Capacitancemodifiers - Keithley 595 Instruction Manual

IEEE-488
PROGRANMING
4.9.16
Capacitance Modifiers (a)
Purpose
Format
Parameters
Description
Default
Reference
Example
Use with the instrument in the capacitance function (FO) to display the capacitance
reading or the Q/t current reading. Also use to automatically correct the capacitance
readings for leakage current.
Qn
n = 0 Capacitance displayed, capacitance not corrected
n = 1 Q/t displayed, capacitance not corrected
n = 2 Capacitance displayed, capacitance corrected
n = 3 Q/t displayed, capacitance corrected
Display--With the instrument in the capacitance fun&ion (FO), capacitance readings
will be displayed when QO or Q2 is sent over the bus. When Ql or Q3 is sent, Q/t
current readings will be displayed.
Correction--When the voltage step occurs, the device under test will change to its
new equilibrium state. Once equilibrium has been reached, only DC leakage cur-
rents will flow. Q/t represents the current measured during the last 'Is of the delay
time (or 44msec, whichever is greater). The Q2 and Q3 commands are used to cor-
rect the capacitance reading for DC leakage current errors.
Upon power up or after a DCL or SDC command is received, the instrument will
be in QO.
Equivalent~front panel control of the display (capacitance or Q/t) is accomplished
with SHIFT then CAl?ACITANCE~(Q/T) (see paragraph 3.32). Correction is ac-
complished through a front panel program (see paragraph 3.46).
Place the instrument in the capacitance function and enter the following statements
into the computer to display the uncorrected Q/t v&e (Ql):
REMOTE 728
When END LINE is pressed the second time, the Qkvalue will be displayed. After
FND LINE is pressed the third time, the unit-kill return to uncorrected capacitance
display.
NOTES:
1. Using capacitance correction with a non-equjliirium measurement will yield
incorrect results. See paragraph 3.4.6 for details.
2. Sending the Q command while the instrument is in the current function (Fl) will
result in a conflict error (see paragraph 4.7.3).
3. The C and N commands apply only to the capacitance reading, even while display-
ing Q/t.
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