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3-39
Figure 3-4 illustrates the method by which a power
supply's constant voltage output can be programmed using
an external voltage with a voltage gain dependent upon the
ratio of Rp to RR. Note that this method is no different
from the circuit normally used for constant voltage control
of the output except that an external reference (the pro¬
gramming voltage source) has been substituted for the
internal reference. On most supplies, external terminals
are available so that the connections shown in Figure 3-4
can be accomplished without any internal wiring changes.
In all HP remotely programmable power supplies, the
summing point S is made available, and the configuration
of Figure 3-4 can always be accomplished using the external
programming voltage source Ep and external precision wire-
wound resistors Rp and Rp. (Rp should not exceed 10k;)
As indicated by the equation in Figure 3-4, Rp can be
selected so that the resulting voltage gain is either less or
greater than unity. It is possible to use the front panel
control on the supply as the voltage gain control Rp.
Figure 3-4. Voltage Programming with Variable Voltage Gain
3-40
Constant Voltage. Figure 3-5 illustrates the con¬
nections required for the 59501B to program the constant
voltage (CV) output of a typical HP power supply. Note
the similarities between Figures 3-4 and 3-5. The 59501B
includes RR (R76), Rp (COARSE and FINE POWER
SUPPLY FULL SCALE ADJUST), and Ep { 59501B.output
between terminals A1 and A2). The extra resistor (R77)
between terminals A5 and A6 is used only when program¬
ming power supplies above 300 volts.
3-41
As shown in Figure 3-5, the supply's internal
reference voltage (+VREp) and VOLTAGE control are
disconnected (dotted lines) and are replaced with the
59501 B's output voltage and POWER SUPPLY FULL
SCALE ADJUST. Note that in the unipolar mode, 59501B
output terminal A1 is negative with respect to A2. This
polarity must be complied with when making connections.
The connections shown in Figure 3-5 are typical for most
supplies.
3-42
Constant Current. Figure 3-6 illustrates the
connections required for the 59501B to program the out¬
put current of a typical HP power supply. Programming
constant current consists of replacing the internal reference
with the output voltage from the 59501B and replacing
the internal CURRENT control with the POWER SUPPLY
FULL SCALE ADJUST controls on the 59501B . With
these connections, the voltage developed across POWER
SUPPLY FULL SCALE ADJUST (Rp) becomes the reference
against which the voltage drop across the output current
monitoring resistor (Ry) is compared. The relationship
between Ep and the supply's output current depends upon
the resistance ratio Rp/Rpand on the constant current pro¬
gramming coefficient (Kp) of the particular supply. The
relationship between input voltage and output current is,
IqUT ~ (Ep x
Ep ) " (Kp x RR)
595oib_
j
r
(zero adjust!
I
!
9
Figure 3-5. Typical Connections for CV Programming
3-5
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