Features

Rail output swing

Single power operation: +3 V to +36 V

Low offset voltage: 300 mv

Gain bandwidth accumulation: 75 kHz

High -opening gain gain: 1000 V/MV

The unit gain stable

Low power current/each amplifier: maximum 150 mA

] Application

battery power supply instrument

Servo amplifier

Executive drive

Sensor regulator

Power control

] Generally explaining

The combination of rail output swing and DC accuracy is the key feature of OP495 Four and OP295 dual CBCMOS operational amplifiers. By adopting a double -pole front end, lower noise and higher accuracy than CMOS design. The input and output range include negative power, providing users with the ""zero input/zero output"" function. For users who use 3.3 volt systems (such as lithium batteries), OP295/OP495 specifies for 3 volt operations.

For the opening of the ring, the minimum gain is 1000V+A, and the maximum gain is 1000V/A. The performance of this can be used to achieve high -precision systems, and even in the design of single power supply.

OP295/OP495 has the ability to change rails and loads +15 mAh, which is an ideal driver for power transistors and the ""H"" bridge. This allows the design to achieve higher efficiency and transmit more power to the load than before without using separate components. For applications, it requires driving sensor loads, such as transformers, which is also possible to improve efficiency. Compared with the CMOS rail -to -rail bars, the stability of the driving capacitance load is another advantage of the design. This is very useful for driving coaxial cables or large FET transistors. OP295/OP495 is stable when the load exceeds 300 PF.

OP295 and OP495 are specified within the extended industry (–40 ° C to+125 ° C). OP295 has 8-pin plastic and ceramic DIP plus SO-8 surface installation and packaging. OP495S has 14-pin plastic and SO-16 surface installation packaging. For the MIL-STD-883 data table, please contact the local sales office.

pin connection

Dice feature

OP295 mold size 0.066 × 0.080 inches, 5280 Flash inch. The dense ear base (back of the chip) is connected to V+. Crystal count, 74.

OP495 mold size 0.113 × 0.083 inches, 9380 square inch. The dense ear base (back of the chip) is connected to V+. Crystal count, 196.

OP295/OP495 - Typical features

Application Railway to railway application Information

OP295/OP495 has a very wide co -mode input range, extending from the ground to a positive power range of about 800 millival. In the buffer application of the input voltage that may exceed the input range of the co -mode, there is a trend of using OP295/OP495. Because the high input range and rail -to -orbit output range may initially look feasible. But above the scope of the co -mode input, of course, the amplifier is highly non -linear. Therefore, when the orbit output is required, there are always some minimum gains. According to the scope of the input co -mode, the gain should be at least 1.2.

Lower falls benchmark

OP295/OP495 can be used to obtain a low voltage reference voltage of 2.5 V or other 4.5 V for other 4.5 V, for high resolution A/D working at high resolution at +5 V power. converter. The circuit in FIG. 1 will provide a current of up to 10 mA. Its vacant drop voltage is only 20mV. The circuit will supply a power supply of +5 volt power above 3.5 mAh.

Low noise, single power supply front amplifier

The design of most single power supply amplifiers is to reduce the power current and sacrifice higher Voltage noise. This weighing may be necessary because the system must be powered by the battery. However, because the resistance of all circuits tends to higher, in addition to the voltage noise of the operation amplifier, Johnson noise (resistor thermal noise) is also an important contributor to total noise of the system.

The selection of single -chip operational amplifiers combined with low noise and single power operation characteristics is quite limited. The noise of most single power supply amplifiers is about 30 nv/√Hz to 60 nv/√Hz, and the single power amplifier with noise below 5 nv/√Hz does not exist.

In order to achieve low noise and low power voltage operation, discrete design may provide the best solution. The circuit in FIG. 2 uses OP295/OP495 rail to rail bars and matching PNP transistor to MAT03, and the zero input/zero output single power supply with 0 input voltage noise is NV/√Hz. The R5 and R6 set the gain to 1000, making the circuit the ideal circuit to maximize the dynamic range when enlarging the low level signal in a single power supply. OP295/OP495 provides rail pairing output swing, allowing the circuit to pass from 0 to 5 voltsRun. Only half of OP295/OP495 is used, and another unprepared operation amplifier is used elsewhere.

The input noise is controlled by the MAT03 transistor and the level of the collector current. Increasing the range of the range will reduce the voltage noise. The circuit was tested at a current of 1.85 mAh and 0.5 mAh. In these two cases, the input voltage noise is 3.1NV/√Hz and 10nv/√Hz, respectively, which are indeed a balance between the high -collection electrode current that will cause the power current, bias current, and current noise. All these parameters will increase with the increase of the current electrode current. For example, usually, hfee u003d 165 of MAT03. This will generate 11 μA and 3μA bias currents. Based on high bias currents, this circuit is most suitable for low -source impedance applications, such as magnetic pickups or low impedance degeneration regulations. In addition, high source impedance reduces noise performance. For example, 1 k the resistor generates a broadband noise of 4 nv/√Hz, which is greater than the front amplifier.

