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V•I Chip Bus Converter Module

B048F160T24

Rev. 2.5

Page 10 of 12

V•I Chip Bus Converter Module

Parallel Operation

The BCM will inherently current share when operated in an array. Arrays

may be used for higher power or redundancy in an application.

Current sharing accuracy is maximized when the source and load

impedance presented to each BCM within an array are equal. The

recommended method to achieve matched impedances is to dedicate

common copper planes within the PCB to deliver and return the current

to the array, rather than rely upon traces of varying lengths. In typical

applications the current being delivered to the load is larger than that

sourced from the input, allowing traces to be utilized on the input side

if necessary. The use of dedicated power planes is, however, preferable.

The BCM power train and control architecture allow bi-directional

power transfer, including reverse power processing from the BCM

output to its input. Reverse power transfer is enabled if the BCM input

is within its operating range and the BCM is otherwise enabled. The

BCM’s ability to process power in reverse improves the BCM transient

response to an output load dump.

Input Impedance Recommendations

To take full advantage of the BCM capabilities, the impedance

presented to its input terminals must be low from DC to approximately

5 MHz. The source should exhibit low inductance (less than 100 nH)

and should have a critically damped response. If the interconnect

inductance exceeds 100 nH, the BCM input pins should be bypassed

with an RC damper (e.g., 47 µF in series with 0.3 ohm) to retain low

source impedance and stable operations. Given the wide bandwidth of

the BCM, the source response is generally the limiting factor in the

overall system response.

Anomalies in the response of the source will appear at the output of

the BCM multiplied by its K factor. The DC resistance of the source

should be kept as low as possible to minimize voltage deviations. This is

especially important if the BCM is operated near low or high line as the

over/under voltage detection circuitry could be activated.

Input Fuse Recommendations

V•I Chips are not internally fused in order to provide flexibility in

configuring power systems. However, input line fusing of V•I Chips

must always be incorporated within the power system. A fast acting

fuse should be placed in series with the +In port.

Application Notes

For BCM and V•I Chip application notes on soldering, thermal

management, board layout, and system design click on the link below:

http://www.vicorpower.com/technical_library/application_information/chips/

Application Note