MAX1202 Datasheet, PDF (21/24 Pages) Maxim Integrated Products – 5v, 8-cHANNEL, sERIAL, 12-bIT adcS WITH 3v dIGITAL iNTERFACE

5V, 8-Channel, Serial, 12-Bit ADCs
with 3V Digital Interface
OUTPUT CODE
11 . . . 111
11 . . . 110
11 . . . 101
FULL-SCALE
TRANSITION
FS = +4.096V
1LSB = + ^4.096V
4096
00 . . . 011
00 . . . 010
00 . . . 001
00 . . . 000
012 3
FS
INPUT VOLTAGE (LSBs)
FS - 3/2LSB
Figure 15. Unipolar Transfer Function, 4.096V = Full Scale
OUTPUT CODE
011 . . . 111
011 . . . 110
000 . . . 010
000 . . . 001
000 . . . 000
111 . . . 111
111 . . . 110
111 . . . 101
FS = +2.048V
1LSB
=
+4.096V
4096
100 . . . 001
100 . . . 000
-FS
0V
INPUT VOLTAGE (LSBs)
+FS - 1LSB
Figure 16. Bipolar Transfer Function, ±4.096V/2 = Full Scale
(“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 pos-
sible for noise-free operation.
High-frequency noise in the power supplies can affect
the ADC’s high-speed comparator. Bypass these sup-
plies 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.
+5V
100k
24k
510k
0.01µF
MAX1202
REFADJ
12
Figure 17. MAX1202 Reference-Adjust Circuit
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