Datasheet
(“star” ground point) at GND. Connect all other analog
grounds to this ground. No other digital system ground
should be connected to this single-point analog ground.
The ground return to the power supply for this ground
should be low impedance and as short as possible for
noise-free operation.
High-frequency noise in the power supplies can affect the
ADC’s high-speed comparator. Bypass these supplies
to the single-point analog ground with 0.1μF and 4.7μF
bypass capacitors close to the MAX1202/MAX1203.
Minimize capacitor lead lengths for best supply-noise
rejection. If the +5V power supply is very noisy, a 10Ω
resistor can be connected as a lowpass filter, as shown
in Figure 18.
Figure 15. Unipolar Transfer Function, 4.096V = Full Scale Figure 16. Bipolar Transfer Function, ±4.096V/2 = Full Scale
Figure 17. MAX1202 Reference-Adjust Circuit
OUTPUT CODE
FULL-SCALE
TRANSITION
11 . . . 111
11 . . . 110
11 . . . 101
00 . . . 011
00 . . . 010
00 . . . 001
00 . . . 000
1 2 3
0
FS
FS - 3/2LSB
+4.096V
+
4.096V
4096
FS =
1LSB =
INPUT VOLTAGE (LSBs)
011 . . . 111
OUTPUT CODE
011 . . . 110
000 . . . 010
000 . . . 001
000 . . . 000
111 . . . 111
111 . . . 110
111 . . . 101
100 . . . 001
100 . . . 000
-FS
0V
INPUT VOLTAGE (LSBs)
+FS - 1LSB
FS = +2.048V
1LSB =
+4.096V
4096
+5V
510kΩ
100kΩ
24kΩ
0.01µF
12
REFADJ
MAX1202
MAX1202/MAX1203 5V, 8-Channel, Serial, 12-Bit ADCs
with 3V Digital Interface
www.maximintegrated.com
Maxim Integrated
│
21