Calibration Sequence; Digitalcalibration; Input Offset Voltage Adjustment; Capacitance Offset Compensation - Keithley 595 Instruction Manual

MAINTENANCE
HP-85 Frog
amming Example--The simple program below
2. The top cover will have to be removed to make internal
will aLlow you to send the desired calibration command
adustments. To help maintain a proper internal tempem-
string to the Model 595. The program assumes that the &-
&re level, keep the top cover on the instrument when
strument primary address is at its default value of 28.
not making internal adjostsments.
PROGRhM
COMMENTS
lE1 REMOTE
728
Send remote enable.
20 DISF~~CALIfiRkTIO~4
Promptforcommand.
COMMAt4D' 5
33 It4FUTA5: Input
command string
8.5.8 Digital Calibration
~If o'igital calibration is to be performed from the front panel,
the instrmnent~will have to be placed in the calibration pro-
gram. J.Wigital calibration is going to be done over the
,IEEE-4%3 bus, the instrument enters the calibration mode
automatically when the calibration command (A) is sent.
40 OIJTFIJT 728iAS
frsm keyboard.
Send command string to
595.
Repeat:
To run the program, press the HP-85 RUN key. At the com-
mand prompt, type in the desired calibration command
and press &urn. For example, to perform permanent
calibration constant storage, type in Jl9X and press return.
To stop the program, press the HP-85 PAUSE key.~
8.5.7 Calibration Sequence
Model 595 Calibration must be performed in the order
given in the following paragraphs, with the exception of
voltage source calibration, which can be done at any time.
The basic sequence is:
1. Input~offset voltage adjustment (paragraph 8.5.9)
2. Zero Hop Compensation (paragraph 8.510)
3. Input current adjustment (paragraph 8.5.11)
4. Capacitance offset compensation (paragraph 8.5.1.2)
5. Voltage source calibration (paragraph 8.5.13)
6. Current calibration (paragraph 8.5.14)
7. IC analog output adjustment (paragraph 8.5.15)
8. Q/t calibration (paragraph 8.5.16)
9. Capacitatice &ibration (paragraph 8.5.17)
In addition to the above sequence, the ranges for each func-
tion must be calibrated in the order given.
Notes:
1. Never calibrate a range using a suppress~ value taken on
a different range.
For front panel digital call&ration, select the calibration pm
gam as follows:
1. Turn off the Model 595.
2. While holding in the program MENU button, power up
the Model 595.
3. Aft&r the display blanks for approximately one second,
let go of ~the MENU button. The calibration program is
now included in the program menu and will remain
there as long as the instrument~-remains on.
4. Repeatedly press the MENU button until the following
message is displayed:
CAL
5. With the "CAL!' message dispiayed, release the MENU
button. The instrument is now in the calibration program
as indicated by the displayed exponent decimal points.
8.5.9 Input Offset J.k&age Adjustment
Use the foliowing procedure to null out any small offset
voltage. Input offset adjustment is particularly critical ifin-
put voltage burden is a consideration since :any offset will
~:mcrease the voltage burden, as seen by the input signal.
NOTE
If the following adjustment cannot be made, the
input stage will need to be balanced. Usually,
balancing only needs to be done if the input FET
or an associated comoonent is reolaced. To balance
the input stage, peiform the phcedure in para-
graph 8.9.