Features

Suitable for car applications

AEC-Q100 to meet the following results:

-Equipment temperature level 1: --40 ° C To+125 ° C The temperature range of the environment

- Equipment HBM ESD level 2

- Device CDM ESD classification level C4B

Low static current (IQ) (IQ) : 45 μA (typical value)

Low cost

Rail -to -track input and output

Single power supply: 2.1 v 5.5 v

Input bias current: 0.5 PA (typical value)

High -speed: Power Bandwidth: 1 MHz

Application

portable equipment

battery power supply equipment

smoke alarm

]

HEV/EV and Power Transmission Department

Information entertainment and cluster

Medical Device

Instructions

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OPAX348-Q1 series device is a single power supply, a low-power CMOS operational amplifier. OPAX348-Q1 series equipment has a 1MHz expansion bandwidth and 45μA power current, which is suitable for low-power applications from 2.1V to 5.5V.

The low power current of 45μA and the input bias current of 0.5 PA make the OPAX348-Q1 series device the best candidate product for low power consumption, high impedance applications (such as smoke detectors and other sensors).

OPA348-Q1 devices include SOT23-5 (DBV) and SOIC (D). OPA2348-Q1 device is encapsulated by SOIC-8 (d). OPA4348-Q1 device is provided in the Tssop-14 (PW) package. The temperature range of the car under all power supply voltage is -40 ° C to+125 ° C, which provides additional design flexibility.

Equipment information

(1), please refer to the appointment of the doctor's order content at the end of the data table.

No reversal configuration driver ADS7822

Typical features

At TA u003d 25 ° C, RL u003d 100 K Connect to vs/2, vout u003d vs/2 (unless there is another instructions).

Detailed instruction It is a low -power consumption, rail -to -orbit input and output computing amplifier. The working voltage of these devices is from 1.8 to 5.5 volts, and the unit gain is stable, which is suitable for extensive common applications. The AB-level output level can drive the ≤10-kΩ load between any points between V+and the ground. The input co-mode voltage range includes two orbits, and allows the OPAX348-Q1 series device to apply for almost any single power supply. Rail -to -rail input and output vessels have greatly increased the dynamic range, especially in low power applications, making it an ideal choice for driving sampling modulus converter (ADC). Function box diagram

Feature description

Work voltage

OPAX348-Q1 operation amplifier fully meets the requirements. 1.8 V to 5.5 V working within the voltage range. In addition, many specifications are suitable for between -40 ° C to+125 ° C. The parameters that significantly change with the working voltage or temperature are shown in the typical characteristic diagram. The power pins should be bypass with 0.01-μF ceramic capacitors.

Rail -to -rail input

Extended the input voltage range of OPAX3200MV to the input voltage range of the OPAX3200 series. This performance is achieved through a complementary input level: a N channel input difference is parallel parallel with a P channel differential. The N channel is effective for the input voltage near the positive orbit, usually above the positive power supply (V+)-1.3 V to 200 mv. For inputs from 200 MV below the negative power supply to about (V+)-1.3 V, the P channel is in the open state. There is a small transition area, which is usually (V+) -1.4 V to (V+)-1.2 V, which are both pairs of pairs. This 200 millival transition zone can change to 300 millivolves as the process changes. Therefore, at the low-end, the range of the transition zone (both stages) is (V+)-1.7 V to (V+)-1.5 V, and high-end (V+) -1.1 V to (V+)-0.9 V. In this transition area, PSRR, CMRR, offset voltage, offset drift and THD may be reduced compared with the operation of the device outside the area.

Rail-to-rail input

Enter the extension of the consensus range from (V-)-0.2 V to (V+)+0.2 V. For normal operation, input should be limited to this rangeInside. The absolute maximum input voltage exceeds 500 millivolves. Although the input of the input co -mode but less than the maximum input voltage is invalid, it will not cause any damage to the calculator. Unlike other computing amplifiers, if the input current is limited, the input may exceed the power supply without a phase reversal, as shown in Figure 19.

