Features

1. Low input bias current: Typical 50 Pa

Low input noise current: 0.01 PA/√Hz Typical Value

Low total harmonic distortion

Low power supply current: 8 mAh (typical value)

gain bandwidth: typical 3 mHz

High turnover rate: typical 13 v/ms

[

123] 2. Application

Electric Integrated System: UPS

Drive and control solution: AC inventor and VF drive

Renewable energy: Solar inverter

Professional audio mixed

oscilloscope

3 · Explanation

LF347 and LF347B devices are low cost, high -speed, JFET Enter the operational amplifier. They require low power current while maintaining large -gain bandwidth products and rapid conversion rates. In addition, their matching high -voltage JFET input provides low input bias and bias current. LF347 and LF347B can be used for applications such as high -speed integrals, from digital to simulation converters, sampling and maintaining circuits, and many other circuits. The LF347 and LF347B devices are characterized by running at 0 ° C to 70 ° C.

Absolutely maximum rated value

exceeding the free air temperature range of work (unless otherwise instructions) (1)

(1) more than more The stress of the absolute maximum rated value may cause permanent damage to the device. These are the limited stress level, which does not mean that the function operation of the device under these or any other conditions is beyond the recommended conditions of the suggestion. Long -term exposure to absolute maximum rated conditions may affect the reliability of the device.

(2) Unless there are other regulations, the absolute maximum negative input voltage is equal to the negative power voltage.

(1) JEDEC file JEP155 stipulates that 500-V HBM allows the use of standard ESD control processes for safe manufacturing.

(2) JEDEC file JEP157 stipulates that the 250 volt clean development mechanism allows safety production and standard static discharge control process.

Electrical features: lf347

More than the free air temperature range (unless otherwise explained)

(1) The full range is 0 to 0 ° C to 70 ° C.

(2) The input bias current of the input operation amplifier in the field effect tube is normal ending reverse current and is sensitive to temperature. The pulse must use technology that can make the knot temperature as close to the ambient temperature as much as possible.

(3) Measuring the voltage amplitude value of the two power supply at the same time increases or reduces the battery voltage suppression ratio.

Overview

LF347 is a JFET input computing amplifier with low input bias and bias current and rapid conversion rate. Each amplifier has a JFET input (for high input impedance) and integrated in a single -chip chip. Due to the output impedance of the resistance 200Ω, the output is short -circuited

Feature description

The turnover rate

The conversion rate is the input of the operation amplifier. The conversion rate of these devices is 13 volts/microsecond.

Equipment function mode

When the power supply is connected, these devices are connected to the power supply. This device can be used as a separate power supply to operate the operation amplifier or dual -power amplifier depends on the application.

Application information

LF347 has four independent amplifiers. They have very low input bias currents and allow the resistance to the use of higher feedback networks. The scope of the co -input model is usually the power rail. The lower model range does not include negative power rails; it must be at least 4 V and larger. The output resistance is 200Ω to prevent the device from short circuit.

Typical application

The typical application of the operation amplifier is the inverter amplifier. This amplifier has a positive voltage input and make it a negative voltage of the same size. Similarly, it will make the voltage positive.

Design requirements

The choice of power supply voltage must make it greater than the input voltage range and output range. For example, this application zoom the signal from ± 0.5 V to ± 1.8 V. Set the power supply to ± 12 V to adapt to this application.

Detailed design program

Determine the gain required for the reverse amplifier:

When the required gain is determined, choose a value for RI or RF. It is best to choose the value within the KΩ range because the amplifier circuit uses the current within the milliamp. This can ensure that the parts do not draw too much. For this example, 10 kΩ is for RI, which means that 36 kΩ is used for R, such as equal 3.

Layout Guide

In order to obtain the best operating performance of the device, please use a good PCB layout practice, including including : The noise can be transmitted to the analog circuit through the power pin of the entire circuit, and the operational amplifier. The barrier capacitance is used to reduce the local power supply of the coupling noise simulation circuit by providing low impedance. -Connect low ESR, 0.1-μF ceramic side electric container between each power supply foot and grounding, and place it as close to the device as possibleEssence A single bypass container is suitable for providing applications from V+grounding.

Circuit simulation and the individual grounding of the digital part are one of the simplest and most effective noise inhibition methods. A layer or multi -layer on a multi -layer polychide is usually used for the ground plane. The horizon helps heat dissipation and reduce electromagnetic interference noise. Ensure that they are separated by numbers and simulation ground, and pay attention to the flow of ground current. For more detailed information, see chapter excerpts, circuit board layout technology (Sloa089). In order to reduce parasitic coupling, keep the input channel away from the power supply or output channel as much as possible. If they cannot be separated, it is best to pass the sensitive marks vertically and parallel to the noise trajectory. Make external components as close to the device as much as possible. Keep RF and RG close to reverse

Layout Guide (continued)

Enter minimal parasitic capacitors, as shown in the layout example. Turn the length of the input trajectory as much as possible. Always remember that the input tracking is the sensitive part of the circuit. Consider installing a driver's low impedance protection ring around the critical track. The protective ring can significantly reduce the leakage current from different potentials.