Features

Low -voltage noise: 1 kHz is 1.1 nv/√Hz

Input voltage noise: 80 nvpp (0.1 Hz to 10 Hz) [ 123]

THD+N: - 136DB (g u003d 1, f u003d 1 kHz)

offset voltage: 350 μV (maximum)

#8226; offset voltage drift: 0.35μV/° C (typical value)

Low power current: 6 mA/CH (maximum)

unified gain; unified gain Stability

gain bandwidth product:

80 MMH (g u003d 100)

45 MMH (G u003d 1)

#8226 ; Conversion rate: 27 v/μs

16 -bit settings: 700 ns

Wide power supply range: ± 2.25 V to ± 18 V, 4.5 V to 36 V

Rail transversion

output current: 30 ma

123]

High temperature environment

Support extreme temperature application

Control baseline

123]

A manufacturing site

Extreme temperature range (-55 ° C/150 ° C); (1), custom temperature range

extend the product life cycle

extend the product change notice

Product traceability

Texas Instruments High -temperature product The highly optimized silicon (mold) solution has a design and process improvement function, which can maximize performance at the maximum extension of the temperature.

Explanation

OPA2211 is a precision operational amplifier with a power supply of only 3.6 mAh, which can achieve extremely low 1.1 NV/√Hz noise density. The device also provides rails to orbit swing, maximizing the dynamic range.

The extremely low voltage and low -current noise, high speed and wide output swing of OPA2211 make the device PLLThe best choice of the Central Detland filter amplifier.

In the precision data acquisition application, OPA2211 provides a stable time of 700 nan seconds during the 10-V output swing, reaching 16-bit accuracy. This communication performance, plus only 240 μV's offset and temperature drift of 0.35 μV/° C, makes OPA2211 a driver of high -precision 16 -bit modulus converter (ADC) or cushioning high -resolution digital modulus converter (DAC). The ideal choice of output.

OPA2211 is suitable for a wide dual -power supply range of ± 2.25 V to ± 18 V, or a single power operation of 4.5 V to 36 V.

The specified range of this operation amplifier is TJ u003d -55 ° C to 150 ° C.

Typical features

When TA u003d+25 ° C, vs u003d ± 18V, RL u003d 10K

] Application information OPA22211 is a very low noise of a unit gain stable and accurate computing amplifier. In the application of noise or high impedance power supply, an outdated capacitor that needs to be close to the device pin. In most cases, 0.1 μF capacitors are sufficient. Figure 40 shows the simplified schematic diagram of OPA22211. The mold uses the SIGE bipolar process, which contains 180 transistors. Working voltage OPA222211 series operation ampel work between ± 2.25V to ± 18V power supply while maintaining good performance. The operating voltage of the OPA211 series between the power supply is only+4.5V, and the voltage between the power supply can reach+36V. However, some applications do not need to wait for the positive and negative output voltage to swing. For the OPA22211 series, the power supply voltage does not need to be equal. For example, the positive power supply can be set to+25V, and the negative electrode power supply is -5V, and vice versa. Public mode voltage must be kept within the specified range. In addition, key parameters are guaranteed within the specified temperature range, TJ u003d --55 ° C to+150 ° C. The typical feature shows a significant parameter with the operating voltage or temperature.

Input protection

The input terminal of OPA2211 to prevent excessive differential voltage through the back -to -back diode, as shown in Figure 41. In most circuit applications, there are no consequences of input protection circuits. However, in a low -gain or G u003d 1 circuit, because the output of the amplifier cannot respond enough to the input slope, the fast slope input signal can beIn order to move these diode forward. Figure 31 of typical features illustrates this impact. If the input signal is fast enough to generate this positive bias condition, the input signal current must be limited to 10mA or below. If the input signal current is not restricted by in good condition, you can use the input series resistor to limit the signal input. This input series resistance reduces the low noise performance of OPA2211, and discusses the worksheet in the noise performance part of this data. FIG. 41 shows an example of a current -limiting feedback resistor.

Noise performance

FIG. 42 shows changes in the power supply source resistance of the unit gain configuration (no feedback resistance network, so there is no additional noise contribution). Total circuit noise. Two different operational amplifiers display and general circuit noise calculation. OPA2211 has a very low voltage noise, making it an ideal choice of low source impedance (less than 2K ). A similar precision computing amplifier, OPA227, has high voltage noise, but lower current noise. It provides excellent noise performance under medium source impedance (10K to 100K ). At 100K above, FET enters op amp, such as OPA132 (very low current noise) can provide better performance. The formula in FIG. 42 is used to calculate the general circuit noise. Note that EN u003d voltage noise, IN u003d current noise, RS u003d source impedance, K u003d Bolzman constant u003d 1.38 × 10–23 j/k, T is temperature (unit: K).

Basic noise calculation

The design of the low noise computing amplifier circuit needs to carefully consider various possible noise factors: noise from the signal source, in the operation amplifier The noise generated and noise from the feedback network resistor. The total noise of the circuit is a square root and combination of all noise components.

The resistance part of the source impedance generates the heat noise of proportion to the square root of the resistance. This function is shown in Figure 42. The source impedance is usually fixed; therefore, the choice of op amp and feedback resistance to minimize the contribution of their total noise.

