Fluke 78 - Automotive Measurement Applications; Measuring Voltage and Current

78
Service Manual
2-8
A/D
CONTROL
131.072 kHz
CLOCK
MICROCOMPUTER
CONTROL
SWITCH
NO.
1
2
3
4
5
AUTO
ZERO
ON
ON
INTE-
GRATE
ON
READ
+INPUT
ON
ON
READ
–INPUT
ON
ON
HOLD
ON
ON
+
–
VOLTAGE
REFERENCE
+
BUFFER INTEGRATOR COMPARATOR
3
4
5
1
INPUT
VOLTAGE
2
+
+
–
REFER TO WAVEFORM
COMPARE
8 MINOR CONVERSIONS, 200 ms
(1 FULL RESOLUTION CONVERSION)
AS SEEN AT INTEGRATOR OUTPUT
SAMPLE #1
SAMPLE #2 SAMPLE #8
REPEAT
HOLD
READ
RAMP
INTEGRATE
RAMP
ZERO
BASELINE
AUTO ZERO
16.7
ms
8.33
ms
–
zr04f.eps
Figure 2-4. A/D Converter