BCM48BH120120B00 Datasheet, PDF (13/16 Pages) Vicor Corporation – Fixed Ratio DC-DC Converter

BCM48BH120T120B00
7.0 CURRENT SHARING
The SAC™ topology bases its performance on efficient transfer
of energy through a transformer, without the need of closed
loop control. For this reason, the transfer characteristic can be
approximated by an ideal transformer with some resistive drop
and positive temperature coefficient.
This type of characteristic is close to the impedance characteristic
of a DC power distribution system, both in behavior
(AC dynamic) and absolute value (DC dynamic).
When connected in an array (with same K factor), the BCM^®
module will inherently share the load current with parallel
units, according to the equivalent impedance divider that the
system implements from the power source to the point of load.
It is important to notice that, when successfully started, BCM
converters are capable of bidirectional operations (reverse
power transfer is enabled if the BCM converter input falls
within its operating range and the BCM converter is otherwise
enabled). In parallel arrays, because of the resistive behavior, cir-
culating currents are never experienced, because of energy con-
servation law.
General recommendations to achieve matched array impedances
are (see also AN016 for further details):
• to dedicate common copper planes within the PCB to
deliver and return the current to the modules
• to make the PCB layout as symmetric as possible
• to apply same input/output filters (if present) to each unit
Figure 17 — BCM^® module array
BCM^® Bus Converter
Page 13 of 16
Rev 1.2
07/2015
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