Data Sheet

OP400

Rev. H | Page 11 of 16

APPLICATIONS

The OP400 is inherently stable at all gains and is capable of

driving large capacitive loads without oscillating. Nonetheless,

good supply decoupling is highly recommended. Proper supply

decoupling reduces problems caused by supply line noise and

improves the capacitive load-driving capability of the OP400.

Total supply current can be reduced by connecting the inputs of

an unused amplifier to V−. This turns the amplifier off,

lowering the total supply current.

DUAL LOW POWER INSTRUMENTATION

AMPLIFIER

A dual instrumentation amplifier that consumes less than

33 mW of power per channel is shown in Figure 31. The linear-

ity of the instrumentation amplifier exceeds 16 bits in gains of 5 to

200 and is better than 14 bits in gains from 200 to 1000. CMRR

is above 115 dB (G = 1000). Offset voltage drift is typically

0.4 μV/°C over the military temperature range, which is

comparable to the best monolithic instrumentation amplifiers.

The bandwidth of the low power instrumentation amplifier is

a function of gain and is shown in Table 6.

The output signal is specified with respect to the reference

input, which is normally connected to analog ground. The

reference input can be used to offset the output from −10 V to

+10 V if required.

Table 6. Gain Bandwidth

Gain

Bandwidth

5

150 kHz

10

67 kHz

100

7.5 kHz

1000

500 Hz

–

+

20kΩ

5kΩ

5kΩ

20kΩ

REFERENCE

–

+

20kΩ

5kΩ

5kΩ

20kΩ

REFERENCE

40,000

= 5 +

1/4

OP400A

+

–

1/4

OP400A

+

–

1/4

OP400A

+

–

1/4

OP400A

+

–

Figure 31. Dual Low Power Instrumentation Amplifier