LTC1404 LINER [Linear Technology], LTC1404 Datasheet - Page 14

• Manufacturer Part Number: LTC1404
• Description: Complete SO-8, 12-Bit, 600ksps ADC with Shutdown
• Manufacturer: LINER [Linear Technology]

APPLICATIONS
LTC1404
14
Figure 8. LTC1404 Unipolar Transfer Characteristics
V
ADDITIONAL PINS OMITTED FOR CLARITY
Figure 9. LTC1404 Bipolar Transfer Characteristics
IN
20LSB TRIM RANGE
Figure 10a. LTC1404 Full-Scale Adjust Circuit
011...111
011...110
000...001
000...000
111...111
111...110
100...001
100...000
111...111
111...110
111...101
111...100
000...011
000...010
000...001
000...000
50
R1
0V
R2
10k
–FS/2
UNIPOLAR
ZERO
1LSB = FS
LSB
1
U
4096
R3
10k
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
INFORMATION
+
–
U
=
4.096
BIPOLAR
4096
A1
LSB
–1
ZERO
0V
100
R4
FULL-SCALE
LSB
ADJUST
1
W
FS/2 – 1LSB
FS – 1LSB
1404 F08
1404 F09
A
GND
LTC1404
IN
1404 F10a
U
Bipolar Offset and Full-Scale Error Adjustments
Bipolar offset and full-scale errors are adjusted in a similar
fashion to the unipolar case. Bipolar offset error adjust-
ment is achieved by applying an input voltage of – 0.5mV
(– 0.5LSB) to the input in Figure 10c and adjusting the op
amp until the ADC output code flickers between 0000 0000
0000 and 1111 1111 1111. For full-scale adjustment, an
input voltage of 2.0465V (FS – 1.5LSBs) is applied to the
input and R5 is adjusted until the output code flickers
between 0111 1111 1110 and 0111 1111 1111.
Figure 10c. LTC1404 Bipolar Offset and Full-Scale Adjust Circuit
0V TO 4.096V
ANALOG
2.048V
Figure 10b. LTC1404 Offset and Full-Scale Adjust Circuit
INPUT
ANALOG
INPUT
5V
10k
R1
10k
10k
R1
R2
10k
R2
10k
R9
20
+
–
+
–
A1
A1
R4
100k
R5
4.3k
FULL-SCALE
ADJUST
R3
100k
R6
200
R3
100k
R4
100k
R5
4.3k
FULL-SCALE
ADJUST
R6
400
100k
R7
100k
R7
A
LTC1404
–5V
IN
5V
A
LTC1404
IN
R8
20k
OFFSET
ADJUST
5V
1404 F10c
R8
10k
OFFSET
ADJUST
1404 F10b