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Output modules that are not delivering current will typically sink a small amount of current from the other outputs, but this
will not exceed -6% of each modules maximum rated current.
Typically, system reliability is reduced as the higher adjusted modules will do most of the work with the lower adjusted
modules only delivering current during peak load demand.
Share parallel mode
In Share parallel mode, the outputs are paralleled as before and the I
ctrl
pin for each module is connected together as shown
in the diagram below.
Connecting the I
ctrl
pins together forces all the outputs to deliver the same current, ensuring that the system reliability is
maximised and the work load is distributed evenly across all paralleled modules.
In this mode the lowest adjusted output module will determine the actual output voltage and all higher adjusted outputs will
reduce their voltage. There may be a small amount of circulating current between the modules, approximately 6%
of the
maximum rated current for each module.
The current output signal (I
ctrl
) can still be used to measure the output current but it must be scaled by N, where N is the
number of paralleled modules.
Paralleling across multiple chassis
Paralleling across multiple chassis is not possible without external protection (such as external diodes or controlled MOSFETs)
to prevent circulating currents between each chassis. Failure to provide such protection may result in damage to the units.
Consult Roal Electronics for details on how best to implement such applications.
Where units are paralleled across multiple chassis, the outputs in each chassis will not be synchronised and the peak-to-peak
output ripple may contain beat frequencies in the audio spectrum.
WARNING!
Care must be taken to avoid differential voltages between the negative power output terminals of the
paralleled modules as this can cause errors at the control pins. To avoid this, it is recommended that a low
impedance connection be made between the negative power terminals close to the PSU output and cables
then connected from this common point to the load.
