Features

Single power operation: 2.7 V to 12 V

Wide input voltage range

Output swing between the rail

current 300 μA/300μA [ 123]

Broadband: 3 MHz

conversion rate: 0.5V/μs

Low -dimensional voltage: 700 μV

No phase reversal

Application

Industrial process control

Battery power supply instrument

Power control and protection

Remote sensor

Low -voltage low voltage Shocked film amplifier

DAC output amplifier

General description

OP191

,

OP291

, OP491 Yes, yes Single, double and four -micro power, single power supply, 3MHz bandwidth bandwidth, with rail -to -rail input and output. All power supply is guaranteed to run under the +3 V single power supply and ± 5 V dual power supply. The OPX91 series manufactured in the simulation device CBCMOS process has a unique input stage that allows the input voltage to be expanded to above 10V without any phase reversal or atresia. The output voltage fluctuates within the millivolo range of the power supply and continues to supply the current to the power supply. The applications of these amplifies include portable telecommunications equipment, power control and protection, and wide output range sensors. The sensor of the rail -to -orbit input amplifier includes Hall effect, piezoelectric and resistor.

The ability of the input and output rail enables the designer to build a multi -stage filter in the single power system and maintain a high signal -to -noise ratio.

OP191/OP291/OP491 is specified within the extended industrial -40 ° C to+125 ° C temperature range. The OP191 single -placeder and OP291 dual amplifier use 8 -lead plastic SOIC surface installation and packaging. The OP491 four -line group has 14 -line PDIP, 14 -line narrow SOIC packaging and 14 -line Tssop.

pin configuration

Absolute maximum rated value

more than absolute maximum rated stress stress It may cause permanent damage to the device. This is just a stress rated value; it does not imply that the device's functional operations described in the operation part of this specification or any other conditions. Long -term exposure to absolute maximum rated conditions may affect the reliability of the device.

Absolutely maximum rated value is suitable for dice and packaging parts, unless there is another instructions.

Thermal resistance

θja is used in the worst case; that is, θja is specified for the device in the socket encapsulated by the PDIP; θja is specified for the welded device welded in the circuit board in Tssop and SOIC.

Typical performance features

]

Operation Theory

OP191/OP291/OP491 is a single power supply , Micro -power amplifier, with rail pairing input and output. In order to achieve wide input and output range, these amplifiers use unique input and output levels. In FIG. 61, the input level includes two differential pairs, a PNP pair with an NPN pair. These two stages do not work in parallel. Instead, only one level is in the open state for any given input signal level. PNP grade (transistor Q1 and transistor Q2) are required to ensure that when the input voltage is approaching and reaches the negative, the amplifier will keep the linear area. On the other hand, NPN (crystal tube Q5 and transistor Q6) need to be reached or included in orbit.

For most input co -mode range, the PNP phase is activity, as shown in Figure 12. Please note that the bias current is about 1.2 V to 1.3 V below the right track. When the voltage is lower than this value, the partial voltage current flows out of OP291 and indicates the PNP input level. However, exceeding this voltage, the bias current enters the device, showing the NPN stage. The actual institutions used in the amplifier to switch between the input level include the transistor Q3, the transistor Q4, and the crystal tube Q7. As the input co -mode voltage increases, the launch pole of Q1 and Q2 follows the voltage plus the decrease of the diode. In the end, the launch of Q1 and Q2 is extremely high enough to open Q3, so that the tail flow of 8 μA is transferred from the PNP input level to turn off it. Instead, the current via Q4 and Q7 mirrors to activate the NPN input level.

Note that the input level includes a 5KΩ series resistance and differential diode. This is a common method in the bipolar amplifier to protect the input transistor's non -large differential voltage. When the differential voltage exceeds about 0.6 V, these diode will open. In this case, the current flows between the input pins and is only limited by the two 5 kΩ resistors. This characteristic is important in the circuit where the amplifier can open the loop, such as the comparator. Evaluate each circuit carefully to ensure that the current increase will not affect performance.

Like most output levels, the output stage in the OP191 device uses PNP and NPN transistors; Rail -to -rail output swingEssence When the output voltage is close to positive and negative, these transistors begin to be saturated. Therefore, the ultimate limit of the output voltage is the saturated voltage of these transistors, about 50 millivoltors. The output level has an inherent gain generated by a set (a set of electrode and any external load impedance. Therefore, the opening gain of the amplifier depends on the load resistance.

