Features

Low noise:

4.5 kilus

10 kHz at 3.8 nv/√Hz

#8226 ; Low induction: 1 kHz is 0.00005%

Low static current: each channel 2 mia

Low input bias current: 10 PA [123 123 ]

conversion rate: 10 v/μs

width increase bandwidth: 18 mHz (g u003d+1)

unified gain stability stable

Rail transfers

wide supply range: ± 2.25 volts to ± 18 volts, or +4.5 volts to +36 volts

Double and four-heavy versions

Small packaging size: dual: SO-8 and MSOP-8, four: SO-14 and TSSOP-14

Application

Analog and digital mixer

Audio Effect Processor

Music

#8226 A/V receiver

DVD and Blu -ray #8482; Player

Auto audio system

OPA1652 (dual) and OPA1654 (4) FET input computing amplifier achieve a low of 4.5-nV/√Hz noise density, and at 1kHz, it has a 0.00005%ultra-low inconsistency. OPA1652 and OPA1654 computing amplifier provides rail-to-orbit output width within 800 millivolves, and the load is 2-k , which increases the cleanliness and expands the dynamic range to the maximum extent. These devices also have high output driving capabilities of ± 30 mAh.

These devices work within a very wide range of power range of ± 2.25 V to ± 18 V, or +4.5 V to +36 V. The power current of each channel is only 2 mA. OPA1652 and OPA1654 computing amplifier units have a stable gain, providing good dynamic performance under extensive load conditions.

These devices also have completely independent circuits to achieve the lowest string disturbances and are not affected by interaction between channels, even if they are driving or overloaded.

The temperature range of OPA1652 and OPA1654 specifies that of -40 ° C to+85 ° C.

Equipment information

(1), please refer to the appointment appendix at the end of the data table.

Typical features

Unless there are other instructions, otherwise, TA u003d 25 ° C, vs u003d ± 15 v, RL u003d 2 kΩ.

Detailed description Overview

OPA1652 and OPA1654 are a very low noise of unit gain stable, double and four lucky amplifiers. The functional frame diagram shows the simplified schematic diagram of OPA165X (displayed a channel). This device consists of a very low noise input stage with a folding conjugate grid and a rail -to -rail passing level. This topology shows superior noise and distortion performance within the extensive power voltage range that the audio amplifier did not provide in the past. Function box diagram

Function box diagram

Feature description

Inverted phase protection

OPA165X series with internal phase reversal protection protection Essence When the input is driven to the linear co -modular range, many operational amplifiers will have phase reversal. This situation is the most common in non -switching circuits. When the input is driven to the co -mode voltage range that exceeds the specified specified, the output reverse into the opposite track. The input of OPA165X can prevent the phase reversal when the co -mode voltage is too high. Instead, appropriate rail restrictions output voltage. This performance is shown in Figure 35.

Input protection

The input terminals of OPA1652 and OPA1654 use the backward direction to the diodes to prevent too high motor voltage, as shown in Figure 36. 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 enough, the fast slope input signal can make these diode move forward. If the input signal is fast enough to produce this positive bias condition, the input signal current must be limited to 10 mAh or less. If the input signal current has no inherent limit, you can use the input series resistor (RI) and/or feedback resistor (RF) to limit the signal input current. The resistor reduces the low noise performance of OPA165X and is checked in the following noise performance part. Figure 36 shows the configuration example when using a current limit input and feedback resistance.

Electrical stress

DesignThose often ask the capacity of the computing amplifier to withstand excessive electrical stress. These problems are often concentrated on the device input end, but it may also involve the power supply voltage pins, and even the output end pin. 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 is helpful to understand this basic ESD circuit and its correlation with electrical excessive stress events. Figure 37 shows the ESD circuit contained in OPA165X (represented by the dotted line area). The ESD protection circuit includes several current control diode. These diode connect from the input and output pins and return to the internal power cord. The diode will meet the absorption device of the inside of the operation amplifier. The protective circuit aims to maintain a non -activity state during normal circuit operation.

