REV. OCT 24, 2003
Page 10 of 12
HHS6
DC
DC Series Data Shee
48Vdc In
ut, 6
m
Hal
Brick Converte
Optional Positive-Trim (–T, P/N suffix)
The trim feature allows the user to adjust the output
voltage from its nominal value.
The HHS60 positive-trim (-T) models trim up with a
resistor from the Trim (#7) pin to the +Sense (#8) pin
and trims down with a resistor from the Trim pin to
the –Sense (#6) pin as shown in the Figure 17.
Figure 17. HHS60 Series Positive Trim Schematic
The equations below determine the trim resistor
value required to achieve a ∆V change in the output
voltage.
100
Rtrim-dn = (-------- - 2) kΩ
∆%
Vo*(100+∆%) (100+2*∆%)
Rtrim-up = (-------------------- - ------------------) kΩ
1.225*∆% ∆%
where ∆V% is the output voltage change expressed
in percent of the nominal output voltage, Vout.
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 the limits defined within the
“
Features” section above.
4. Either Rup or Rdown should be used to adjust the output
voltage according to the equations above. If both Rup and
Rdown are used simultaneously, they will form a resistive
divider and the equations above will not apply
Safety Considerations
The HHS60 Series converters feature 1500 Volt DC
isolation from input to output. The input to output
resistance is greater than 10MOhm. 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 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.
The HHS60 Series converters have no internal fuse.
An external fuse must be provided to protect the
system from catastrophic failure, as illustrated in
figure 15. Refer to the “Input Fuse Selection for
DC/DC converters” application note on www.power-
one.com for proper selection of the input fuse. 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 HHS60 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
