Keithley 6487 Reference Manual

8-2 Limit Tests and Digital I/O Model 6487 Reference Manual
Limit testing
As shown in Figure 8-1, there are two limit tests that can be performed on a DUT. Limit 1
is used as the wide pass band and Limit 2 is used as the narrow pass band. It is up to the
user to specify limits that conform to this pass band relationship.
Figure 8-1
Limit tests
Figure 8-2 shows an example where the HI and LO limits for Limit 1 are ±2mA and the HI
and LO limits for Limit 2 are ±1mA. A 0mA reading passes both Limit 1 and Limit 2 tests.
A +1.5mA reading passes Limit 1 but fails Limit 2. A +2.5mA reading fails both Limit 1
and Limit 2.
Figure 8-2
Limit tests example
LO
LO
Limit
Limit
HI
HI
Limit
Limit
Limit 1 Test
(Wide Pass Band)
Limit 2 Test
(Narrow Pass Band)
Fail
Fail Fail
FailPass
Pass
-2mA
-1mA
LO Limit
LO Limit
+2mA
+1mA
HI Limit
HI Limit
Limit 1 Test
(Wide Pass Band)
Limit 2 Test
(Narrow Pass Band)
Fail
Fail Fail
FailPass
Pass

Keithley 6487 Specifications

General

Type	Picoammeter/Voltage Source
Current Measurement Range	20 fA to 20 mA
Interfaces	GPIB, RS-232
Voltage Burden	< 200 µV
Input Impedance	>10^14 Ω
Power	100 V / 120 V / 220 V / 240 V
Basic Current Measurement Accuracy	0.4%