Features

● Low -dimensional voltage: maximum 75 μV

● Low offset voltage drift: maximum 1.0 μV/° C [123 123 [123 ]

● Extremely low -pressure current

● 25 ° C: Maximum 150 PA

●

#8722; 40 ° C to+85 ° C: Maximum 300 PA

●

Very high -opening gain: minimum 2000V/mv

● [ 123] Low power current (each amplifier): maximum 625 μA

● Work within the range of the power supply range of ± 2 V to ± 20 V

● [123 123 ] High -common model suppression: minimum 114 db Application

● Response and bridge amplifier

●

High and stable Sexual thermostatic amplifier

●

Instrument amplifier

Optical current monitor

● High Gain linear amplifier

● Long -term integralizer/filter

●

Sample maintenance amplifier

● [123 ] Peak detector

●

Drive amplifier

Battery power supply system

General description OP497 is a four -way computing amplifier, which has precise performance in the 16 leader of the 16 leader of space -saving industrial standards. It combines high -precision, low power consumption and extremely low input bias current, making the four -way OP497 useful in wide applications.

The accuracy of OP497 includes very low offset ( lt; 50μV) and low drift ( lt; 0.5μV/° C). The opening gain of the ring is more than 2000V/MV, ensuring that it is high -line in each application. The error generated by the co -model signal can be suppressed and eliminated by the co -mode greater than 120 decibels. The power supply of OP497 is greater than 120 decibels, which minimizes the offset voltage changes in the battery power supply system. OP497's power supply current lt; 625μA, working voltage is low to ± 2V. OP497 uses an ultra -β input stage with a biased current to maintain the Pipan tubeThere is a bias current at temperature. This is different from the FET input computing amplifier. Its bias current starts within the range of the Pipanus at 25 ° C, but the temperature will double every 10 ° C to reach the milliam of 85 ° C. The input bias current of OP497 is less than 100 PA at 25 ° C.

Combined with accuracy, low power consumption, low bias current, OP497 is an ideal application, including instrument amplifier, a number amplifier, an optical diode front amplifier, and a long -term integralizer. For a single device, see the OP97 data table; for dual device, see the OP297 data table. pin connection

θja for installation in the worst case Conditions, that is, θja specifies the device in the socket for PDIP packaging, and θja specifies the welding of welding to the printed circuit board (PCB) for SOIC packaging.

Typical performance features

TA u003d 25 ° C, vs u003d ± 15 v, unless there are other instructions.

Application information

extremely low low The bias current makes OP497 attractive in the sampling kernel, peak detector, and the number amplifier that must work within the wide temperature range. OP497 does not require a balanced input resistance. High -source resistance, even in the case of imbalance, will only reduce the offset voltage and TCVOS to a minimum.

The input pins of OP497 are protected by the back diode and a current -limited resistance of the back to prevent a large differential voltage. The co -mode voltage of the input terminal is not limited and may change within the entire range of the power supply voltage used.

OP497 is very small for the operation of the power rail, and it is stipulated that it runs when the power supply voltage is low to ± 2 V. Generally, the scope of the co -mode extends to the 1V range of any orbit. When using a 10kΩ load, the output is usually swinging in the rail 1V range. AC performance The communication characteristics of OP497 are highly stable in the entire working temperature range. Figure 30 shows a small signal response of the unit gain. OP497 has extremely high tolerance for the capacitance load at the output end, and excellent response is displayed even under the 1000 PF load (see Figure 31).

Protection and shielding

In order to keep OP497 extremely highThe input impedance must be careful in the layout and manufacturing of the circuit board. The surface of the board must be kept clean and no moisture. It is recommended to use the shelf coating to provide a moisture -proof layer. Even a clean PCB may have a leakage current of 100Pa between adjacent lines; therefore, the protection ring is used around the input end. As shown in Figure 34, the protection tracking runs under the voltage close to the input voltage to minimize the leakage current. In non -switching applications, the protective ring is connected to the co -mode voltage at the inverter input terminal. In reverse applications, both inputs remain on the ground; therefore, the protection tracking should be grounded. Place protective marks on both sides of the circuit board.

Open -loop gain linearity

OP497 has a typical 2000V/MV extremely high gain and constant gain linear. This improves the accuracy of OP497 and provides very high accuracy in the high -closed cycle gain application. Figure 35 illustrates the typical opening gain of OP497.

Application circuit

Precision absolute value Putting large device

The circuit in FIG Essence OP497's high gain and low TCVO ensure the precise operation of the micro -input signal. In this circuit, input always appears as a public mode signal on the operation amplifier. OP497's CMR is more than 120dB, and the error is less than 2PPM.

Precision current pump

Figure 37 The maximum output current shown in FIG. 37 is ± 10 mAh. For ± 15 V power, the voltage compliance is ± 10 V. The output impedance of the current transmitter exceeds 3MΩ, and the linearity is better than 16 bits.

Precision Positive Peak Values u200bu200b

In FIG. 38, CH must be polystyrene, Teflon #174; Try to reduce the absorption and leakage of the medium. The drooping rate is determined by the size of CH and the bias current of OP497.

Simple bridge regulatory amplifier

FIG. 39 shows a simple bridge regulatory amplifier using OP497. The transmission function is:

Ref43 provides precise and stable reference voltage for the bridge. In order to maintain the highest circuit accuracy, RF should be 0.1%or better, and the temperature factor is low.

Non -linear circuit

Due to its low input bias current, OP497 is an ideal pair amplifier in non -linear circuit, as shown in Figures 40 and Figure 41 Showed the square and square -bonfall circuit. In Figure 40's squareAs an example, the amplifier circuit is an analysis. First, the voltage ring equation of the transistor Q1, Q2, Q3, and Q4 is written.

All the crystals in MAT04 are accurately matched and at the same temperature; therefore, IS and VT items disappear, and get:

Seeking the power on both sides of the thick equation will lead to

The operation amplifier A2 forms an current-voltage converter, the result is VOUT u003d R2 × IO. Use (VIN/R1) instead of IIN, and use a equation instead of IO:

Similar analysis is obtained from its transmission function

In these circuits, Iref is a function of negative power supply. In order to maintain accuracy, negative power should be adjusted well. For applications that need to be very accurate, you can use reference voltage to set iRef. An important consideration is that a sufficiently large input voltage can force the output to exceed the scope of the output operation amplifier. The resistor R4 can be changed to the scale IRF, or R1 and R2 can be changed to keep the output voltage within the available range.

In the input voltage range of 100MV ~ 10V, the unsettled accuracy of the square root circuit is better than 0.1%. 0.5%.

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