Datasheet

External and Internal References
The MAX1202 can be used with an internal or external
reference, whereas an external reference is required for
the MAX1203. An external reference can be connected
directly at the REF terminal, or at the REFADJ pin.
An internal buffer is designed to provide 4.096V at REF
for both the MAX1202 and the MAX1203. The MAX1202’s
internally trimmed 2.44V reference is buffered with a gain
of 1.68. The MAX1203’s REFADJ pin is buffered with
a gain of 1.64, to scale an external 2.5V reference at
REFADJ to 4.096V at REF.
MAX1202 Internal Reference
The MAX1202’s full-scale range using the internal refer-
ence is 4.096V with unipolar inputs and ±2.048V with
bipolar inputs. The internal reference voltage is adjustable
to ±1.5% with the circuit of Figure 17.
Figure 12b. Timing Diagram for Power-Down Modes, Internal Clock
Figure 13. MAX1202 FULLPD/FASTPD Power-Up Sequence
Figure 12c. Additional I
DD
Shutdown Supply Current vs. V
IH
for
Each Digital Input at a Logic 1
FULL
POWER-DOWN
POWERED
UP
POWERED UP
DATA VALID
DATA VALID
INTERNAL CLOCK MODE
S X
X X X X
1 0 S 0 0
X XXXX
S
MODE
DOUT
DIN
CLOCK
MODE
SETS INTERNAL
CLOCK MODE
SETS FULL
POWER-DOWN
CONVERSION
CONVERSION
SSTRB
1 0 0
DIN
REFADJ
REF
2.5V
0V
4V
0V
1 0 1 1 11 1 0 0 1 0 1
FULLPD FASTPD NOPD FULLPD FASTPD
COMPLETE CONVERSION SEQUENCE
t
BUFFEN
ª 15µs
t = RC = 20kW x C
REFADJ
(ZEROS)
CH1 CH7
(ZEROS)
2ms WAIT
0
-60
10
5
TEMPERATURE (°C)
SUPPLY CURRENT PER INPUT (mA)
100
25
20
15
-20 60 140
40
35
30
20
(V
DD
- V
IH
) = 1.95V
(V
DD
- V
IH
) = 2.55V
(V
DD
- V
IH
) = 2.25V
MAX1202/MAX1203 5V, 8-Channel, Serial, 12-Bit ADCs
with 3V Digital Interface
www.maximintegrated.com
Maxim Integrated
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