The ESD event will generate high -voltage pulses with short duration. When discharge through semiconductor devices, the pulse will be converted into large -current pulse with short duration. The ESD protection circuit design provides a current circulation around the core of the computing amplifier to prevent damage. The energy absorbed by the protective circuit was subsequently lost in the form of heat.

When the ESD voltage is formed on two or more amplifier equipment pins, the current flows over one or more to the diode. According to the current path, the absorption device can be activated. The trigger voltage or threshold voltage of the absorption device is higher than the normal operating voltage of OPA165X, but it is lower than that of the breakdown voltage level of the device. When this threshold is exceeded, the absorption device will quickly start, and the voltage on the power rail will be stabbed to the safe level.

When the operational amplifier is connected to the circuit (see Figure 37), 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 is a risk of some internal ESD protection circuits that turn on and transmit current. Any current is generated by guiding the diode path, rarely involved an absorption device.

FIG. 37 shows a specific example, where the input voltage (VIN) exceeds 500 millivoltors (V+) 500 millivol to more. Most of the situations in the circuit depends on the power characteristics. If V+can absorb the current, the upper input is turned into one in the diode to guide and guide to V+. Excessive current levels flow as the vehicle recognition number (VIN) is getting higher and higher. Therefore, the data table specifications are recommended to limit the input current to 10 mAh.

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 exceeding the operation amplifierAbsolutely maximum rated level.

Another common problem is that when the power supply (V+or V-) is 0 V, if the input signal is applied to the input, what will happen to the amplifier. Similarly, this problem depends on the power characteristics, when the power supply voltage is 0 V or lower than the input signal amplitude. If the power supply is displayed as high impedance, the input source provides an operational amplifier current through the current control the diode. This state is not a normal partial pressure; it is likely that the amplifier cannot work normally. 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.

If there is any uncertainty of the power absorption current, please add an external Qina diode to the power pins; see Figure 37. Choose Qina voltage so that the diode will not be turned on during normal operation. However, Qina's voltage must be low enough to turn on the Qina diode when the power pins start to rise to the level of safety work voltage level.

Equipment function mode

Working voltage

OPA165X series operational amplifier work in the range of the voltage range of the power supply range of ± 2.25 volt to ± 18 volts, while maintaining excellent performance. The OPA165X series can work when the voltage of the power supply is+4.5V, and the voltage of the power supply is+36V. However, some applications do not require the same positive and negative output voltage. For the OPA165X series, the power supply voltage does not need to be equal. For example, the positive power supply can be set to +25 V, and the negative power supply is set to -5 V.

In all cases, the co -mode voltage must be kept within the specified range. In addition, the key parameters are guaranteed within the specified temperature range from TA u003d -40 ° C to+85 ° C. The typical feature shows the parameters of significantly changes with the working voltage or temperature.

Application and implementation

Note: The information in the following application chapters is not part of the TI component specification, TI does not guarantee its accuracy or integrity. TI's customers are responsible for determining the applicability of the component. Customers should verify and test their design implementation to confirm the system function.

Application information

Noise performance

FIG General circuit noise of impedance changes.

OPA165X (GBW u003d 18 MHz, G u003d+1) is displayed, and the general circuit noise is calculated. The computing amplifier itself provides voltage noise components and current noise components. Voltage noise is usually modified as a part of the bias voltage. The current noise is modeled to the time variable in the input bias current, and the voltage component of the noise is generated with the source resistance reaction. Therefore, the minimum noise computing amplifier of the given application depends on the source impedance. Low sourceUns related, current noise can be ignored, and voltage noise usually dominates. The voltage noise of the OPA165X series operational amplifier makes it a better choice of source impedance greater than or or equal to 1K

Formula in FIG. 38 shows the calculation of the general circuit noise. These parameters are as follows:

EN u003d voltage noise

in u003d current噪声

RSu003d源阻抗

ku003d玻尔兹曼常数u003d

Tu003d温度， Unit: Kaishi (K)

The design of the low noise computing amplifier circuit needs to carefully consider various possible noise factors: noise from the signal source, the generated amplifier produced in the operation amplifier generated Noise and noise from feedback network resistors. 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. Figure 38 depicts this equation. The source impedance is usually fixed; therefore, the choice of op amp and feedback resistance to minimize the contribution of their total noise.

