Sorensen SGI Series Operation
M550221-01 Rev U 3-43
3.10 Remote Current Programming
Remote current programming is summed with the front panel or digital setting;
see Section 3.9. Remote current programming is used for applications that
require the output current be programmed (controlled) from a remote
instrument. An external resistance or external voltage source may be used as
a programming device. When using remote current programming, a shielded,
twisted-pair cable is recommended to prevent noise interference to
programming signals.
3.10.1 Remote Current Programming by Resistance
The resistance-programming coefficient for output current is
(100% rated output current) / 5 kΩ, with input at Pin J1-22 (IP RES) and return
to Pin J1-23 (IP RTN). An internal current source, factory-set at 1 mA, from
Pin J1-22 (IP RES) is utilized to drive the resistance. This produces a transfer
function for output current, as follows:
Iout = R * (100% rated output current) / 5 kΩ), with R in ohms.
If multiple switches or relays are used to select resistors to program different
current levels, make-before-break contacts are recommended.
Note:
If an external resistance is used for remote programming, the current
programming return Pin J1-23 (IP RTN), must be connected directly to, or
within ±3 V, of the circuit common, Pins J1-6 and J1-24. See Figure 3-14 for
connection requirements.
Figure 3-14. Remote Current Programming Using Resistance
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