Under normal circumstances, the input current is 0.5 PA. However, large input (over 500 MV) can cause excess current flow or outflow input pins. Therefore, it is important to limit the input current to less than 10 mAh and keep the input voltage below the maximum rated value. As shown in Figure 20, the input resistance is easy to achieve.

Input and ESD protection

OPAX348-Q1 series device integrates internal electrostatic discharge (ESD) protection circuits on all pins. For input and output pins, this protection is mainly composed of a current -controlled diode connected between input and power pins. These ESD protection diodes also provide input -drive protection in the circuit, as long as the current is limited to 10 mAh, as described as an absolutely maximum rated value table. FIG. 21 shows how to add a series input resistance to the driver input to limit the input current. The increased resistance generates thermal noise at the amplifier input terminal, and in the application of sensitivity to noise, the value should be kept at the minimum value.

Common-modal suppression ratio (CMRR)

OPAX348-Q1 series device CMRR has multiple regulations, so it can be used to use the most matched application of the given application. CMRR; see electrical feature tables. First of all, the transition area [VCM LT; (V+) -1.3V] below the CMRR within the common modular range. When the application needs to use a differential input pair, this specification is the best indicator of the equipment performance. Secondly, the co -model suppression ratio of the entire co -model range is (VCM u003d - 0.2 V to 5.7 V). The last value includes changes seen through the transition area (see Figure 22).

Common mode voltage range

The input co-mode voltage range of the OPAX348-Q1 device exceeds 200 millivolves of the power rail. The scope of this extension is achieved through a complementary input level of an N channel input differential pair with a P channel differential parallel. For the input voltage near the track, the N channel is valid, usually above the (V+)-1.2 V to 300 MV above the positive pole power, and the P channel is to about 300 MV below the negative power to about (V+)-1.4 V. The input voltage is turned on. There is a small transition zone, usually (V+) -1.4 V to (V+) -1.2 V. The two voltage pairs are open in this transition area. The 200 MV transition zone shown in FIG. 22 can change ± 300 MV with the process. Therefore, at the low end,The range of the transition zone (both in both stages) is (V+) -1.7 V to (V+)-1.5 V, high-end (V+)-1.1 V to (V+)-0.9 V. In the 200MV transition zone, PSRR, CMRR, offset voltage, offset drift and THD may be reduced compared with the operation outside the area.

Electromagnetic interference sensitivity and input filtering

The computing amplifier changes with the sensitivity of electromagnetic interference (EMI). If the transmission EMI enters the computing amplifier, when the EMI exists, the DC offset observed by the amplifier output place may deviate from the nominal value. This offset is the result of the rectification of signal related to internal semiconductor knots. Although all operational amplifiers pin function will be affected by electromagnetic interference, the signal input pin may be the most vulnerable. OPAX348-Q1 series device contains an internal input low-pass filter to reduce the response of the amplifier to EMI. The filter provides co -mode and differential filtering. The cut-off frequency of this filter is about 80MHz (-3DB), and at an attenuation of 20DB every ten years.

Texas Instrument Company has developed an antipity on the broadband zone that can accurately measure and quantitative operational amplifier at a broadband zone from 10 MM to 6 MM. EMI inhibitory ratio (EMIRR) indicator allows direct comparative comparative amplifiers through EMI antidity. Details can also be found in the application report, and the EMI suppression ratio of the operation amplifier (SBOA128).

Output

As a micro-power, low noise computing amplifier, the OPAX348-Q1 series device provides a strong output drive capability. The AB output stage adopts a common source transistor to achieve a complete rail -to -orbit output swing capacity. For the resistance load of up to 10 kΩ, regardless of the power supply voltage, the output is usually swinging within the 5 MV range of any power rail. Different load conditions will change the capacity of the amplifier near the track swing; the reference diagram, output voltage swing and output current.

