Overview
A telecom or a datacom rack runs continuously for years, so its power system must be efficient and reliable, and it must derive several board rails from a common bus. Cincon provides the AC-DC supply for the feed and the wide-input isolated DC-DC converters for the board rails, and BeiLuo supplies them with genuine traceability and FAE support. This page shows how the parts fit together in a telecom and datacom power design.
The Rack Feed
The rack feed converts the mains into a bus, usually 24 V or 48 V, that the boards share. A Cincon CFM series supply such as the CFM60S240 gives a 60 W 24 V output with a universal input, a compact open-frame form and the EN55032 Class B emission on its own, and the higher-power CFM parts reach several hundred watts with an active power-factor correction. The supply cools by convection for the smaller parts and by a baseplate or a forced air path for the larger, so choose by the power and the rack cooling.
The Bus Voltage
A 48 V bus keeps the current low on the backplane and the distribution losses small, while a 24 V bus suits a lower-voltage system. The Cincon EC series covers both with a 2:1 and a 4:1 input range, so a designer can match the converter to the bus and the rail.
The Board Rails
Each board derives its own rails from the bus with an isolated DC-DC converter, so the board is protected from the bus and the ground loop is broken. A Cincon EC3SCW-48S12 accepts an 18-75 V input with a 4:1 range and gives an isolated 12 V rail at about 30 W with an efficiency up to about 91 percent and a low no-load current, and a smaller EC7AW or EC3AW module covers a lower-power rail. Because the modules are compact and board-mount, several fit on one board, so a single bus feed serves the whole card.
Distributed Power Architecture
The distributed approach, one bus and a converter per rail, is common in a telecom rack because it keeps the current low on the bus, isolates the boards from each other and lets each board be tested on its own. The converter is the building block, and the isolation and the layout decide the noise and the reliability.
Efficiency and Thermal
The Cincon EC modules reach an efficiency in the high eighties to low nineties, which keeps the heat down on the board, and the shielded 2x1 inch case helps the EMC. Compute the loss at the working point, plan the thermal path and confirm the derating at the worst-case ambient, because a rack that runs continuously needs the margin.
Protection
The isolated converters include a continuous short-circuit protection and, on many parts, an over-voltage and an under-voltage protection, so a fault on one board does not take the system down. Confirm the protection against the rack requirement.
Verification
Validate the design on the bench by measuring the efficiency and the derating of the supply at the worst case, 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 connected design performs in the product as it does on the bench.
Getting Help
Send your bus voltage, the current on each rail, the input and the environment to our FAE team, and we will propose a supply and the converters, help size the feed and the rails and review the cooling 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 a telecom power design can move from prototype to production without a supply gap.