User Manual

Table Of Contents
9 Way Channelised UHF Cell Enhancer
Maintenance Handbook
H/book Number:-50-025301HBKM
Issue No:-
1
Date:-04/07/2003
Page:-
41 of 69
5.2.8 Single DC/DC Converter (13-001702)
5.2.8.1 Description
This unit it is used to derive a fixed voltage power supply rail from some higher voltage.
Typically, it is used to derive 5V, 8V, 12V or 15V from a 24V input. This particular
regulator is dedicated to supply 12.8V DC.
The circuit is based upon an LM317 variable voltage regulator, which is capable of
supplying a maximum of 1.5A output current. Note that at full output current the
dissipation of the device must remain in limits, bearing in mind the voltage which is
being dropped across it. The maximum allowable dissipation will also depend on the
efficiency of the heatsink on which the device is mounted.
The output voltage of the unit is programmed by the resistive divider which is fitted
between the output terminal, the reference terminal and ground. R1 is the reference
programming resistor and is fixed in all versions. R2 is fitted on 12V versions while R3,
(which is in parallel with R2) is fitted on 8V and 5V versions.
5.2.8.2 Technical Specification
PARAMETER SPECIFICATION
Operating Voltage: 21 – 27V DC
Output Voltages: 12.4V (typical)
Output Current: 1.0A (maximum per o/p)
Connections: Screw Terminal Block
operational:
-10ΒC to +55ΒC
Temperature
range:
storage:
-40ΒC to +70ΒC
PCB Size: 47 x 30mm