HP 3465B - Page 19

Model 3465B
Section IV
A—D converter description of the integrator, slope ampli-'
fier and auto-zero circuit in the simplified theory. Figure
4-7, Functional Diagram, A—D Converter, illustrates these
circuits in relation to the monopolar reference supply, the
input amplifier and the comparator. It also illustrates the
integrator output and the four control state signals, IZ, 10,
11 and 12, with respect to the measurement sequence
intervals.
COMPARATOR
INPUT.
FROM
SIGNAL
CONDITIONING
SECTION
20 mVdc to 2 Vdc
FULL—SCALE)
MONOPOLAR
REF SUPPLY
+ IOV
INTEGRATOR
INPUT AMP
SLOPE AMP
lOOK
vs/v
LOGIC
X4000
FULL-SCALE
SECTION
2 Vdc
42 K 500k|
AUTO-ZERO
OOFF
-NOTE-
A-D CONVERTER
SHOWN IN AUTO
ZERO MODE
C4
AUTO-ZERO
CAPACITOR
3465-B-4I69
, AUTO-ZERO ,
I 0.1 SEC I
RUN-UP
0.1 SEC
INTEGRATOR
OUTPUT
RUN-DOWN
0.1 SEC
NEGAT VE
/INPUTS
OVERRANGE
0.1 SEC
, OVERLOAD ,
I 0.1 SEC I
ONS OV
OFFS -7V
/
/VTs POSITIVE
\ / INPUTS
IZ
10
11
12
ON-
OFF
ON
OFF-
ON-
OFF
ON
OFF -
MEASUREMENT
INTERVAL
INPUT
SIGNAL
POLARITY
STATE OF
CURRENT SWITCH
11
12
AUTO-ZERO
+
CLOSED
CLOSED
OPEN
OPEN
RUN-UP
+
CLOSED
CLOSED
OPEN
OPEN
RUN-DOWN
+
OPEN
CLOSED
OPEN
CLOSED
Figure 4-7. Functional Diagram, A—D Converter.
4-7