12
LT1078/LT1079
10789fe
APPLICATIONS INFORMATION
WU
U
Matching Specifications
In many applications the performance of a system de-
pends on the matching between two op amps, rather than
the individual characteristics of the two devices. The two
and three op amp instrumentation amplifier configura-
tions shown in this data sheet are examples. Matching
characteristics are not 100% tested on the LT1078/LT1079.
Some specifications are guaranteed by definition. For
example, 70
μV maximum offset voltage implies that mis-
match cannot be more than 140
μV. 97dB (= 14μV/V)
CMRR means that worst-case CMRR match is 91dB
(= 28
μV/V). However, Table 1 can be used to estimate the
expected matching performance at VS = 5V, 0V between
the two sides of the LT1078, and between amplifiers A and
D, and between amplifiers B and C of the LT1079.
Table 1
LT1078AC/LT1079AC/LT1078AM/LT1079AM
LT1078C/LT1079C/LT1078M/LT1079M
PARAMETER
50% YIELD
98% YIELD
50% YIELD
98% YIELD
UNITS
VOS Match, ΔVOS
LT1078
30
110
50
190
μV
LT1079
40
150
50
250
μV
Temperature Coefficient
ΔVOS
0.5
1.2
0.6
1.8
μV/°C
Average Noninverting IB
68
6
10
nA
Match of Noninverting IB
0.12
0.4
0.15
0.5
nA
CMRR Match
120
100
117
97
dB
PSRR Match
117
105
117
102
dB
Comparator Applications
The single supply operation of the LT1078/LT1079 and its
ability to swing close to ground while sinking current
lends itself to use as a precision comparator with TTL
compatible output.
4
VS = 5V, 0V
200
μs/DIV
LT2078/79 F03
2
0
–100
INPUT
(mV)
OUTPUT
(V)
Figure 3. Comparator Rise Response
Time to 10mV, 5mV, 2mV Overdrives
VS = 5V, 0V
200
μs/DIV
LT2078/79 F04
0
100
0
INPUT
(mV)
OUTPUT
(V)
4
2
Figure 4. Comparator Fall Response
Time to 10mV, 5mV, 2mV Overdrives