The setting electrode current is set by R1 combined with LED and Q2. LED is a 1.6V ""Zina"". Its temperature coefficient is close to the base emitter of Q2, which provides a constant 1.0V voltage drop on R1. When R1 is equal to 270 , the tail current is 3.7 mA, and the collector current is half of 1.85 mA. You can change the value of R1 to adjust the set electrode current. Whenever R1 changes, R3 and R4 should also be adjusted. In order to maintain the scope of co -mode input, which includes grounding, the collector of Q1 and Q2 should not exceed 0.5V, otherwise saturation will be saturated. Therefore, R3 and R4 must be small enough to prevent this from happening. The overall performance of their values u200bu200band the two different values u200bu200bof R1 are summarized in Table 1. Finally, the potential meter R8 is required to adjust the offset voltage to zero it. OP90 can be used as an output amplifier to obtain similar performance, saving about 185 μA power current. However, the output swing does not include the right track, and the bandwidth will be reduced to about 250 Hz.

Driving for heavy load

OP295/OP495 is very suitable to increase the load current by using power crystal tube, Darlingon or FET. The ability to swing to any orbit can ensure that the device is started. This has led to more power load and efficiency improvement of standard computing amplifiers and their limited output swing. OP295/OP495 can also drive the power FET because it can drive hundreds of Picofarads capacitor loads without oscillation.

Without adding an external crystal tube, OP295/OP495 can drive a load of more than ± 15 mAh by ± 15 or +30 power supply. This driving capacity will be reduced at a lower power supply voltage. At ± 5At the time of 流, the driving current is ± 11 mAh.

In a single power supply application, two directions of the driving motor or actuator are usually completed using the ""H"" bridge. This principle is shown in Figure 3A. Through a +5 volt power, the driver can drive 0.8 volt of 4.2 volts in two directions. Figure 3B shows the voltage of the driver's inverter and non -inverted output. There is a small cross failure that is frequently dependent, which will not cause problems unless this is a low -distorted application such as audio. If this is used to drive the inductive load, you must add a diode clip to protect the bridge from the induction response.

Direct access arrangement

OP295/OP495 can be used for single power direct access device (DAA), as shown in Figure 4. This picture shows a typical DM part, which can be powered by a single+5 volt power supply, or it can also work on +3 volt power, just modify it slightly. The amplifier A2 and A3 are configured so that the transmitting signal TXA is reversed by A2 instead of A3. This device drives the transformer in a differential mode, so that the driving force of the transformer is doubled on a single amplifier device. This application uses the ability of OP295/OP495 to drive the capacitance load and saves electricity in single -power applications.

Single power supply meter amplifier

OP295/OP495 can be configured as a single power instrument amplifier, as shown in Figure 5. In our example, VREF is set to

, and VO is measured relative to VREF. The input -co -mode voltage range includes the grounding and output swing of the two orbit.

The gain of the instrument amplifier of the resistor RG. The minimum gain is 6 (no RG). All resistors should match the absolute value and temperature coefficient to maximize the improvement of co -mode inhibitory performance and reduce drift. This instrument amplifier can work at a power supply voltage as low as 3 volts.

Single power RTD thermometer large device

This resistor temperature detector amplifier uses OP295/OP495 rail swing to achieve high bridge voltage with a low 5 volts of power. OP295/OP495 amplifier provides a constant 200 μA current for the bridge. The reflow current of the parallel resistor 6.19 k and 2.55 m decreases, and generates a servo to 1.235V voltage. The voltage is determined by the AD589 band gap. The 3 wire resistor temperature detector provides equal wire resistance reduction in the two 100 the legs are provided to improve the accuracy.

AMP04 amplified differential bridge signals and converted it to a single -end output. The gain from 332 resistor and 50 potential meterLink resistance settings. The gain zoom output to generate 4.5 V full markers. 0.22 μF capacitors of the output terminal provides 7 Hz low -pass filters to maintain noise at the lowest level.

A cold -end compensation, battery power supply puppet amplifier

OP295/OP495 per amplifier consumes a static current of 150 μA, making it suitable for battery power supply Temperature measurement instrument. The K -type thermocouple is terminated in an equivalent block. By adding the same but opposite thermal power to the amplifier, the ambient temperature of the environmental temperature of the correction end can be continuously monitored and corrected, thereby eliminating the error of the cold end introduction.

When calibration, the thermocouple measurement connector was immersed in 0 ° C ice bath, and the zero -adjusting potential meter was adjusted to zero output. Then immerse the thermocouple in a temperature groove or oven of 250 ° C, and adjust the tank to the output voltage of 2.50 V, which is equivalent to 250 ° C. Within the temperature range, the K -type thermocouple is very accurate and generates quite linear transmission characteristics. Without linearity, it can reach the accuracy of ± 3 ° C.

Even if the battery voltage is allowed to drop below 7 volt, the rail switching temperature allows the temperature to measure to 700 ° C. However, if the temperature is higher than 250 ° C and the thermocouple becomes quite non -linear, it may need linearity. The power supply current from the 9V battery is slightly lower than 500 μA.

