Technical Specification
S25-48-3.3, S25-48-3.3N
48Vin 3.3Vout 7A
•
BTCPower
TM
Application Considerations
Input source Impedance
The unit has been designed to be stable with no
external capacitor when used in a low inductance
input and output circuit.
However in many applications, the inductance
with the distribution from the power source to the
input of the unit can affect the stability of the unit.
An external capacitor across the input will
improve the stability of the unit. Also in many
applications, the user has to use decoupling
capacitors at the output load, to ensure the hold
up time for the load.
Never ground either of the input pins of
the unit without grounding one of the
output pins. This may allow a non-SELV
voltage to appear between the output pin
and ground.
Electromagnetic Compatibility (EMC)
The unit’s conducted emission meets the
requirement of EN55022 Class B Specifications,
so no external input filter is needed unless a
stricter conducted EMI/EMC limitation is required
to satisfy or user has its own requirement on the
input.
Fig 6 shows the measured conducted EMC.
Six-sided metal shields for zero radiate emission.
Safety Requirements (SR)
The unit meets UL/CSA/TUV safety requirements
per UL60950, TUV EN60950 and CSA C22.2
No.60950-00.
Basic insulation is provided
between input and output.
Caution:
The unit does NOT have a fuse inside. The safety
agencies require an external normal-blow fuse to
be used at the input side to achieve maximum
safety. The recommended fuse rating is 2A/100V.
If the input source is non-SELV (ELV or a
hazardous voltage greater than 60 Vdc and less
than or equal to 75 Vdc), for the unit output to be
considered meeting the requirements of safety
extra low voltage (SELV), all of the following must
be met:
•
The input source is to be provided with
reinforced insulation from any hazardous
voltage, including the ac main.
•
The input pins of the unit are not operator
accessible.
•
For the whole system, for safety agencies
requirements, and for the combination of
the unit input side (primary side) and the
output side (secondary side), verify that
under a single fault, hazardous voltages
do not appear at the unit output side
(secondary side).
Fig 6. Conducted EMC (150KHz-30MHz) test result, the
upper trace is the limit of EN55022 Class B specification
Input Transient Withstand (ITW)
The unit can withstand input transient voltage
with 100V/100ms pulse and never be damaged
.
Broadband TelCom Power, Inc. –
1719 S. Grand Avenue, Santa Ana, CA 92705 U.S.A.
P 6 of 11
Tel.: 714-259-4888 • Fax: 714-259-0840 • www.btcpower.com • Email: sales@btcpower.com
PS S25-48-3.3 Rev 3 16-1-04
BTCPOWER [ BROADBAND TELCOM POWER, INC. ]
