LTC1289 Linear Technology, LTC1289 Datasheet - Page 11

• Manufacturer Part Number: LTC1289
• Description: 3 Volt Single Chip 12-Bit Data Acquisition System
• Manufacturer: Linear Technology

Unipolar/Bipolar (UNI)
The fifth input bit (UNI) determines whether the conver-
sion will be unipolar or bipolar. When UNI is a logical one,
a unipolar conversion will be performed on the selected
A
PPLICATI
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 0
0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0
OUTPUT CODE
Unipolar Output Code (UNI = 1)
•
•
•
O
0 1 1 1 1 1 1 1 1 1 1 1
0 1 1 1 1 1 1 1 1 1 1 0
0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0
U
INPUT VOLTAGE
OUTPUT CODE
V
V
S
REF
REF
1LSB
0V
– 1LSB
– 2LSB
•
•
•
•
•
•
I FOR ATIO
U
INPUT VOLTAGE
(V
INPUT VOLTAGE
REF
2.4994V
2.4988V
0.0006V
V
V
W
REF
REF
0V
= 2.5V)
1LSB
•
•
•
0V
– 1LSB
– 2LSB
LTC1289 AI04a
•
•
•
0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0
0 1 1 1 1 1 1 1 1 1 1 1
0 1 1 1 1 1 1 1 1 1 1 0
Bipolar Transfer Curve (UNI = 0)
Bipolar Output Code (UNI = 0)
INPUT VOLTAGE
U
(V
•
•
•
REF
2.4988V
2.4976V
0.0012V
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 0
0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0
0V
= 2.5V)
•
•
•
•
•
•
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 0
1 0 0 0 0 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1 1 1 1 1
input voltage. When UNI is a logical zero, a bipolar conver-
sion will result. The input span and code assignment for
each conversion type are shown in the figures below.
1 1 1 1 1 1 1 1 1 1 1 0
1 0 0 0 0 0 0 0 0 0 0 1
1 0 0 0 0 0 0 0 0 0 0 0
OUTPUT CODE
Unipolar Transfer Curve (UNI = 1)
•
•
•
•
•
•
INPUT VOLTAGE
–(V
REF
– (V
–2LSB
–1LSB
) + 1LSB
•
•
•
REF
)
INPUT VOLTAGE
(V
REF
–0.0012V
–0.0024V
–2.4988V
–2.5000V
= 2.5V)
•
•
•
LTC1289 AI05a
LTC1289 AI05b
LTC1289
V
IN
LTC1289 AI04b
11
V
IN