Operating Information
Remote Sense
Input Voltage
The input voltage range 36…75Vdc meets the requirements of the
European Telecom Standard ETS 300 132-2 for normal input voltage
range in –48V and –60V DC systems, -40ꢀ5…-57ꢀ0V and –50ꢀ0…-
72V respectivelyꢀ At input voltages exceeding 75V, the power loss
will be higher than at normal input voltage and TPcb must be limited
to absolute max +110°Cꢀ The absolute maximum continuous input
All PKB 4000 Series DC/DC converters have remote sense that
can be used to compensate for moderate amounts of resistance in
the distribution system and allow for voltage regulation at the load
or other selected pointꢀ The remote sense lines will carry very little
current and do not need a large cross sectional areaꢀ However, the
sense lines on the PCB should be located close to a ground trace
or ground planeꢀ In a discrete wiring situation, the use of twisted
pair wires or other technique to reduce noise susceptibility is highly
recommendedꢀ The remote sense circuitry will compensate for up to
10% voltage drop between the sense voltage and the voltage at the
output pinsꢀ The output voltage and the remote sense voltage offset
must be less than the minimum over voltage trip pointꢀ If the remote
sense is not needed the –Sense should be connected to –Out and
+Sense should be connected to +Outꢀ
voltage is 80Vdcꢀ
Turn-Off Input Voltage
The PKB 4000 Series DC/DC converters monitor the input voltage
and will turn on and turn off at predetermined levelsꢀ The minimum
hysteresis between turn on and turn off input voltage is 1V where
the turn on input voltage is the highestꢀ
Remote Control (RC)
Output Voltage Adjust (Vadj
)
All PKB 4000 Series DC/DC converters have an Output Voltage
adjust pin (Vadj)ꢀ This pin can be used to adjust the output voltage
above or below Output voltage initial settingꢀ When increasing the
output voltage, the voltage at the output pins (including any remote
sense offset) must be kept below the overvoltage trip point, to
prevent the converter from shut downꢀ Also note that at increased
output voltages the maximum power rating of the converter remains
the same, and the output current capability will decrease corre-
spondinglyꢀ To decrease the output voltage the resistor should be
connected between Vadj pin and –Sense pinꢀ To increase the voltage
the resistor should be connected between Vadj pin and +Sense pinꢀ
The resistor value of the Output voltage adjust function is according
to information given under the output sectionꢀ
The PKB 4000 Series DC/DC converters
have a remote control function referenced
to the primary side (- In), with negative
and positive logic options availableꢀ The
+In
RC
RC function allows the converter to be
turned on/off by an external device like a
semiconductor or mechanical switchꢀ The
RC pin has an internal pull up resistor to
+ Inꢀ The needed maximum sink current
is 1mAꢀ When the RC pin is left open,
-In
Circuit configuration
for RC function
the voltage generated on the RC pin is 12 - 15 Vꢀ The maximum
allowable leakage current of the switch is 20 µAꢀ
The standard converter is provided with “negative logic” remote
control and the converter will be off until the RC pin is connected
to the - Inꢀ To turn on the converter the voltage between RC pin
and - In should be less than 1Vꢀ To turn off the converter the RC
pin should be left open, or connected to a voltage higher than 13
V referenced to - Inꢀ In situations where it is desired to have the
converter to power up automatically without the need for control
signals or a switch, the RC pin can be wired directly to - Inꢀ
+Out
+Out
+Sense
+Sense
R
adj
Load
Load
V
V
adj
adj
The second option is “positive logic” remote control, which can
be ordered by adding the suffix “P” to the end of the part numberꢀ
The converter will turn on when the input voltage is applied with
the RC pin openꢀ Turn off is achieved by connecting the RC pin to
the - Inꢀ To ensure safe turn off the voltage difference between RC
pin and the - In pin shall be less than 1Vꢀ The converter will restart
automatically when this connection is openedꢀ
R
adj
-Sense
-Sense
-Out
-Out
Decrease
Increase
Circuit configuration for output voltage adjust
EN/LZT 146 033 R9A ©Ericsson Power Modules, March 2007
38
PKB 4000 Datasheet
ERICSSON [ ERICSSON ]
