MAX155(2012) 查看數據表（PDF） - Maxim Integrated
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MAX155 Datasheet PDF : 20 Pages
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MAX155/MAX156
8-/4-Channel ADCs with Simultaneous
T/Hs and Reference
Multiplexer and A/D Configuration
A conversion is started with a WR pulse. All channels
sample on WR’s falling edge. Mux configuration data is
loaded on WR’s rising edge. In I/O mode (MODE = Open
Circuit), selections for channel number, singleor multi-
channel conversion, unipolar or bipolar input, and single-
ended or differential input are made with A0-A2, ALL, BIP,
and DIFF (Table 1). These input pins are also shared with
the RAM data outputs D0–D7. An alternate, simpler inter-
face is provided by the hard-wired mode, which selects
some general mux configurations without requiring ADC
programming. Hard-wired connections of MODE and VSS
select from 4 mux configurations as listed in Table 4 (see the
Hard-Wired Mode section).
On the rising edge of WR, the mux configuration register
is updated; falling edge initiates sampling of all inputs.
A channel selection can be implemented on the current
conversion, but changes from unipolar to bipolar (with
BIP) or from singleended to differential operation (with
DIFF) do not go into effect until the following WR. This can
be overcome by writing to the configuration register while
inhibiting the conversion (INH = 1), or by changing DIFF
and BIP one conversion early, i.e. on the previous write.
Table 2. Single-Ended Channel Selection (MODE = Open Circuit)
MUX ADDRESS
A0
A1
A2
DIFF
0
1
0
0
0
0
+
1
0
0
0
+
0
1
0
0
1
1
0
0
0
0
1
0
1
0
1
0
0
1
1
0
1
1
1
0
Note: Shaded areas represent MAX156 operation.
SINGLE-ENDED CHANNEL SELECTION
2
3
4
5
6
+
+
+
+
+
7
AGND
-
-
-
-
-
-
-
+
-
Table 3. Differential Channel Selection (MODE = Open Circuit)
MUX ADDRESS
DIFFERENTIAL CHANNEL SELECTION
A0
A1
A2
DIFF
0
1
2
3
4
5
6
7
0
0
0
1
+
-
0
1
0
1
+
-
0
0
1
1
+
-
0
1
1
1
+
-
1
0
0
1
-
+
1
1
0
1
-
+
1
0
1
1
-
+
1
1
1
1
Note: Shaded areas represent MAX156 operation.
-
+
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