FIG. 39 illustrates the configuration of the inverter (Figure 39B) and the non -inverter (Figure 39A) computing amplifier circuit configuration. In the configuration of the gains, 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

OPA165X series operational amplifier has excellent distortion characteristics. In the audio range of 20 Hz to 20 kunhe, THD+noise is less than 0.0002%(g u003d+1, VO u003d 3 VRMS, BW u003d 80 kHz) (see Features Figure 7).

The distortion generated by the OPA165X series operational amplifier is lower than the measurement limit of many commercial distortion analyzers. However, special test circuits (as shown in Figure 40) can be used to expand the measurement capabilities.

The operational amplifier distortion can be considered as an internal error source, and you can refer to the input. FIG. 40 shows the circuit that causes the increasing increasing distortion of the computing amplifier (the distortion gain factor of various signal gain, please refer to the form in Figure 40). 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 distorted gain factors, thereby increasing the same amount of resolution. Note that the input signal and load of the application to the computing amplifier are the same as the traditional feedback without R3. R3 valueKeep it 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.

(1), please refer to Figure 7 to Figure 12.

The dynamic characteristics of capacitance load

OPA1652 and OPA1654 have been optimized for common gain, load and operating conditions. The binding of low -closed cycle gains and high -inclusive loads reduces the phase margin of the amplifier and may lead to peak or oscillation of gain. Therefore, the heavier capacitance load must be isolated from the output. The easiest way to achieve this isolation is to connect a small resistance (eg, RS is equal to 50Ω) at the output end.

This small series resistance can also prevent excessive power consumption, if the output of the device is shorter.

FIG. 19 shows the relationship diagram of the small signal super -adjustment and capacitance load of several RS values. In addition, for the detailed information about analytical technology and application circuits, please refer to the feedback diagram DEFINEOPACEPERFRORMANCE (SBOA015), you can download it from the Ti website.

Typical application

The choice of 16 operations amplifiers made it an excellent audio computing amplifier. One of these circuits is shown in Figure 41, which illustrates the power amplifier circuit suitable for high -fidelity headset applications.

Design requirements

gain: 6 db

output voltage: gt; 2 vRMS, 32Ω Load

Output impedance: lt; 1Ω

Thd+N: LT (1 kHz, 2 VRMS, 32Ω load)

] Detailed design program

Power amplifier circuit (displayed by single channels) has a BUF634 high -speed buffer amplifier in the feedback circuit of OPA1652 to increase the available output current. BUF634's bandwidth and power consumption can be set through the external resistor RBW. In this circuit, RBW uses a 0Ω resistor to make the BUF634 have the widest bandwidth and the highest performance. The gain of the circuit is determined by the feedback resistor R1 and R2, as shown in the equal form 1:

) The design goals, the values u200bu200bof R1 and R2 must be equal. These resistors also generate noise and thermal noise to the circuit. The voltage noise spectrum density of the feedback resistor (refer to the amplifier input) such as the equal form:

In ideal, the thermal noise contribution of the resistance will not significantly reduce the circuit's circuit Noise performance. Select the resistance value to make the resistance noise less than one -third of the input voltage noise (Formula 3) of the input voltage noise of the computing amplifier, which can ensure that any increase in the circuit noise caused by the contribution of the feedback resistance can be minimized.

In order to calculate the required resistance value, the Formula 3 is inserted into Formula 2, and the proceeds are reorganized to solve the parallel combination of R1 and R2, as shown in Formula Essence The combination of the NVA value R1.6Ω/16Ω is combined with the voltage value of 16.8Ω. R1 and R2 use a resistor with a standard value of 200Ω to get a parallel value of 100Ω, which is very close to the required value.

