BCM4414XD1E5135YZZ Datasheet, PDF (22/41 Pages) Vicor Corporation – Isolated Fixed-Ratio DC-DC Converter

BCM4414xD1E5135yzz
VIA BCM Isolation
+HI
VI ChiP
+LO
High voltage side
Low voltage side
VIA HI Side Circuit
-HI
SELV
VIA LO Side Circuit
-LO
RI
BI
PE
FI
Figure 26 — BCM in a VIA package after final assembly
Filtering
The BCM in a VIA Package has built-in single stage EMI filtering
with hot-swap circuitry located on high voltage side. Typical test
set-up block diagram for conducted emissions is shown in
Figure 27. Hot-swap circuitry provides inrush current limiting
through the MOSFET.
Further, along with internal ceramic capacitance, it reduces the
voltage ripple. External LO side filtering can be added as needed.
Ceramic capacitance can be used as a LO side bypass for this
purpose. Moreover, along with hot-swap circuitry, it protects the
VIA from overvoltage transients imposed by a system that would
exceed maximum ratings and induce stresses. VIA HI side and LO
side voltage ranges shall not be exceeded. An internal overvoltage
function prevents operation outside of the normal operating HI
side range. Even when disabled, the VIA is exposed to the applied
voltage and the VIA must withstand it.
Given the wide bandwidth of the VIA, the source response
is generally the limiting factor in the overall system response.
Anomalies in the response of the source will appear at the LO side
of the module multiplied by its K factor.
Total load capacitance at the LO side of the VIA shall not exceed
the specified maximum for correct operation of it in startup and
steady state conditions. Owing to the wide bandwidth and small
LO side impedance of the VIA, low frequency bypass capacitance
and significant energy storage may be more densely and efficiently
provided by adding capacitance at the HI side of the VIA. At
frequencies less than 500KHz, the VIA appears as an impedance of
R_LO between the source and load.
Within this frequency range, capacitance at the HI side appears as
effective capacitance on the LO side per the relationship defined
in Eq. (15).
This enable a reduction in the size and number of capacitors used
in a typical system.
C_HI
C_LO =
K²
(15)
DC
Power
Supply
Screen
Room /
Filters
EMI
Receiver
LISN
LISN
+HI
+LO
Single
VIA BCM
(DUT)
–HI
–LO
Load
Figure 27 — Typical test set-up block diagram for
Conducted Emissions
Hot Swap
Many applications use a power architecture based on a 380V_DC
distribution bus. This supply level is emerging as a new standard
and efficient means for distributing power through boards,
racks and chassis mounted Telecom and Datacom system. The
interconnect between the different modules is accomplished with
a backplane and motherboard. Power is commonly provided to the
various module slots via a 380V_DC distribution bus.
Removing the faulty module from the rack is relatively easy,
provided the remaining power modules can support the step
increase in load. Plugging in the replacement module has
more potential for problems, as it will present an uncharged
capacitor load and draw a large inrush current. This could cause a
momentary, but unacceptable interruption or sag to the backplane
power bus if not limited. The problem can also arise if ordinary
power module connectors are used, since the connector pins will
engage and disengage in a random and unpredictable sequence
during insertion and removal.
Hot swap or hot plug is the highly desirable feature in many
applications, but it also creates several issues that must be
addressed in the system design. A number of related phenomena
occur with a live insertion and removal event, including bouncing,
arcing between HI side connector pins, larger voltage and current
transients. Hot swap circuitry in the converter modules protects the
module and the rest of the system from the problem associated
with live insertion.
To meet the maintenance, reconfiguration, redundancy and system
upgrade, this new BCM module is being designed to address the
function of hot-swapping at the 380V_DC distribution bus. This new
module provides a high level of integration for DC-DC converters in
380V_DC distributions, saving the system designer design time and
critical board space. Hot swap circuitry as shown in
Figure 28 uses an active MOSFET switching device in the HI side
line. During insertion, the MOSFET is driven into a resistive state to
limit the inrush current, and then when the inserted module’s HI
side capacitor has charged, the MOSFET becomes fully conductive
to avoid the voltage drop losses. Performance verification is further
illustrated through scope plots of circuit’s response to various live
insertion events.
BCM^® in a VIA Package
Page 22 of 41
Rev 1.4
09/2016
vicorpower.com
800 927.9474