Class AB output level adopts a common source transistor to achieve rail transition. The output level can drive 5-k loads between any potential between V+and ground. For light resistance loads ( gt; 100k ), the output voltage can usually swing from the power rail to 18mv. In the case of medium resistance load (10 k to 50 k ), the output voltage can usually swing in the range of 100 MVs of the power rail, while maintaining a high open loop gain (see the graph in the typical feature part 6).

Capacity load and stability

OPAX348-Q1 series devices configured in unit gains can directly drive up to 250PF pure capacitor load. Increase gainIn order to enhance the capacity of the amplifier to drive a larger capacitance load (see Figure 13 of the typical feature part). In the unit gain configuration, the capacitance load driver can be improved by connecting a small (10Ω to 20Ω) resistor RS at the output end, as shown in Figure 24. This resistor significantly reduces the bell while maintaining the DC performance of pure capacitance load. However, if the resistance load and the capacitance load are connected parallel, the division will be generated, the DC (DC) error is introduced at the output end, and the output swing is slightly reduced. The introduction of error and ratio RS/RL is proportional, and it can usually be ignored.

In the configuration of the unit gain inverter, the phase margin can be reduced by the capacitor and the gain setting of the resistance at the capacity of the amplifier input terminal, thereby reducing the capacitance Load driver. The best performance can be obtained by using small value resistors. For example, when driving 500 PF loads, the resistance value is reduced from 100 k reduced to 5 k reduced over 55%to 13%(see Figure 13 of the typical feature part). However, when a large value resistance cannot be avoided, a small (4-PF to 6-PF) capacitor CFB can be inserted in the feedback circuit, as shown in Figure 25. This small capacitor has a significant reduction in the impact of compensating capacitor CIN (including the input capacitance of the amplifier and the parasitic capacitor of the printing circuit board (PCB)).

Equipment function mode

After connecting the power supply, the OPAX348-Q1 series device is powered on. This device can run as a single power computing amplifier or dual -power amplifier, depending on the application.

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

OPAX348-Q1 operation amplifier (operation amplifier) u200bu200bunits are stable and suitable for extensive universal applications.

OPAX348-Q1 device has broad bandwidth width and unit gain stability, with rail-to-rail input and output to increase the dynamic range. Figure 23 shows the input and output waveforms of the OPAX348-Q1 device configured by UnityGain. The operation is powered by a single 5 V power supply, and the load is connected to VS/2. The input is 5-VPP sine waves. The output voltage is about 4.98 VPP.

Power insertion should be bypassed with 0.01-μF ceramic capacitors.

Drive Mo Digital Converter (ADC)

OPAX348-Q1 operation amplifierIt is used to drive medium -speed sampling ADC. OPAX348-Q1 The operational amplifier buffer the ADC input capacitance while providing a signal gain and a contributed charge generated.

FIG. 26 shows OPA2348 in the basic non -conversion configuration of the drive ADS7822 device. The ADS7822 device is a 12-bit micro-power sampling converter in the MSOP-8 package. When used with the low-power micro-packaging of OPAX348-Q1 series devices, this combination is an ideal choice for limited space and low power applications. In this configuration, the RC network of the ADC input terminal can be used to provide anti -hybrid filtering and charge injection current.

OPAX348-Q1 series device can also be used for non-conversion configuration, driving ADS7822 devices in a limited low power consumption application. In this configuration, the RC network of the ADC input terminal can be used to provide anti -hybrid filtering and charge injection current. The OPAX348-Q1 of the ADS7822 device in the voice belt filter data collection system is shown in Figure 26. This small, low -cost solution provides necessary amplification and signal regulation to directly connect to the polar microphone interface. This circuit works under the conditions of VS u003d 2.7 V to 5 V, and the typical static current is less than 250 μA.