Enter overvoltage protection

Like any semiconductor device, as long as there is a condition that inputs exceeds any power voltage, check the input overvoltage characteristics. When a voltage occurs, the amplifier may be damaged, depending on the voltage level and the size of the fault current. Figure 62 shows the characteristics of the OP191 series. The diagram is generated from the curve tracker from the ground power and connected to the input terminal. When the input voltage exceeds the power supply exceeds 0.6 volts, the internal PN is connected to the power, and the allowable current allows the current from the input to the power supply. As mentioned earlier, OP291/OP491 does have 5 KΩ resistors to connect series with each input to help limit the current. By calculating the slope of the current and voltage in the calculation diagram, the 5 kΩ resistor can be determined.

As long as the input current is limited to 5 mAh or less, the input current does not cause inherent damage to the device. For the input of 10 V on the power supply, the current limit is 1.8 mA. If the voltage is large enough and the current exceeds 5 mAh, an external series resistor should be added. The maximum overvoltage is divided by 5 mA, and the internal 5 kΩ resistor is reduced to calculate the size of the resistor. For example, if the input voltage can reach 100 V, the external resistance should be (100 V/5 mA) u0026#8722; 5 kΩ u003d 15 kΩ. If the input is affected by overvoltage, the resistance should be connected in series with one or two inputs.

The output voltage phase reversal

Some operational amplifiers designed for the work of the single power supply. When the input is driven by the effective common modulus range, the output voltage phase reverse will appear. Generally, for the single -power bilateral operational amplifier, the negative power source determines the lower limit of the scope of the co -mode. Among these devices, the anode grounding and cathode -connected external clamping diode can prevent the input signal from shifting the negative power supply (ie GND) of the device, thereby preventing the situation that may cause the output voltage to change the phase. The JFET input amplifier can also display the phase reversal. If so, a series of input resistance is usually required to prevent it.

Due to its novel input structure, OP191 does not have a reasonable input voltage range limit. In fact, the input signal can exceed a large part of the power supply voltage without damage to the device. As shown in Figure 64, the OP191 series can securely process the 20 V P-P input signal on the ± 5 V power supply without showing signs of any output voltage phase reversal or other abnormal behaviors. Therefore, no external clamping diode is required.

Specific recovery

Excessive recovery of the operation amplifier is the time required for the output voltage from saturated to its linear area. This recovery time is important in the application that the amplifier must quickly recover after a large transient event, such as comparator. The circuit shown in FIG. 63 is used to evaluate OPX91 over driving recovery time. OPX91 recovers about 8 μs from positive saturation, and recovered from negative saturation about 6.5 μs.

Single 3V power supply, instrument amplifier

OP291's low power current and low voltage operations make it a battery battery The ideal choice of power supply application, as shown in Figure 65. The circuit adopts the classic dual -transportation instrument outdoor topology, and the gain is set with four resistors. This equation is just an irreversible equation, as shown in Figure 65. Two resistors marked with R1 and the two resistors that marked as R2 should be closely matched to ensure good co -mode inhibitory performance. The resistance network ensures the closest matching and matching drift to obtain good temperature stability. Including capacitor C1 to limit bandwidth, thereby limiting noise in sensitive applications. The value of the capacitor should be adjusted according to the closed loop bandwidth required by the instrument amplifier. The RC combination generates a pole at a frequency of 1/(2π × R1C1). If AC-CMRR is a critical value, the matching capacitor of C1 should be included on the second resistor marked as R1.

Due to OP291 receiving rail pairing input, the input co -modular range includes the positive power supply of ground and 3V. In addition, the rail -to -orbit output range ensures the wider signal range as much as possible, and maximizes the system's dynamic range. In addition, due to its low power current of 300 μA/device, the circuit consumes only a static current of 600 μA, but it still has a 3MHz gain bandwidth.

There may be problems with other instrument amplifiers of single power applications. For example, the change of this topology increases the fifth resistance between the two reverse inputs of the computing amplifier set up in gain settings. Although this topological structure works well in dual power applications, it is not suitable for single power circuits. The same is true for the traditional three -handed instrument amplifier. In these two cases, the circuit cannot work in the case of a single power, unless the power is generated between the power supply.

