MX7575 MAXIM [Maxim Integrated Products], MX7575 Datasheet - Page 11

• Manufacturer Part Number: MX7575
• Description: CMOS, uP-Compatible, 5?s/10?s, 8-Bit ADCs
• Manufacturer: MAXIM [Maxim Integrated Products]

Figure 18a. MX7575 Bipolar Configuration
To minimize noise coupling, keep both the input signal
lead to AIN and the signal return lead from AGND as
short as possible. If this is not possible, a shielded
cable or a twisted-pair transmission line is recommend-
ed. Additionally, potential differences between the ADC
ground and the signal-source ground should be mini-
mized, since these voltage differences appear as
errors superimposed on the input signal. To minimize
system noise pickup, keep the driving source resis-
tance below 2kΩ.
For PC board layouts, take care to keep digital lines
well separated from any analog lines. Establish a sin-
gle-point, analog ground (separate from the digital sys-
tem ground) near the MX7575/MX7576. This analog
ground point should be connected to the digital system
ground through a single-track connection only. Any
supply or reference bypass capacitors, analog input fil-
ter capacitors, or input signal shielding should be
returned to the analog ground point.
0.1 F
__________Applications Information
47 F
+
CMOS, µP-Compatible, 5µs/10µs, 8-Bit ADCs
3.3k
REFERENCE
R6
ICL8069
1.2V
+5V
______________________________________________________________________________________
R7
10k
+5V
+5V
47 F
TLC271
8.2k
R5
R4
5k
INPUT VOLTAGE
R1
1k
R2
820
R3
500
0.1 F
17
16
Proper Layout
AGND DGND
REF
AIN
15
MX7575
18
V
DD
9
CLK
5
D7–D0
DATA OUT
+5V
Noise
R
C
100pF
2%
CLK
L
Figure 18b. Nominal Transfer Characteristic for Bipolar
Operation
__Functional Diagrams (continued)
MODE
AGND
CLK
REF
AIN
CS
RD
16
15
17
5
1
2
3
111...111
111...110
100...010
100...001
100...000
011...111
011...110
000...001
000...000
MX7576
OSCILLATOR
CLOCK
OUTPUT
CODE
BUSY
4
-FS
2
CONTROL
LOGIC
-1/2LSB
DAC
SAR
1/2LSB
OUTPUT DRIVERS
THREE-STATE
LATCH AND
FS = 2V
1LSB =
FS
2
COMP
-1LSB
REF
18
2FS
256
DGND
9
V
DD
AIN
6
14
D7
D0
. .
11