Service Information; Principles Of Operation - Agilent Technologies E3630A Manual De Funcionamiento Y Servicio

PRINCIPLES OF OPERATION

(Block Diagram Overview)
This section presents the principles of operation of the
E3630A Triple Output Power Supply. Throughout this discus-
sion, refer to both the block diagram of Figure A-1 and the
schematic diagrams at the rear of the manual.
The two primary windings of the power transformer are con-
nected in one of three different ways by setting the two slide
switches mounted on the circuit board. These switches select
one of the nominal ac input voltages for which the supply is
designed: 100 V, 115 V, or 230 V.
The transformer secondaries, together with rectifiers and
capacitor filters, provide raw dc for the three output regulator
circuits and for another regulator that provides reference and
bias voltages to the output regulators.

SERVICE INFORMATION

Figure A-1. Block Diagram
A-1
By comparing its output to a high-stability reference, the 0 to
+6-volt regulator holds its output voltage at the value deter-
mined by a front panel control. Any error in the actual output
as compared to the desired output is amplified by an opera-
tional amplifier and applied as feedback to control the con-
duction of a series regulator transistor. As a result, the
voltage across the series transistor varies so as to hold the
output voltage constant at the desired level. The high gain of
the voltage comparison amplifier and the stability of the refer-
ence voltage ensure that input voltage or load current varia-
tions have little effect on the output voltage.
The 0 to +6-volt output is protected by a current foldback lim-
iter to minimize dissipation in the series regulator transistor
during overloads. In a current foldback circuit, the current limit
depends on the output terminal voltage. The current limit
ranges from 2.75 A ± 5% at 6 volts to 1 A ± 15% with the out-
put shorted. The operating region of the +6-volt regulator out-