SORENSEN DCS SERIES MANUAL THEORY OF OPERATION
3-7
Remote Programming of the Output Voltage
During remote programming of the output voltage with an external voltage source (0-5V or 0-10V) the local
operation jumpers connecting J3 pins 8 to 9 and 20 to 21 are removed and the external source is connected between
pins 9 (positive) and 12 (negative) of connector J3. The input signal at J3 pin 9 is buffered via U14-2 to provide
noise immunity. When using a 0-5V source the reference at pin 2 of U5 (voltage control op amp) is provided
directly by the external source. When using a 0-10V source switch SW1-3 is closed to provide the necessary
voltage divider to scale the reference voltage to 0-5V.
For remote programming with an external 5k resistance the jumpers connecting J3 pins 8 to 9 and 20 to 21 are
removed, pins 9 and 21 are connected to the counterclockwise end of the external 5k ohm potentiometer and the
tap and clockwise end are connected to pin 12. The internal 1mA current source at pin 21 develops a 0-5V
potential across the potentiometer, depending on the potentiometer setting, which is fed to pin 2 of U5.
During remote programming of the output voltage with an external 0-1mA current source the jumper connecting
J3 pins 20 and 21 is removed, the front panel voltage control is set fully clockwise and the external current source
is connected between pins 8 (positive) and 12 (return). Varying the current source from 0-1mA causes 0-5V to
develop at the reference pin of the voltage control circuit.
The front panel remote programming indicator is controlled by op amp U8-4. Resistors R55 and R56 form a
voltage divider with the 6.2V reference which develops a nominal 0.3V at pin 12 (the non-inverting input) of the
op amp. During local operation current flow through diode CR15 and the front panel voltage control provides a
higher voltage at pin 13 (the inverting input) keeping U8-4 output low. During remote programming there is no
current flow through diode CR15 and the output of U8-4 goes high illuminating the remote programming indicator
through diode CR4, resistor R13 and pin 13 of connector J1. The high signal is also provided at pin 4 of connector
J3 for remote monitoring purposes.
Remote Programming of the Output Current Limit
During remote programming of the output current limit with an external voltage source the local operation jumpers
connecting J3 pins 10 to 11 and 22 to 23 are removed and the external source (0-100mV, 0-5V or 0-10V) is
connected between pins 10 (positive) and 12 (negative). The input signal at J3 pin 10 is buffered via U14-1 to
provide noise immunity. When using a 0-5V source the reference at pin 2 of U4-1 (current control op amp) is
provided by the external source and divided down to a 0-2V reference by R20 and R146. Use of a 0-10V source
requires that switch SW1-1 be closed to add R5 to the voltage divider to limit the control circuit reference voltage
to 0-2V. For 0-100mV, programming switch SW1-1 is opened and switch SW1-2 is closed, changing U14-1 from
a voltage follower to an amplifier by virtue of feedback resistor R150 and voltage divider resistor R50.
For remote programming with an external 5k resistance the jumpers connecting J3 pins 10 to 11 and 22 to 23 are
removed, pins 10 and 22 are connected to the counterclockwise end of the external 5k ohm potentiometer and the
tap and clockwise end are connected to pin 12. The internal 1mA current source at pin 22 develops a 0-5V
potential across the potentiometer, depending on the potentiometer setting, which is fed to pin 6 of U4-2.
During remote programming of the output voltage with an external 0-1mA current source the jumper connecting
J3 pins 22 and 23 is removed, the front panel voltage control is set fully clockwise and the external current source
is connected between pins 11 (positive) and 12 (return). Varying the current source from 0-1mA causes 0-5V to
develop at the reference pin of the current control circuit.
The front panel remote programming indicator is controlled by op amp U8-1 during remote current limit
programming. Operation is the same as that described above in the remote voltage programming section except
that diode CR15 is replaced by diode CR16.
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