LT1677 LINER [Linear Technology], LT1677 Datasheet - Page 9

• Manufacturer Part Number: LT1677
• Description: Low Noise, Rail-to-Rail Precision Op Amp
• Manufacturer: LINER [Linear Technology]

APPLICATIO S I FOR ATIO
General
The LT1677 series devices may be inserted directly into
OP-07, OP-27, OP-37 and sockets with or without removal
of external compensation or nulling components. In addi-
tion, the LT1677 may be fitted to 741 sockets with the
removal or modification of external nulling components.
Rail-to-Rail Operation
To take full advantage of an input range that can exceed
the supply, the LT1677 is designed to eliminate phase
reversal. Referring to the photographs shown in Figure 1,
the LT1677 is operating in the follower mode (A
a single 3V supply. The output of the LT1677 clips cleanly
and recovers with no phase reversal. This has the benefit
of preventing lock-up in servo systems and minimizing
distortion components.
Offset Voltage Adjustment
The input offset voltage of the LT1677 and its drift with
temperature are permanently trimmed at wafer
testing to a low level. However, if further adjustment of
V
will not degrade drift with temperature. Trimming to a
value other than zero creates a drift of (V
e.g., if V
1 V/ C (Figure 2).
OS
is necessary, the use of a 10k nulling potentiometer
– 0.5V
OS
3V
2V
1V
0V
is adjusted to 300 V, the change in drift will be
Input = – 0.5V to 3.5V
U
Figure 1. Voltage Follower with Input Exceeding the Supply Voltage (V
U
W
OS
1577 F01a
/ 300) V/ C,
U
V
= +1) at
The adjustment range with a 10k pot is approximately
ity and resolution of the nulling can be improved by using
a smaller pot in conjunction with fixed resistors. The
example has an approximate null range of
(Figure 3).
2.5mV. If less adjustment range is needed, the sensitiv-
– 0.5V
3V
2V
1V
0V
Figure 3. Improved Sensitivity Adjustment
INPUT
Figure 2. Standard Adjustment
4.7k
2
3
2
3
–
+
LT1677
1
LT1677 Output
–
+
–15V
LT1677
1
–15V
8
4
1k
4.7k
S
10k
8
4
= 3V)
7 6
7
6
15V
15V
OUTPUT
1677 F03
OUTPUT
1677 F02
1577 F01b
LT1677
200 V
9