Typical application

Some applications require differential signals. Figure 28 shows a simple circuit that converts the single -end input of 0.1 V to 2.4 V to the ± 2.3 V differential output on a single 2.7 V power supply. Interesting to limit the output range to maximize lineivity. The circuit consists of two amplifiers. A amplifier has a buffer effect to generate voltage VOUT+. The second amplifier inputs and adds a reference voltage to generate Vout -. VOUT+and VOUT -range from 0.1 V to 2.4 V. Value VDiff is the difference between Vout+and Vout -. This configuration makes the differential output voltage range of 2.3V.

Design requirements

The design requirements are as follows:

Power supply voltage: 2.7 v

# 8226; Reference voltage: 2.5 v

Input: 0.1 V to 2.4 v

output slump: ± 2.3 v

Output co -mode voltage: 1.25 v

Small signal bandwidth: 1 MHz

Detailed design program

The circuit receiving single -end input signal vin in FIG. 28, And generate two output signals VOUT+and VOUT -Use two amplifiers and a reference voltage VREF. VOUT+is the output of the first amplifier, which is the buffer version of the input signal VIN (such as the equal form 1). Vout -is the output of the second amplifier. It uses VREF to add offset voltage to VIN and add reverse gains by feedback. The transmission function of VOUT - is given in Formula 2.

Differential output signal VDIFF is two single-end output signals Vout+and Vout-. Formula 3 shows the transmission function of the VDiff. By applying the conditions of R1 u003d R2 and R3 u003d R4, the transmission function is simplified to equation 6. With this configuration, the maximum input signal is equal to the reference voltage, and the maximum output of each amplifier is equal to VREF. Differential output range is 2 × VREF. In addition, the co -mode voltage (VCM) is half of VREF (see equations 7).

The amplifier selection

The linearity within the input range is the key to good DC accuracy. The limit of the input range and output of the co -mode determines linearity. Generally speaking, a amplifier with rail -orbit input and output swing is needed. Bandwidth is a key issue of this design. Therefore, choosing the OPAX348-Q1 series device is because its bandwidth is greater than 1MHz. The bandwidth and power compare to the high power efficiency of the device, and the low offset and drift ensure the good accuracy of the middle accuracy.

无源元件选择

由于VOUT的传递函数严重依赖于电阻器（R1、R2、R3和R4），因此使用低公差的电阻器可最大限度地提高性能并Minimize the error. This design uses a resistor with a resistance of 49.9 kΩ and a tolerance of 0.1%. However, if the noise of the system is a key parameter, you can choose a smaller resistance (6kΩ or lower) to maintain the low noise of the entire system. This technology ensures that the noise from the resistor is lower than the noise of the amplifier.

Application curve

Power suggestion

OPAX348-Q1 series device specifications V) work; many specifications are suitable for -40 ° C to 125 ° C. The parameters of typical features may show a significant difference in working voltage or temperature.

Pay attention to safety

The absolute voltage is greater than 7 V (can be permanently damaged device).

The 0.1-μF bypass electric container closer to the power supply foot to reduce the coupling error of noise or high impedance power supply. For more details on the placement of the side electric container, please refer to the layout guide.

Layout

Layout Guide

In order to obtain the best operating performance of the equipment, please use good PCB layout practice, including:

noise can pass the power pins and operational amplifiers through the entire circuit's power pins and operational amplifiers Propaganda to analog circuit. The bypass capacitors reduce the coupling noise by providing local low impedance power supplies for the simulation 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 floor helps to distribute heat and reduce the noise of electromagnetic interference. Ensure that the number of numbers and simulation of the ground is separated, and the flowing current flows. For details, see the circuit board layout technology, Sloa089.

stay away from the parasite line of input or output as much as possible. If these traces cannot be separated, the vertical trace line is much better than the noise trace line.

The external components are as close to the device as possible. Keep RF and RG approach the inverter input and minimize parasitic capacitors, as shown in Figure 32.

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.

layout example