Only 5V, 12 -bit DAC, swing 0 V to 4.095 V

Figure 8 shows a complete voltage output DAC. With a +5 V power supply, there is a wide output voltage switching A splitted. The serial input 12 -bit D/A converter is configured to the voltage output device, and the 1.235V reference voltage is powered by the current output pins (IOUT) DAC. Usually the input VREF now becomes output.

The output voltage from DAC is the binary weighted voltage with the benchmark. The voltage is obtained by the output amplifier, so that DAC has a transmission function of 1MV per special 1MV.

4–20 MA current circuit transmitter

FIG. 9 shows a self -powered 4–20 MA current circuit transmitter. The entire circuit floats upward from a single power supply (12 volts to 36 volts). Signals within a range of 4 to 20 mAh in the power current. Therefore, 4mo has determined the current budget that the baseline circuit must run. This circuit consumes only 1.4 mA's maximum static current, so that 2.6 mAh current can be used for additional signal regulating circuits or power supply to the bridge circuit.

A 3 volts of low voltage differential linear stabilizer

Figure 10 shows a simple 3V voltage regulator design. The regulator can provide 50 mAh loadThe current, at the same time allows a voltage voltage of 0.2 volt. OP295/OP495 rail -to -orbit output swing is convenient to drive the MJE350 transistor, without special driving circuits. In the case of air load, its output swing is smaller than that of the base of the pipe transistor transmitting pole voltage, and the device is almost turned off. Under the full load and low-emission pole-set voltage, the transmission resistance β tends to decrease. The additional base current can be easily processed by OP295/OP495.

The amplifier puts the output servo to a constant voltage. This voltage will feed a part of the signal to the error amplifier.

The higher output current reaches 100 mAh, which can achieve a higher voltage of 3.8 volts.

FIG. 11 shows the recovery characteristics of the regulator, when its output experience changes from a step current from 20 mia to 50 mAh.

Low -voltage difference, 500 mAh voltage regulator, can be folded and restricted

Add the second amplifier in the adjustment loop, as shown in Figure 12, you can provide output current surveillance monitoring Device and foldable current protection.

The amplifier A1 provides a large error release for the normal voltage adjustment circuit. As long as the output current is less than 1 amp, the output of the amplifier A2 will swing to the ground, so that the diode is pressed in reverse, thereby effectively leaving itself from the circuit. However, when the output current exceeds 1 amp, the voltage generated by the sensor of the sensor A2 through 0.1 the voltage generated by the sensing resistor will force the output of the amplifier A2, so that the diode is biased forward, and the current restricted loop is turned off. At this time, the lower output resistance of A2 controls the driver of the power MOSFET transistor, which effectively removes the A1 voltage adjustment loop from the circuit.

If the output current continues to be greater than 1 amp, the current limit load will force the load current to reduce, which will cause the corresponding output voltage to decrease. When the output voltage decreases, the current limit threshold also decreases slightly, resulting in the output current decreased as the output voltage decreases. When 1V output, the output current is less than 0.2A. This ""folding"" effect greatly reduces the power consumption in short circuit conditions, so that the power supply is more tolerant in terms of thermal design requirements. The small hot sinking on the power MOSFET can tolerate it.

OP295's rail -to -rail swing requires the power MOSFET to have a higher gate driver to provide a more comprehensive enhancement for the transistor. The regulator shows a voltage drop of 0.2 volt under a load current of 500 mA. When output of 1 ampel, the voltage voltage is usually 5.6 volts.

Fangbo oscillator

The circuit in FIG. 13 is a square wave oscillator (pay attention to positive feedback). OP295/OP495 rail -to -rail swing helps maintain a constant oscillation frequency, even if the power supply voltage changes greatly. Consider a system of battery power supply, the voltage in whichNot adjusted and descending time. That Rail-TO-RAIL SWING ensures that non-conversion inputs see complete V+/2 instead of a small part of it.

The constant frequency comes from such a fact, that is, 58.7 k the feedback sets the Schmidt trigger threshold level, which is proportional to the power supply voltage, as well as the RC charging voltage level. Therefore, the RC charging time and frequency remain unchanged and have nothing to do with the power supply voltage. The conversion rate of the amplifier limits the maximum value of the oscillation frequency to about 800Hz under the+5V power supply.

Single power differential speaker driver

As a differential speaker driver connection, OP295/OP495 can provide a current of at least 10 mAh to the load. Under 600 load, OP295/OP495 can swing near 5 volts in the peak in the load range.

High -precision, single power supply, low power consumption comparison device

OP295/OP495 constitutes a precise opening comparator. For single+5 V power, the offset error is less than 300 μV. Figure 15 shows the response time of OP295/OP495 when driving at 4 MV. The response time of the rising edge is 4 milliseconds, and the response time to the decline edge is 1.5 milliseconds.

The size of the shape

The size unit is inch and (mm)