Datasheet

   
      
    ± 
SLAS262C − OCTOBER 2000 − REVISED MAY 2003
18
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analog input mode (continued)
When pseudodifferential mode is selected, only two analog input channel pairs are available for the TLC3574
and TLC2574 and four channel pairs for the TLC3578 and TLC2578, because half the inputs are used as the
negative input.
Analog
MUX
SAR
ADC
X8
†
A0
A1
A2
A3
A4
A5
A6
A7
X4
‡
A0
A1
A2
A3
X
X
X
X
X8
†
A0(+) Pair A
A1(−)
A2(+) Pair B
A3(−)
A4(+) Pair C
A5(−)
A6(+) Pair D
A7(−)
X4
‡
A0(+) Pair A
A1(−)
A2(+) Pair B
A3(−)
Analog
MUX
SAR
ADC
Single Ended Pseudodifferential
†
TLC3578 and TLC2578
‡
TLC3574 and TLC2574
Figure 7. Pin Assignment of Single-Ended Input vs Pseudodifferential Input
reference voltage
The external reference is applied to the reference-input pins (REFP and REFM). REFM should connect to
analog ground. REFP is 4 V. Install decoupling capacitors (10 µF in parallel with 0.1 µF) between REFP and
REFM, and compensation capacitors (0.1 µF) between COMP and AGND.
ideal conversion characteristics
00000000000000
00000000000001
00000000000010
01111111111111
10000000000000
10000000000001
11111111111111
11111111111110
11111111111101
16381
16383
16382
8192
8193
8191
0
1
2
01111111111111
01111111111110
01111111111101
00000000000001
00000000000000
11111111111111
10000000000010
10000000000001
10000000000000
Binary
BOB
2s Complement
BTC
VFS− = −10 V
−9.99939 V
−9.99878 V
−9.99756 V
−0.61 mV
9.99756 V
0.61 mV
VBZS = 0.0 V
VFS+ = 10 V
1LSB = 1.22 mV
Bipolar Analog Input Voltage
Step
Digital Output Code