Datasheet

Data Sheet ADAS3023
Figure 38. Complete 5 V, Single-Supply, 8-Channel Data Acquisition System with PGIA
TYPICAL APPLICATION CONNECTION DIAGRAM
As shown in Figure 38, the ADP1613 is used in an inexpensive
SEPIC-Ćuk topology, which is an ideal candidate for providing
the ADAS3023 with the necessary high voltage ±15 V robust
supplies (at 20 mA) and low output ripple (3 mV maximum) from
an external 5 V supply. The ADP1613 satisfies the specification
requirements of the ADAS3023 using minimal external compo-
nents yet achieves greater than 86% efficiency. See the CN-0201
circuit note for complete information about this test setup.
ANALOG INPUTS
Input Structure
The ADAS3023 uses a differential input structure between each
of the channel inputs, IN0 to IN7, and a common reference
(COM), all of which sample simultaneously.
Figure 39 shows an equivalent circuit of the inputs. The diodes
provide ESD protection for the analog inputs (IN0 to IN7) and
COM from the high voltage supplies (VDDH and VSSH). Ensure
that the analog input signal does not exceed the supply rails by
more than 0.3 V because this can cause the diodes to become
forward-biased and to start conducting current. The voltages
beyond the absolute maximum ratings may cause permanent
damage to the ADAS3023 (see Table 4).
Figure 39. Equivalent Analog Input Circuit
Programmable Gain
The ADAS3023 incorporates a programmable gain instru-
mentation amplifier (PGIA) with four selectable ranges. The
PGIA settings are specified in terms of the maximum absolute
differential input voltage across an input pin and the COM pin,
for example INx to COM. The power on and default conditions
are preset to the ±20.48 V (PGIA = 11) input range.
Note that because the ADAS3023 can use any input type, such
as bipolar single-ended and pseudo bipolar, setting the PGIA is
important to make full use of the allowable input span.
IN0
IN1
IN2
IN3
IN4
IN5
IN6
IN7
DIFF TO
COM
LOGIC/
INTERFACE
REFIN
REF
CNV
RESET
SCK
DIN
SDO
VDDH
AVDD DVDD
VIO
CS
COM
BUSY
+
+
+
ENABLE
ADP1613
ADAS3023
COMP
FB FREQ
EN VIN
GND
SS
SW
+
+
V
IN
= +5V
+
+
+
+
VSSH
RF2
4.22kΩ
RF1B
47.5kΩ
R
C
1
100kΩ
C
C
1
12nF
C
C
2
10pF
C
V
5
1µF
R
EN
R
B
0
1Ω
R
S
1
0Ω
R
S
2
DNI
C
SS
1µF
Z1
C
IN
1µF
D1
D2
C1
1µF
C2
1µF
L3
1µF
C
OUT
3
4.7µF
C
OUT
1
1µF
C
OUT
2
2.2µF
+15V
–15V
+5V
ADR434
REFx
PD
AGND DGND
AD8031
4.096V
+
–
1.78Ω
R
FILT
DNI
50kΩ
L1
47µH
L2
47µH
+
+5V
+5V
BUF
10942-200
PGIA
PulSAR
ADC
TRACK
AND
HOLD
C
PIN
INx OR COM
VSSH
AGND
VDDH
PGIA
10942-010
TRACK
AND
HOLD
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