HBC25ZH-NT Datasheet, PDF (5/7 Pages) Power-One – HBC DC-DC Series Data Sheet 300-Watt Half-Brick Converters

HBC DC-DC Series Data Sheet
300-Watt Half-Brick Converters
to receive safety agency approval, certain rules
must be followed in the design of the system. In
particular, all of the creepage and clearance
requirements of the end-use safety requirements
must be observed. These documents include
UL60950 - CSA60950-00 and EN60950, although
other or additional requirements may be needed
for specific applications.
Figure 3. HBC Series Positive Trim Schematic
The equations below determine the trim resistor value
required to achieve a ∆V change in the output voltage.
Rup
=
⎜⎛
⎝
Vo(100 + ∆%)
1.225∆%
−
(100 + 2∆%)
∆%
⎟⎞kΩ
⎠
Rdown
=
⎜⎛
⎝
100
∆%
−
2) ⎟⎞kΩ
⎠
where ∆V% is the output voltage change expressed in
percents of the nominal output voltage, Vo.
Notes:
1. When the output voltage is trimmed up, the output power from
the converter must not exceed its maximum rating. The power is
determined by measuring the output voltage on the output pins,
and multiplying it by the output current.
2. In order to avoid creating apparent load regulation degradation, it
is important that the trim resistors are connected directly to the
remote sense pins, and not to the load or to traces going to the
load.
3. The output voltage increase can be accomplished by either the
trim or by the remote sense or by the combination of both. In
any case the absolute maximum output voltage increase shall
not exceed 10% of the nominal output voltage
Safety Considerations
The HBC Series converters feature 1500 Volt DC
isolation from input to output. The input to output
resistance is greater than 10MΩ. These converters are
provided with basic insulation between input and output
circuits according to all IEC60950 based standards.
Nevertheless, if the system using the converter needs
The HBC Series converters have no internal fuse.
The external fuse must be provided to protect the
system from catastrophic. The user can select a
fuse based upon the highest inrush transient at
the maximum input voltage and the maximum
input current of the converter, which occurs at the
minimum input voltage. Both input traces and the
chassis ground trace (if applicable) must be
capable of conducting a current of 1.5 times the
value of the fuse without opening. The fuse must
not be placed in the grounded input line, if any.
In order for the output of the HBC Series
converter to be considered as SELV (Safety Extra
Low Voltage) or TNV-1, according to all IEC60950
based standards, one of the following
requirements must be met in the system design:
• If the voltage source feeding the module is
SELV or TNV-2, the output of the converter
may be grounded or ungrounded.
• If the voltage source feeding the module is
ELV, the output of the converter may be
considered SELV only if the output is
grounded per the requirements of the
standard.
• If the voltage source feeding the module is a
Hazardous Voltage Secondary Circuit, the
voltage source feeding the module must be
provided with at least basic insulation
between the source to the converter and any
hazardous voltages. The entire system,
including the HBC converter, must pass a
dielectric withstand test for reinforced
insulation. Design of this type of systems
requires expert engineering and under-
standing of the overall safety requirements
and should be performed by qualified
personnel.
REV. DEC 15, 2003
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