Keysight E3632A - Figure 6-9 Speed of Response - Programming down

Tutorial 6
Remote Programming
E3632A User’s Guide 165
When this exponential rise reaches the newly programmed
voltage level, the constant voltage amplifier resumes its
normal regulating action and holds the output constant.
Thus, the rise time can be determined approximately using
the formula shown in
Figure 6- 8.
If no load resistor is attached to the power supply output
terminal, then the output voltage will rise linearly at a rate
of C
O
/I
L
when programmed upward, and 
T
R
= C
O
(E
2
– E
1
)/I
L
, the shortest possible up- programming
time.
Figure 6-9 Speed of response — programming down
Figure 6- 9 shows that when the power supply is
programmed down, the regulator senses that the output
voltage is higher than desired and turns off the series
transistors entirely. Since the control circuit can in no way
cause the series regulator transistors to conduct backwards,
the output capacitor can only be discharged through the load
resistor and internal current source (I
S
).
The output voltage decays linearly with slope of I
S
/C
O
with
no load and stops falling when it reaches the new output
voltage which has been demanded. If full load is connected,
the output voltage will fall exponentially faster.