9

LT1677

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,

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

will not degrade drift with temperature. Trimming to a

1

µV/°C (Figure 2).

The adjustment range with a 10k

Ω pot is approximately

±2.5mV. If less adjustment range is needed, the sensitiv-

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

±200µV

(Figure 3).

Input = – 0.5V to 3.5V

LT1677 Output

3V

2V

1V

0V

– 0.5V

1577 F01a

3V

2V

1V

0V

– 0.5V

1577 F01b

Figure 3. Improved Sensitivity Adjustment

Figure 2. Standard Adjustment

1677 F02

10k

OUTPUT

INPUT

8

7

6

4

1

2

3

15V

–15V

LT1677

1677 F03

1k

4.7k

OUTPUT

8

7 6

4

1

2

3

15V

–15V

LT1677

4.7k