will indicate parameters have been entered). The nominal
adjustment range is *6% (+12% in external feedback).
However, it is important to note that such calibration will be
only temporary as these parameters will be lost when the
power is turned off. Under these conditions, the instrument
will revert to calibration constants previously stored in
NVRAM the next time it is turned on. Note that the IEEE-488
DCL and SDC commands will also cancel temporary calibra-
tion constants.
As an example of this procedure, let us assume that you wish
to temporarily calibrate the 2mA range-a range that is not
part of the normal calibration sequence. The following basic
procedure could be used to calibrate this range.
1. Select the amps mode and place the instrument on the 2mA
range.
2. Zero correct the instrument by enabling zero check and
then zero correct in that order.
3. Connect a suitable calibration signal to the instrument.
Typically, calibration is done at 95% of full range, or
1.90001n.4 in this case.
4. Disable zero check and enter the front panel calibration
program, as described in paragraph 7.4.4. The instrument
will then display a reading that reflects its present calibra-
tion point for the selected range. The exact point can be set
by using the voltage source adjust buttons to set the dis-
played value to exactly 1.9ooOmA.
5. After all points have been calibrated, exit the program by
pressing SHIFT then SELECT.
6. If bus calibration is desired instead, send the calibration
signal Over the bus. In this case the command would be:
A1.9E-3X.
7. Any non-standard calibration points will be only tem-
porary, as stated earlier.
7.5 SPECIAL HANDLING OF STATIC-
SENSITIVE DEVICES
CMOS devices operate at very high impedance levels for low
power consumption. As a result, any static charge that builds
up on your person or clothing may be sufficient to destroy
these devices, if they are not handled properly. Table 7-7 lists
static-sensitive devices used in the Model 617. When handling
these devices, use the precautions below to avoid damaging
them.
1. The ICs listed in the table should be transported and hand-
led only in containers specially designed to prevent static
build-up. Typically, these parts will be received in anti-
static containers of plastic or foam. Keep these devices in
their original containers until ready for installation.
2. Remove the devices from their protective containers only
at a properly grounded work station. Also ground yourself
with a suitable wrist strap.
3. Handle the devices only by the body; do not touch the
pins.
4. Any printed circuit board into which the device is to be in-
serted must also be arounded to the bench or table.
5. Use only anti-static type solder suckers.
6. Use only grounded tip soldering irons.
7. Once the device is installed on the PC board, it is normally
adequately protected, and normal handling can resume.
Table 7-7. Static Sensitive Devices
Circuit Keithley
Designation
Part Number
a103
TF-139
0104
0105
Q106
a107
Q108
Q113
u102
u103
u105
U106
u107
U108
u109
UllO
Ulll
u112
u113
U116
u117
U118
U126
U127
U128
u129
u131
U132
u133
u135
U136
U138
u139
u140
u141
U142
u145
U203
U206
Q302
0308
a310
u301
U302
u303
K-354
TG-166
TG-128
617-600
TG-139
TG-128
TG-177
E-163
IC-407
K-103
LSI-56
LSI-58
IC-338
LSI-60
IC-338
IC-351
K-143
LSI-49
IC-338
c-412
IC341
c-337
IC-407
K-412
IC-316
K-251
IC-324
IC-251
c-341
K-283
IWO8
c-347
IC-251
IC-247
IC-410
K-283
IC-398
IC-277
TG-128
617-602
TG-177
IC-251
K-354
7-11
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