LTC1294BCN View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LTC1294BCN Datasheet PDF : 28 Pages
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LTC1293/LTC1294/LTC1296
APPLICATI S I FOR ATIO
Bipolar Transfer Curve (UNI = 0)
OUTPUT CODE INPUT VOLTAGE
011111111111
011111111110
•
•
•
000000000001
000000000000
VREF – 1LSB
VREF – 2LSB
•
•
•
1LSB
0V
INPUT VOLTAGE
(VREF = 5V)
4.9976V
4.9851V
•
•
•
0.0024V
0V
OUTPUT CODE INPUT VOLTAGE
111111111111
111111111110
•
•
•
100000000001
100000000000
–1LSB
–2LSB
•
•
•
–(VREF) + 1LSB
– (VREF)
INPUT VOLTAGE
(VREF = 5V)
–0.0024V
–0.0048V
•
•
•
–4.9976V
–5.00000V
LTC1293 AI04a
Bipolar Output Code (UNI = 0)
011111111111
011111111110
•
•
•
000000000001
000000000000
111111111111
111111111110
•
•
•
100000000001
100000000000
VIN
LTC1293 AI04b
The following discussion will demonstrate how the two
reference pins are to be used in conjunction with the
analog input multiplexer. In unipolar mode the input span
of the A/D is set by the difference in voltage on the REF+ pin
and the REF– pin. In the bipolar mode the input span is
twice the difference in voltage on the REF+ pin and the
REF – pin. In the unipolar mode the lower value of the input
span is set by the voltage on the COM pin for single-ended
inputs and by the voltage on the minus input pin for
differential inputs. For the bipolar mode of operation the
voltage on the COM pin or the minus input pin set the
center of the input span.
The upper and lower value of the input span can now be
summarized in the following table:
INPUT
CONFIGURATION
UNIPOLAR MODE BIPOLAR MODE
Single-Ended Lower Value COM
–(REF+ – REF–) + COM
Upper Value (REF+ – REF–) + COM (REF+ – REF–) + COM
Differential
Lower Value IN–
–(REF+ – REF–) + IN–
Upper Value (REF+ – REF–) + IN – (REF+ – REF–) + IN–
The reference voltages REF+ and REF– can fall between
VCC and V–, but the difference (REF+ – REF –) must be less
than or equal to VCC. The input voltages must
LoTr Ce1q2u9al3toREVFC–C=an0dV.greater than or equal to
be less than
V–. For the
The following examples are for a single-ended input con-
figuration.
Example 1: Let VCC = 5V, V– = 0V, REF+ = 4V, REF– = 1V
and COM = 0V. Unipolar mode of operation. The resulting
input span is 0V ≤ IN+ ≤ 3V.
12
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