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Chapter 3
External Control
If you use a shielded cable, connect the shield to the negative output terminal. Refer to
When Controlling the Output with an External Voltage (Vext)
if the shield needs to be connected
to the Vext side. Use pins 21 and 23 of the J1 connector.
Control Using an External Resistance (Rext)
An external variable resistor (Rext) can be used along with the Reference Voltage Output (pin
20 on the J1 connector) to externally control the output current of the power supply. You can use
this method to set the output current (Io) to a value from 0% to 105% of the rated output current
(Irtg).
To use an external resistance (Rext) to control the output current, set CONFIG setting CF05 to
ON to enable control of the output current using an external resistor.
The output current (Io) varies in the range of 0 to the rated output current (Irtg) when the external
voltage (Vext) is changed in the range of 0 to 5 V (CF07: Lo) or in the range of 0 to 10 V (CF07: Hi).
External Resistance (Rext) Connection
For Rext, use a resistor that is rated at approximately 10 k
Ω
, 1/2 W or greater, that has a low
temperature coefficient, and that will change little over time. Examples of such resistors are
metal film or wire wound resistors.
To reduce the noise on the output, connect a 2-core shielded wire or a twisted-pair wire, and keep
the wire as short as possible. If the wiring is long, it becomes easy for noise to influence the
operation of the RMX programmable power supply. Even if you use wires that are designed to
suppress noise, the RMX programmable power supply may not operate properly.
Figure 3-15.
CC Rext Connection.
If you use a shielded cable, connect the shield to the negative output terminal. Use pins 20, 21,
and 23 of the J1 connector.
External voltage (Vext)
0 to 5 V (CF07: Lo)
External voltage (Vext)
0 to 10 V (CF07: Hi)
Io = Irtg × Vext/5 (in A)
Vext = 5 × Io/Irtg (in A)
Io = Irtg × Vext/10 (in A)
Vext = 10 × Io/Irtg (in A)
2-core shielded wire or
twisted-pair wire
Output terminals
J1
20
21
2
3
RMX
R
ext
V
ext
Wiper
