Datasheet

12
LTC1290
1290fe
U
S
A
O
PP
L
IC
AT
I
WU
U
I FOR ATIO
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
Unipolar Transfer Curve (UNI = 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.
Unipolar Output Code (UNI = 1)
Bipolar Transfer Curve (UNI = 0)
Bipolar Output Code (UNI = 0)
0V 1LSB
V
REF
– 2LSB
V
REF
– 1LSB
V
REF
V
IN
0 0 0 0 0 0 0 0 0 0 0 1
0 0 0 0 0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1 1 1 0
•
•
•
LTC1290 AI04b
OUTPUT CODE
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
INPUT VOLTAGE
V
REF
– 1LSB
V
REF
– 2LSB
•
•
•
1LSB
0V
INPUT VOLTAGE
(V
REF
= 5V)
4.9988V
4.9976V
•
•
•
0.0012V
0V
LTC1290 • AI04a
OUTPUT CODE
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
INPUT VOLTAGE
–1LSB
–2LSB
•
•
•
–(V
REF
) + 1LSB
– (V
REF
)
INPUT VOLTAGE
(V
REF
= 5V)
–0.0024V
–0.0048V
•
•
•
–4.9976V
–5.0000V
OUTPUT CODE
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
INPUT VOLTAGE
V
REF
– 1LSB
V
REF
– 2LSB
•
•
•
1LSB
0V
INPUT VOLTAGE
(V
REF
= 5V)
4.9976V
4.9851V
•
•
•
0.0024V
0V
LTC1290 AI05a
1LSB
V
REF
– 2LSB
V
REF
– 1LSB
V
REF
V
IN
1 1 1 1 1 1 1 1 1 1 1 1
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 0
0 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
–1LSB
–2LSB
–V
REF
–V
REF
+ 1LSB
•
•
•
LTC1290 AI05b