Ericsson RBS 2106 Hardware Reference Manual page 316

+24 V DC to -48 V DC/DC Converter for RBS 2106
4 Function Description
Figure 1 Block diagram
The unit is a switched converter, that converts +24 V DC battery voltage to
regulated –48 V DC. The converter can be connected in parallel with other
converters to operate continuously in current limitation mode.
The exact value of the output voltage can be adjusted using the potentiometer
("U out adj") on the front panel. For adjustment range, see Section 5.1 Signal
and Power Interfaces.
The current limitation is set to 100 – 115% of the rated current (4.0 A), above
which the output voltage drops. The output current increases when the voltage
drops, enabling the converter to be loaded with other DC/DC converters with
an input power limited to approximately 150 W.
The overvoltage protector shuts down the switching when the output voltage
reaches –58 V. The output is restored by switching the converter ON/OFF
switch to OFF and then after 15 seconds to ON again.
The ON/OFF switch is also a resettable automatic fuse for the input current.
The undervoltage protector monitors the input voltage and blocks the
converter at an input voltage of 18 – 21 V. The exact level is set by a
potentiometer ("Stop adjust") on the front of the unit. The converter is restored
automatically when the input voltage rises 5 V above the stop level.
The converter can be stopped remotely by connecting a +5 V signal to the pin
"Stop". Normally this pin is left unconnected.
A green indicator on the front indicates that an input voltage, which has
reached starting level, is present in the conversion stage.
4 (8)
Input +24 V DC
Input ALARM
Input Stop
U in test
Start test
Stop test
=
=
Control Circuit
DC/DC Converter
Output -48 V DC
Output -48 V DC
Output FAIL
U out test
I out test
P009809A
EN/LZT 720 0301 R1A