GENERAL DESCRIPTION

The OP400 is the first monolithic quad operational amplifier that features OP77-type performance. Precision performance is not sacrificed with the OP400 to obtain the space and cost savings offered by quad amplifiers.

The OP400 features an extremely low input offset voltage of less than 150 μV with a drift of less than 1.2 μV/°C, guaranteed over the full military temperature range. Open-loop gain of the OP400 is more than 5 million into a 10 kΩ load, input bias current is less than 3 nA, common-mode rejection (CMR) is more than 120 dB, and power supply rejection ratio (PSRR) is less than 1.8 μV/V. On-chip Zener zap trimming achieves the low input offset voltage of the OP400 and eliminates the need for offset nulling. The OP400 conforms to the industry-standard quad pinout, which does not have null terminals.

The OP400 features low power consumption, drawing less than 725 μA per amplifier. The total current drawn by this quad amplifier is less than that of a single OP07, yet the OP400 offers significant improvements over this industry-standard op amp. Voltage noise density of the OP400 is a low 11 nV/√Hz at 10 Hz, half that of most competitive devices.

The OP400 is an ideal choice for applications requiring multiple precision operational amplifiers and where low power consumption is critical.

 

FEATURES

Low input offset voltage: 150 μV (maximum)

Low offset voltage drift over –55°C to +125°C: 1.2 μV/°C (maximum)

Low supply current (per amplifier): 725 μA (maximum)

High open-loop gain: 5000 V/mV (minimum)

Input bias current: 3 nA (maximum)

Low noise voltage density: 11 nV/√Hz at 1 kHz

Stable with large capacitive loads: 10 nF typical

Available in die form

 

APPLICATIONS INFORMATION

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 . The linearity 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. Common-mode rejection ratio (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. The output signal is specified with respect to the reference input,

which is normally connected to analog ground. The reference input can offset the output from −10 V to +10 V if required.

 

BIPOLAR CURRENT TRANSMITTER

Which is an extension of the standard three op amp instrumentation amplifier, the output current is proportional to the differential input voltage. Maximum output current is ±5 mA, with voltage compliance equal to ±10 V when using ±15 V supplies. Output impedance of the current transmitter exceeds 3 MΩ, and linearity is better than 16 bits with gain set for a full-scale input of ±100 µV.

 

DIFFERENTIAL OUTPUT INSTRUMENTATION AMPLIFIER

The output voltage swing of a single-ended instrumentation amplifier is limited by the supplies, normally at ±15 V, to a maximum of 24 V p-p. The differential output instrumentation amplifier shown in Figure 33 can provide an output voltage swing of 48 V p-p when operated with ±15 V supplies. The extended output swing is due to the opposite polarity of the outputs. Both outputs swing 24 V p-p, but with opposite polarity, for a total output voltage swing of 48 V p-p. The reference input can set a common-mode output voltage over the range ±10 V. The PSRR of the amplifier is less than 1 µV/V with CMRR (G = 1000) better than 115 dB. Offset voltage drift is typically 0.4 µV/°C over the military temperature range.