Single power supply resistance temperature detector amplifier

The circuit in FIG. 66 uses the three operations amplifiers of OP491 to develop a bridge configuration of an RTD amplifier. The amplifier is powered by a 5V power supply. The circuit uses OP491 wide output to generate a high -bridge excitation voltage with a 3.9 V. In fact, due to rail -to -orbit output width, the circuit is used as low as 4.0 V power. The amplifier A1 servo bridge, together with AD589 to generate a constant excitation current, 1.235V precision benchmark.The computing amplifier maintains the reference voltage through parallel combinations of 6.19 kΩ and 2.55 MΩ resistors to generate a 200μA current source. The current is uniformly diverted and flows through the two -half part of the bridge. Therefore, 100 μA flows the RTD and generates output voltage according to the resistance. 3 wire resistor temperature detector is used to balance the line resistance of two 100Ω pillars of the bridge to improve the accuracy.

The amplifier A2 and the amplifier A3 are configured in the dual -transport instrument amplifier topology described in the single 3V power instrument amplifier part. Selecting a resistor can generate a 274 gain. As the temperature increases by 1 ° C, the output voltage will change 10 MV changes to facilitate measurement. The 100kΩ resistor on the amplifier A3 connects a 0.01 μF capacitor to filter out any unnecessary noise from the high -gain circuit. This special RC combination generates 1.6 kHz.

2.5 V reference voltage from 3 V power

In many single power supply applications, 2.5 V reference voltage often needs to be required. Many commercial single -piece 2.5 V reference voltage requires the minimum working power supply voltage to 4 V. When the minimum operating system has a power supply voltage of 3 V, the problem is even more serious. The circuit shown in FIG. 67 is an example of a 2.5 V reference voltage. The reference voltage is powered by a single 3 V power supply. The circuit uses the OP291 rail input and output voltage range to amplify the AD589 1.235V output to 2.5V. 1 μV/° C OP291 low TCVOS helps maintain the output voltage temperature coefficient of less than 200 ppm/° C. The overall temperature coefficient of the circuit is controlled by the temperature coefficients of R2 and R3. It is recommended to use a resistor with a lower temperature coefficient. The current of the entire circuit at a 3V power at 25 ° C is less than 420 μA.

Only 5V, 12 -bit DAC rail swing

OPX91 series is very suitable for use with CMOS DAC to produce digital control with a wide output range Voltage. Figure 68 shows the DAC8043 used with AD589 to generate voltage output from 0 V to 1.23 V. DAC works in the voltage switch mode, of which the benchmark is connected to the current output iOUT, and the output voltage is taken from the VREF pin. Contrary to the traditional current output mode, this topology is essentially irreversible, so it is not suitable for single power supply.

OP291 has two functions. First, the high output impedance of the DAC VREF pin needs to be buffered, about 10 kΩ. The computing amplifier provides low impedance output to drive any follow -up circuit. Secondly, the operational amplifier amplifier output signal is provided to provide rail pairing output swing. In this special case, the gain is set to 4.1 to generate 5.0V output when DAC is fully standard. likeIf the result requires other output voltage range, such as 0 V to 4.095 V, you can easily adjust the gain by changing the value of the resistor.

High -voltage side current monitor

In the design of the power control circuit, a large number of design work is concentrated in ensuring the long -term reliability of the augmented crystal tube under extensive load current conditions. Therefore, in these designs, monitoring and restricting equipment power consumption are the most important. The circuit shown in FIG. 69 is an example of a 5V, single power supply, and high -voltage side current monitor that can be included in the design of a voltage regulator with a folding restriction function or a large current power supply with a prying rod protection. The design uses the OP291 rail input voltage range to detect the voltage drop through the 0.1Ω current distribution. The P -channel MOSFET used as a feedback element converts the differential input voltage of the computing amplifier to current. The current is then applied to R2 to generate a voltage, which is a linear representation of the load current. The transmission equation of the current monitor is shown below:

For the displayed component value, the output transmission characteristics of the monitor are 2.5 v/a.

