Figure 2-7 Dc In-Circuit Current Measurements; Dci And Aci Auto Resolution; Table - Keithley 2002 User Manual

Front Panel Operation

Table 2-15

DCI and ACI auto resolution

Measurement
function and type Integration time
DC current 0.01 to <0.02 PLC
0.02 to <0.20 PLC
0.20 to <2.00 PLC
2.00 to 50 PLC
DC in-circuit current Not used
RMS, average 0.01 to <0.02 PLC
0.02 to <10.00 PLC
10.00 to 50 PLC
Notes:
1. For normal DC current, if the resolution is AUTO and the integration
time is SET-BY-RSLN, the resolution will be 6.5 digits and the integra-
tion time 1.0 PLC.
2. For DC in-circuit current, the integration time setting is ignored.
3. For AC current, if the resolution is AUTO and the integration time is
SET-BY-RSLN, the resolution will be 5.5 digits and the integration
time 1.0 PLC.
IN-CIRCUIT: In-circuit current is a calculation based on a
4-wire resistance measurement and a voltage measurement.
It is similar to an offset-compensated ohms measurement.
+00.207 ADC ICkt
Trace resistance: 1.0000
PREV DCV ACV DCI
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REL TRIG STORE RECALL
POWER
INFO LOCAL CHAN
Caution : Maximum Input = +200mV on
(I + I
-
IN CKT
I = 10mA.
SOURCE
Figure 2-7
DC in-circuit current measurements
2-26
Resolution
4.5d
5.5d
6.5d
7.5d
5.5d
4.5d
5.5d
6.5d
Model 2002
SENSE
350V
PEAK
2002 MULTIMETER
INPUTS
ACI 2 4
FREQ TEMP
F
RANGE
AUTO
FRONT/REAR
FILTER MATH
RANGE
SCAN CONFIG MENU EXIT ENTER
) • R , where
SOURCE TRACE
The current in a low resistance conductor (e.g., a printed
circuit trace) can be measured without breaking the current
path. The Model 2002 can do this with a pair of Kelvin test
probes across the conductor. See Figure 2-7. The method
follows:
1. Using one set of the Kelvin probe tips, the instrument
sources a known current (I
and simultaneously measures the resulting voltage
(V
MEAS1
V
or
2. The instrument then measures the voltage (V
across the conductor without sourcing an additional
current:
or
INPUT
4 WIRE
HI
1100V
PEAK
LO
500V
PEAK
Circuit
R
Under Test
2A 250V
AMPS
CAL
) through the conductor
SOURCE
) with the other set of probe tips:
= I + I
MEAS1 IN-CKT SOURCE
V
MEAS1
R = -------------------------------------------------
TRACE
I + I
IN-CKT SOURCE
V = I R
MEAS2 IN-CKT TRACE
V
MEAS2
R = ----------------------
TRACE
I
IN-CKT
Y
Note: The distance
"X" must be greater
than 10 times the
x
distance "Y" or
additional errors will
be introduced.
Y
R
TRACE
)
MEAS2