Keithley 2182, Руководство пользователя, Страница: 148 / 339

Figure 8-3
Limits to sort 10 Ω resistors (1%, 5%, and >5%)
Front panel operation — For front panel operation, the INSIDE beeper mode must be used.
A normal pitch beep and the message “IN” indicates that the resistor is within the 1% tolerance
limit (see
Figure 8-3 ). This 1% resistor belongs in Bin 1. A low pitch beep and the “HI” or “LO”
message indicates that the resistor is >1% tolerance but <5% tolerance. This 5% resistor belongs
in Bin 2. For resistors >5%, no beep will sound. Place these resistors in Bin 3.
Remote operation — For remote operation, make sure both Limit 1 and Limit 2 are enabled.
The following table evaluates the three possible pass/fail combinations for this application.
Keep in mind that a fail condition must be reset before testing the next resistor. Fail can be
reset manually or automatically (see CLEar command in Table 8-1 ).
Nulling thermal EMFs — To maximize handling speed, quick-disconnect test clips are
typically used for the resistor connections. Unfortunately, these connections may contribute
enough thermal EMFs to corrupt the measurement. The Relative feature of the Model 2182 can
be used to null out this offset as follows:
1. Connect the test circuit shown in Figure 8-1 , but leave the current source disconnected.
2. Using the lowest possible range (or autorange) measure the offset voltage.
3. Press REL to zero the display of the Model 2182.
4. Connect the current source and test the resistors.
NOTE As long as all the resistor leads in the batch are made of the same metal, the Rel value
obtained for the first resistor should be satisfactory for each subsequent resistor.
Limit 1
Result Limit 2
Result Resistor
Tolerance Bin
Assignment
Pass Pass 1% 1
Fail Pass 5% 2
Fail Fail >5% 3
-9.5mV
LO2
-9.9mV
LO1
+10.1mV
HI1
+10.5mV
HI2
LO IN HI
Limit 1 (1%)
Limit 2 (5%)
0
No Beep
Beep
(low pitch)
Beep
(normal pitch)
Beep
(low pitch) No Beep
Beeper Mode: INSIDE
8-8 Limits