A 3V cold end compensation thermal puppet amplifier

OP291 low power operation makes it an ideal choice for 3V battery power applications, as shown in Figure 70 shown in Figure 70 Thermoelectric puppet amplifier. The K -type thermocouple is terminated in an equivalent block. In this block, a simple 1N914 diode continuously monitors the ambient temperature. By providing a small voltage calibrated by the 1.5 MΩ and 475Ω resistor to the calculation amplifier, the diodes come to the correction of thermal electricity generated in the end.

In order to calibrate the circuit, the thermocouple measurement connector was immersed in an ice bath of 0 ° C, and the 500Ω potential meter was adjusted to 0 V output. Next, immerse the thermocouple in a 250 ° C temperature tank or oven, and adjust the power level to the output voltage of 2.50 V. Within this temperature range, the K -type thermocouple is accurate to the range of ± 3 ° C, without linearity.

The single power source of the modem directly access the device

A part -time part of the modem is the telephone line interface. In the circuit shown in FIG. 71, the direct access device is used to send and receive data from the telephone line. The amplifier A1 is the receiving amplifier; the amplifier A2 and the amplifier A3 are the transmitter. The fourth amplifier A4 generates a fake ground between the power supply voltage and ground. AC coupling bipolar input signal requires this pseudo -place.

The transmission signal TXA is reversed by A2, and then input by A3 to provide differential drivers for the transformer. Each amplifier provides half of the driver signal. This is needed, because the single power supply is less fluctuation than the dual power supply. The amplifier A1 provides some gain for the receiving signal, and it also removes the transformer from the receiving signal from the receiving signaltransmit a signal. To this end, the driver signal from A2 is also feeded to the non -easy input terminal of A1 to offset the transformer transmission signal.

OP491's 3 MPAR bandwidth and rail output swing to ensure that it can provide the maximum possible driver to the transformer at the transmission frequency.

3 V, 50 Hz/60 Hz Affiliated wave filter, with fake ground

When processing the communication signal in a single power system, it is best to use a fake ground bias scheme. Figure 72 illustrates the circuit using this method. In this circuit, the fake ground circuit causes the source of the source to be biased, and the source trap filter is used to inhibit the 50 Hz/60 Hz power cord interference in the guardians of portable patients. The trap filter is very commonly used to suppress the frequency interference of the power line. These interference usually cover low -frequency physiological signals, such as heart rate, blood pressure, electro -electrocardiography, and electrocardiogram. This trap filter effectively inhibits 60 Hz picks of the filter Q of 0.75. Use a 3.16kΩ resistor to replace the 2.67kΩ resistor in the TWIN-T (R1 to R5), which can be configured with a source filter to inhibit the interference of 50 Hz.

The amplifier A3 is the core of a fake ground bias circuit. The voltage generated by its cushioning R9 and R10 is a reference for source trap. Because OP491 has the scope of the rail -to -orbit input, the 3V power supply is selected symmetrically at R9 and R10. The ring compensation scheme used around OP491 allows the operational amplifier to drive C6, a 1μF capacitor without oscillation. C6 maintains low impedance exchange ground within the operating frequency range of the filter.

The filter part uses a pair of OP491 with a dual T structure, which is very sensitive to the relative matching of the capacitance and resistance in the dual T section. Polycardia film is the first choice of capacitors. The relative matching of the capacitor and resistance determines the pseudonym of the filter. Use 1%resistance and 5%capacitor can produce satisfactory results.

Single power supply, semi -wave, and full -wave rectifier

The OPX91 device configured as a single power voltage follower can be used as a simple semi -wave rectifier in low frequency (u0026 lt; 2kHz) applications. The full -wave rectifier can configure a pair of OP291, as shown in Figure 73. The circuit works in the following ways. When the input signal is higher than 0V, the output of the amplifier A1 follows the input signal. Due to the output connected to A1 by the non -reversible input of the amplifier A2, the operation of the computing amplifier control forced the reverse input of A2 to have the same potential. As a result, the two terminals of R1 are equivalent, that is, there is no current flow. Because there is no current in R1, there is the same situation in R2; therefore, the output tracking input signal of the circuit. When the input signal is lower than 0 V, the output voltage of A1 is forced to 0 V. This situation is now forced to work as a reverse voltage follower, because A2's non -The change terminal is also 0 V.The output voltage at VOUTA is a full -wave rectifier version of the input signal.If necessary, you can get a buffer, semi -wave rectifier input signal version on Voutb.

The size of the shape