BCM4414xD1E2663yzz
Dielectric Withstand
ZHI_EQ1
ZLO_EQ1
The chassis of the BCM in a VIA package is required to be
connected to Protective Earth when installed in the end application
and must satisfy the requirements of IEC 60950-1 for
Class I products.
BCM®1
R0_1
VLO
VHI
ZLO_EQ2
The BCM in a VIA package contains an internal safety approved
isolating component (ChiP) that provides Reinforced Insulation from
high voltage side to low voltage side. The isolating component is
individually tested for Reinforced Insulation from the high voltage
side to the low voltage side at 4242VDC prior to final assembly
of the VIA. The Reinforced Insulation can only be tested on the
completed VIA assembly at Basic Insulation values, as specified
in the electric strength Test Procedure noted in clause 5.2.2 of
IEC 60950-1.
ZHI_EQ2
BCM®2
R0_2
+
Load
DC
ZLO_EQn
BCM®n
R0_n
ZHI_EQn
Test Procedure Note from IEC 60950-1
“For equipment incorporating both REINFORCED INSULATION and
lower grades of insulation, care is taken that the voltage applied
to the REINFORCED INSULATION does not overstress BASIC
INSULATION or SUPPLEMENTARY INSULATION.”
Figure 24 — BCM module array
Fuse Selection
Summary
The final VIA assembly provides basic insulation from the high
voltage side to case, basic insulation from the high voltage side to
the low voltage side and functional insulation from low voltage
side to case. The case is required to be connected to protective
earth in the final installation. The protective earth connection can
be accomplished through a dedicated wiring harness (example: ring
terminal clamped by mounting screw) or surface contact (example:
pressure contact on bare conductive chassis or PCB copper layer
with no solder mask).
In order to provide flexibility in configuring power systems, BCM in
a VIA package modules are not internally fused. Input line fusing
of BCM products is recommended at the system level to provide
thermal protection in case of catastrophic failure.
The fuse shall be selected by closely matching system
requirements with the following characteristics:
ꢀnCurrent rating
(usually greater than maximum current of BCM module)
The ground connection of the top case must be 3 orders of
magnitude more resistive than the current return connection to
the bottom case. The construction of the VIA can be summarized
by describing it as a “Class II” component installed in a “Class I”
subassembly. The insulation from the high voltage side to the low
voltage side can only be tested at basic insulation values on the
fully assembled VIA product.
ꢀnMaximum voltage rating
(usually greater than the maximum possible input voltage)
ꢀnAmbient temperature
ꢀnNominal melting I2t
ꢀnRecommend fuse: 10A Littelfuse 505 Series or
10A Littelfuse 487 Series (HI side)
ChiP Isolation
Reverse Operation
BCM modules are capable of reverse power operation. Once the
unit is started, energy will be transferred from the low voltage
side back to the high voltage side whenever the low voltage side
exceeds VHI • K. The module will continue operation in this fashion
as long as no faults occur.
High voltage side
Low voltage side
SELV
The BCM4414xD1E2663yzz has not been qualified for continuous
operation in a reverse power condition. However, fault protections
that help to protect the module in forward operation will also
protect the module in reverse operation.
RI
Transient operation in reverse is expected in cases where there is
significant energy storage on the low voltage side and transient
voltages appear on the high voltage side.
Figure 25 — ChiP before final assembly in the VIA
BCM® in a VIA Package
Page 22 of 43
Rev 1.1
01/2018
VICOR [ VICOR CORPORATION ]
