Ericsson Internal
PRODUCT SPECIFICATION
2 (5)
E
Prepared (also subject responsible if other)
No.
MICMALE
3/1301-BMR 658 Uen
18
Technical Specification
Approved
Checked
Date
Rev
Reference
EN/LZT 146 384 R4A
May 2013
PSKEBC/4D0B0e0ttBy Wsueries Intermediate Bus(ECZHonEvWeNrGte)rs2009-12-16
Input 36-75 V, Output up to 40 A / 252 W
PB3
© Ericsson AB
ceramic capacitors will handle high-frequency dynamic load
Operating information
changes while the electrolytic capacitors are used to handle
low frequency dynamic load changes. Ceramic capacitors will
also reduce any high frequency noise at the load.
It is equally important to use low resistance and low
inductance PCB layouts and cabling.
The recommended absolute maximum value of output
capacitance is 2 000 μF. The user should be aware, however,
that large values of capacitance will affect the ramp-up time of
the DC/DC converter output voltage during
Input Voltage
The input voltage range 36 to 75 Vdc meets the requirements
of the European Telecom Standard ETS 300 132-2 for normal
input voltage range in –48 and –60 Vdc systems,
-40.5 to -57.0 V and –50.0 to -72 V respectively.
At input voltages exceeding 75 V, the power loss will be higher
than at normal input voltage and Tref must be limited to
absolute max 125 °C. The absolute maximum continuous
input voltage is 80 Vdc.
start-up.
Parallel Operation
Turn-off Input Voltage
The converters can be paralleled for redundancy if external o-
ring diodes are used in series with the outputs.
The DC/DC converters monitor the input voltage and will turn
on and turn off at predetermined levels.
The minimum hysteresis between on and off input
voltage is 1.0 V.
Over Temperature Protection (OTP)
The DC/DC converters are protected from thermal overload by
an internal over temperature shutdown circuit.
Remote Control (RC)
When Tref as defined in thermal consideration section
exceeds 125°C the DC/DC converter will shut down. The
DC/DC converter will make continuous attempts to start up
(non-latching mode) and resume normal operation
automatically when the temperature has dropped below the
temperature threshold.
The products are fitted with a
remote control function referenced
to the primary negative input
connection (- In), with positive logic
option available. The RC function
allows the product to be turned
on/off by an external device like a
semiconductor or mechanical
switch. The RC pin has an internal
pull up resistor to + In.
Over Voltage Protection (OVP)
The DC/DC converters have an output over voltage protection
that normally will clamp the output voltage to the OVP
threshold level. If the output voltage should increase to the
OVP threshold level very fast then the DC/DC converter can
shut down and make attempts to start up (non-latching mode).
After removal of the over voltage condition the DC/DC
converter will resume to normal operation automatically.
The maximum required sink current is less than 1 mA. When
the RC pin is left open, the voltage generated on the RC pin is
5-10 V. The second option is “positive logic” remote control,
which can be ordered by adding the suffix “P” to the end of the
part number. The DC/DC converter will turn on when the input
voltage is applied with the RC pin open. Turn off is achieved
by connecting the RC pin to the - In. To ensure safe turn off
the voltage difference between RC pin and the - In pin shall be
less than 1 V. The DC/DC converter will restart automatically
when this connection is opened.
Over Current Protection (OCP)
The DC/DC converters include current limiting circuitry for
protection at continuous overload.
The output voltage will decrease towards zero for output
currents in excess of max output current (max IO). The DC/DC
converter will resume normal operation after removal of the
overload. The load distribution should be designed for the
maximum output short circuit current specified.
Input and Output Impedance
The impedance of both the input source and the load will
interact with the impedance of the DC/DC converter. It is
important that the input source has low characteristic
impedance. Minimum recommended external input
capacitance is 220 µF. The performance in some applications
can be enhanced by addition of external capacitance as
described under External Decoupling Capacitors.
External Decoupling Capacitors
When powering loads with significant dynamic current
requirements, the voltage regulation at the point of load can
be improved by addition of decoupling capacitors at the load.
The most effective technique is to locate low ESR ceramic and
electrolytic capacitors as close to the load as possible, using
several parallel capacitors to lower the effective ESR. The
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