Overview
An industrial control cabinet or an instrument needs one or more clean DC rails from the mains, and the rails must hold steady as the load and the temperature change. Cincon provides the whole chain: an open-frame AC-DC supply for the mains-to-DC stage and an isolated DC-DC converter for a lower rail, and BeiLuo supplies them with genuine traceability and FAE support. This page shows how the parts fit together in an industrial control design.
The Main DC Rail
The first stage is an open-frame AC-DC supply that converts the mains into the main DC rail, usually 12 V or 24 V. A Cincon CFM series supply gives a universal input of about 90 V to 264 V AC, a compact 2x4 inch footprint, an industry-standard pin-out and a continuous short-circuit protection, and it meets the EN55032 Class B emission and the IEC/EN/UL 62368-1 safety standard on its own, so a separate filter is not always needed. Choose the power with margin above the load and confirm the derating at the highest ambient, because an open-frame supply depends on the free air around it.
Choosing the Power and the Cooling
Add the load of every rail on the supply, add margin for the start-up and the lifetime, and choose the next standard wattage. The smaller CFM parts cool by convection and the larger parts use a baseplate or a forced air path, so choose by the power and the enclosure. Confirm the derating at the ambient, because a supply in a warm cabinet delivers less than its rating at the nominal temperature.
The Isolated Lower Rail
A control board often needs a lower rail, such as 5 V, that is isolated from the main bus. A Cincon EC-series DC-DC converter, such as the EC7AW-24S05 for 10 W or the EC3AW02 for 3 W, converts the bus into a regulated isolated rail, so the logic is separated from the bus and a ground loop is broken. The wide 4:1 input range lets the module accept a varying bus and hold the output, which suits an industrial 24 V bus or a battery, and the isolated output protects the sensitive logic from the bus.
Layout of a DC-DC Module
Keep the input capacitor close to the module, follow the recommended pi filter for the conducted emissions and keep the switching loop small, and use a ground plane that respects the isolation between the input and the output. These steps keep the rail clean and the emissions within the limit.
EMC and Protection
The input of the equipment must meet the conducted-emissions limit, and the Cincon CFM series meets the Class B limit on its own, so the EMC is often designed in. The isolation of the DC-DC module and the protection of both parts, such as the short-circuit and the over-voltage protection, keep the design safe during a fault and improve the reliability.
Thermal Design
Compute the loss of the supply and the module, choose the cooling and the mounting from the thermal path, and measure the case and the ambient temperature at the worst case. A cooler supply and module last longer, so leave thermal margin.
Verification
Validate the design on the bench by measuring the efficiency and the derating of the supply at the worst-case load and ambient, by checking the ripple and the transient of each rail and by measuring the conducted emissions with the real load. Our FAE team can review the measurements and the layout, so the power design meets its target in the product as well as on the bench.
Getting Help
Send your rails, the current on each, the input and the environment to our FAE team, and we will propose a supply and the DC-DC modules, help size the power and the cooling and review the filtering and the EMC. BeiLuo holds mainstream Cincon parts in regional stock and ships them with an import declaration, a certificate of origin and a RoHS compliance file, so an industrial power design can move from prototype to production without a supply gap.