Due to the extremely broad band width and high conversion rate of BUF634, no additional components are required to maintain the stability of the circuit or prevent atresia. The circuit is stable when the capacitor load is greater than 1NF, suitable for headset applications.

Application curve

The measurement performance of the circuit is shown in Figure 42 to 46. The frequency response is very flat in the entire audio bandwidth, only 0.004 dB within the scope of hearing. The decrease in gain display at low frequency is the result of the test equipment, not the amplifier circuit. The amplifier output impedance calculated based on the change of gain under load and empty load conditions is 0.036Ω. The maximum output before shearing is shown in Figure 43. For a 32Ω load, the power amplifier can provide 781 MW before cutting waves. When the load is 32Ω, the best THD+N performance is -117.2DB at 678MW (1kHz, 22kHz measurement bandwidth). FIG. 44 shows the relationship between THD+N and frequency measured in the 2-VRMS output level measured in the 90 kHz bandwidth. The measured value in the worst case is 16Ω load (250 mW), 20 kHz input frequency, and –91.8 dB (0.0026%). Two FFTs also show 2-vRMS, 1-kHz, and basically to two different load amplifiers output spectrum. Under two load conditions, all distortion harmonics are lower than -120 dB compared to the base wave.

OPA165X regulations under the conditions of 4.5 v to 36 v (± 2.25 v to ± 18 v); many specifications It is suitable for -40 ° C to+85 ° C. Parameters related to work voltage or temperature are given in the typical feature part. Noise or high impedance electricityThe application of the source requires an outdated capacitor near the device pins. In most cases, 0.1-μF capacitors are enough.

Layout

layout guide

In order to obtain the best operating performance of the equipment, please use good printing circuit board (PCB) layout practice, including: [123 123 ]

noise can be transmitted to the simulation circuit through the power pins of the entire circuit and the op amp itself. The barrier container is used to reduce the coupling noise by providing a low -impedance power supply of an analog circuit.

-Colin the low ESR and 0.1-μF ceramic side electric container between each power supply foot and ground, and as close to the device as much as possible. Single -width capacitors from V+to the ground are suitable for single power applications.

Circuit simulation and the individual grounding of the digital part are one of the simplest and most effective noise suppression methods. A layer or multi -layer on the multi -layer printing circuit board is usually used for ground layers. The ground layer helps to distribute heat and reduce the noise pickup of electromagnetic interference (EMI). Physical separation numbers and simulation ground, observe the flow of ground current.

In order to reduce parasitic coupling, the input trajectory should be as far away from the power supply or output trajectory as much as possible. If these record channels cannot be separated, it is much better than parallel to the noise recorder.

The external components are as close to the device as possible. As shown in Figure 47, keeping RF and RG approaching inverter inputs can minimize parasitic capacitors.

The length of the input record should be as short as possible. Always remember that the input trajectory is the most sensitive part of the circuit.

Consider setting a driver's low impedance protection ring around the key line. The protective ring can significantly reduce the leakage current of different potentials nearby.

It is recommended to clean the PCB after assembly to obtain the best performance.

Any precision set circuit may change performance changes due to water entering plastic packaging. After any water -based PCB cleaning process, it is recommended to bake PCB components to remove the water packaging water during the cleaning process. In most cases, it is enough to clean and bake after low temperature at 85 ° C.

layout example

Power consumption

OPA1652 and OPA1654 series operations amplifier ± 18 V, the working temperature range is complete. When working at a high power supply voltage, the internal power consumption increases. Compared with traditional materials, the copper quotation frame structure used by the OPA165X series operations amplifier improves heat dissipation. The circuit board layout also helps the maximum limitReduce the temperature rise.Wide copper traces help heat dissipation as an extra radiator.By welding the device to the circuit board instead of using the socket, the temperature can be further raised to the lowest.