Instruction Manual

3-46 BHK-MG (OPR) 022014
3.6.4.1 VOLTAGE MODE
With the power supply in voltage mode (see Figure 3-15) and the digitally programmed output
voltage at zero, varying the high impedance voltage source from 0 to –1V causes the output
voltage of the power supply to vary linearly from 0 to Eomax with a slope of (Eomax) volts per
volt. The following equations give the output voltage as determined by a high impedance volt-
age source V
EXT
.
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Eo = (V
EXT
) x (11.1K/1.1K) x (–1) (10K/10K) x (–1) (R/10K)
= –(R) x |V
EXT
| (V d-c)
where
R = Internal feedback resistance equal to correction resistance (K-ohms), determined by
Model (see Table 3-10).
V
EXT
= External low impedance voltage source. This source can be either a d-c source deliver-
ing a negative output voltage, or a function generator with an internal negative bias. If
the bias is not available from the function generator, use the digital programming fea-
ture of the BHK-MG to provide proper bias to avoid clipping the waveform at the output
of the power supply.
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Eo = –(R x |V
EXT
|) – Eout
DP
(V d-c)
where
Eout
DP
= Output voltage programmed digitally (from either local keypad or remote GPIB bus)
(See above for definitions of R and V
EXT
.)
3.6.4.2 CURRENT MODE
With the power supply in current mode (see Figure 3-16) and the digitally programmed output
voltage at zero, varying the high impedance voltage source from 0 to –1V causes the output cur-
rent of the power supply to vary linearly from 0 to Iomax with a slope of (Iomax) mA per volt. The
following equations give the output current as determined by the low impedance voltage source
V
EXT
.
ANALOG PROGRAMMING, DIGITAL PROGRAMMING = 0:
Io = [ (V
EXT
) x (11.1K/1.1K) x (–1 ) (1K/10K) x (–1) (1K/1K) ]/Rs
= –(1/Rs) x |V
EXT
| (mA d-c)
where
Rs =Internal shunt resistance (kOhms), determined by Model (see Table 3-10).
(See above for definition of V
EXT
.)
ANALOG PROGRAMMING COMBINED WITH DIGITAL PROGRAMMING:
Io = –(1/Rs) x |V
EXT
| – Iout
DP
(mA d-c)
where