FIG. 42 depicts the total noise of different source impedances of the op amp in the unit gain configuration (no feedback resistance network, so there is no additional noise contribution). The operation amplifier itself generates voltage noise components and current noise components. The voltage noise is usually modified as the time to change the component of the bias voltage. The current noise is modeled to the time variable in the input bias current and reacts with the source resistance to generate noise. Therefore, the minimum noise computing amplifier given by a given application depends on the source impedance. For low -source impedance, current noise can be ignored, and voltage noise usually dominates. For high -source impedance, current noise may dominate.

Explain the configuration and gain of reverse and non -inverter operation amplifiers. In ThereIn the configuration of the gain, the feedback network resistance will also produce noise. The current noise of the amplifier and the feedback resistor reaction to generate additional noise components. The feedback resistance value can usually be selected so that these noise sources can be ignored. The total noise equation of the two structures is given.

Total harmonic distortion measurement

OPA2211 series operational amplifier has excellent distortion characteristics. THD+noise is less than 0.0001%(g u003d+1, VO u003d 3VRMS) below 0.0001%(g u003d+1, VO u003d 3VRMS).

The distortion generated by the OPA2211 series operational amplifier is lower than the measurement limit of many commercial distortion analyzers. However, the special test circuit shown in China can be used to expand measurement capabilities.

Excessive electrical stress

Designers often ask the capacity of computing amplifiers to withstand excessive electrical stability. These problems are often concentrated on the device input, but may involve the power supply voltage pins and even output pins. Each different pins function has the electrical stability limit determined by the voltage breakdown characteristics of a specific semiconductor manufacturing process and a specific circuit connected to the pin. In addition, internal electrostatic discharge (ESD) is protected in these circuits to prevent an ESD incident that occurs before and in the process of product assembly.

It helps better understand the correlation between this basic ESD circuit and its electrical excessive stress events. Figure 43 shows the ESD circuit contained in OPA2211 (represented by the dotted line area). The ESD protection circuit includes several current control diode. These diode connect from the input and output pin and return to the internal power cord. There, they will be placed in the absorption device inside the operating system. This protective circuit remains inactive during the operation of the normal circuit.

The operational amplifier distortion can be considered as an internal error source, and you can refer to the input. It shows a circuit that causes 101 times the distortion of the operation amplifier than the incompetent amplifier. Adding R3 to other standards of non -mute amplifier configuration will change the feedback coefficient or noise gain of the circuit. The closed -loop gain is unchanged, but the feedback that can be used for error correction is reduced by 101 times, which increases the resolution by 101 times. Note that the input signals and loads of the computing amplifier are the same as the traditional feedback without R3. The value of R3 should be kept smaller to minimize its impact on distortion measurement.

The effectiveness of this technology can be verified by repeated measurement under high gain and/or high frequency, where the distortion is within the measurement capacity range of the test equipment. The measurement of this data table uses the dual distortion/noise analyzer of the audio precision system, which greatly simplifies repeated measurement. However, the measurement technology can be executed by manual distortion measuring instruments.

The ESD incident will generate a high -voltage pulse with a short duration. When it discharge through semiconductor devices, the pulse is convertedIt becomes a short duration and a large current. The ESD protective circuit design is used to provide a current circulation around the core of the computing amplifier to prevent it from being damaged. The energy absorbed by the protective circuit was subsequently lost in the form of heat.

When one ESD voltage is formed on the pin of two or more amplifiers, the current flows over one or more to the diode. According to the path of the current, the absorption device may be activated. The trigger voltage or threshold voltage of the absorption device is higher than the normal operating voltage of OPA2211, but it is lower than that of the breakdown voltage level of the device. Once this threshold is exceeded, the absorption device will start quickly and keep the voltage on the power rail at the level of safety.

When the operational amplifier is connected to the circuit shown in Figure 43, the ESD protection component will maintain a non -activity state and will not participate in the operation of the application circuit. However, when the external voltage exceeds the operating voltage range of the given pin, this may occur. If this happens, there are risks that some internal ESD protection circuits may be biased and transmitted. Any current is generated by guiding the diode path, rarely involved an absorption device.

FIG. 43 describes a specific example, where the input voltage Vin exceeds 500 millivolttrasion or more than 500 millivolttilow (+vs). Most of the situations in the circuit depends on the power characteristics. If+vs can absorb current, one of the upper input to the diode to guide the current to+and over -to -+with the higher and higher of the vehicle recognition number (VIN), the current level may become higher and higher. Therefore, the data table specifications are recommended to limit the input current to 10mA.

If the power supply cannot absorb the current, VIN can start to provide the current to the computing amplifier, and then take over as a positive power supply voltage source. The risk in this case is that the voltage may rise to the level that exceeds the absolute maximum rated value of the operation amplifier. In extreme but rare cases, the absorption device will be triggered when+vs and -vs. If this incident occurs, the DC path is established between+VS and -VS power. The power consumption of the absorption device is quickly exceeded, and the extreme internal heating will destroy the operational amplifier.

Another common problem is that when the power+vs and/or -vs are 0V, if the input signal is applied to the input terminal, what will happen when the amplifier will happen. Similarly, this depends on the power characteristics of the level at the level of 0V or lower than the amplitude of the input signal. If the power supply is displayed as high impedance, the power supply current of the computing amplifier can be provided by the input source through the current control. This state is not a normal partial pressure state; the amplifier is likely to not work properly. If the power impedance is low, the current to the diode may become quite high. The current level depends on the capacity of the input source transmission current and any resistance in the input path.