KEPCO BHK-MG 200W (Full Rack) Series - Manual (Page 81)

BHK-MG (OPR) 022014
3-37
3.6.2.1 VOLTAGE MODE
With the power supply in voltage mode (see Figure 3-9) and the digitally programmed output
voltage at zero, varying the external resistor from 0 to 10K causes the output voltage of the
power supply to vary linearly from 0 to Eomax with a slope of (0.0001 x Eomax) volts per ohm.
The following equation gives the output voltage as determined by external resistance R
EXT
.
Eo = (–1) (10V) x (R
EXT
/10K) x (–1) (10K/10K) x (–1) (R/10K)
= (–1) (0.1 x R) x R
EXT
= –0.1R x R
EXT
(V d-c)
where
R
EXT
= External resistance (K-ohms), variable from 0 to 10K ohms. This resistance can take
the form of a rheostat, a fixed resistor, or a group of resistors which are step-switched
by mechanical, electrical or electronic means (step-switching must be “make before
break”). Use only high quality resistor(s) having a temperature coefficient of 20 parts
per million or better and a wattage rating of 0.5W minimum.
R = Internal feedback resistance equal to correction resistance (K-ohms), determined by
Model (see Table 3-10).
NOTE: Output voltage is referenced to +OUT and output current is negative leaving +OUT ter-
minal. This convention applies to voltage and current programming calculations of
PAR. 3.6.
3.6.2.2 CURRENT MODE
With the power supply in current mode (see Figure 3-10) and the digitally programmed output
voltage at zero, varying the external resistor from 0 to 10K causes the output current of the
power supply to vary linearly from 0 to Iomax with a slope of (0.0001 x Iomax) mA per ohm. The
following equation gives the output current as determined by external resistance R
EXT
.
Io = [ (–1) (10V) x (R
EXT
/10K) x (–1) (1K/10K) x (–1) (1K/1K) ]/Rs
= (–1) (0.1/ Rs) x R
EXT
= (–0.1/Rs) x R
EXT
(mA d-c)
where
Rs = Internal shunt resistance (K-ohms), determined by Model (see Table 3-10).
(See above for definition of R
EXT
.)