundreds of pages, and most of the board is decided by a few tables inside it. Reading it in a defined order turns a datasheet into a set of design decisions rather than a reference to search. Read…

Gold Finger: Design Rules and Process Limits An edge connector uses the board itself as the plug. The contacts are copper fingers plated with a wear resistant metal, and they slide into a mating socket when the card is inserted. The finger geometry, the plating stack, and the bevel at…