ADC08034 National Semiconductor, ADC08034 Datasheet - Page 11

• Manufacturer Part Number: ADC08034
• Description: 8-Bit High-Speed Serial I/O A/D Converters with Multiplexer Options/ Voltage Reference/ and Track/Hold Function
• Manufacturer: National Semiconductor

Single-Ended MUX Mode
Differential MUX Mode
START
START
Functional Description
enabled and whether this input is single-ended or differential.
Differential inputs are restricted to adjacent channel pairs.
For example, channel 0 and channel 1 may be selected as a
differential pair but channel 0 or 1 cannot act differentially
with any other channel. In addition to selecting differential
mode the polarity may also be selected. Channel 0 may be
selected as the positive input and channel 1 as the negative
input or vice versa. This programmability is best illustrated by
the MUX addressing codes shown in the following tables for
the various product options.
The MUX address is shifted into the converter via the DI line.
Because the ADC08031 contains only one differential input
channel with a fixed polarity assignment, it does not require
addressing.
The common input line (COM) on the ADC08038 can be
used as a pseudo-differential input. In this mode the voltage
on this pin is treated as the “−” input for any of the other input
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
SGL/
DIF
SGL/
1
1
1
1
1
1
1
1
DIF
MUX Address
0
0
0
0
0
0
0
0
MUX Address
ODD/
SIGN
0
0
0
0
1
1
1
1
ODD/
SIGN
0
0
0
0
1
1
1
1
1
0
0
1
1
0
0
1
1
SELECT
(Continued)
1
0
0
1
1
0
0
1
1
SELECT
TABLE 2. MUX Addressing: ADC08038
TABLE 3. MUX Addressing: ADC08038
0
0
1
0
1
0
1
0
1
0
0
1
0
1
0
1
0
1
+
0
0
+
−
11
1
+
0
channels. This voltage does not have to be analog ground; it
can be any reference potential which is common to all of the
inputs. This feature is most useful in single-supply applica-
tions where the analog circuity may be biased up to a poten-
tial other than ground and the output signals are all referred
to this potential.
ADC08031
ADC08032
ADC08034
ADC08038
1
−
+
Number
Part
2
+
Analog Single-Ended Channel #
Analog Differential Channel-Pair #
TABLE 1. Multiplexer/Package Options
2
+
−
Single-Ended
3
+
1
Number of Analog
1
2
4
8
3
−
+
4
+
Channels
+
−
4
5
+
Differential
2
1
1
2
4
6
+
5
−
+
Number of
Package
7
+
www.national.com
6
+
−
Pins
14
20
8
8
3
COM
−
−
−
−
−
−
−
−
7
−
+