LM3900 PDF

LM LM LM Quad Amplifiers. General Description. The LM series consists of four independent dual input internally compensated amplifiers . Texas Instruments LM Series Operational Amplifiers – Op Amps are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for . lm are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for lm

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Leave a Reply Cancel reply Your email address will not be published. The extremely high input resistance of the voltage or FET-input op-amp is not obtained, however. The usual op-amp responds to a differential voltage at its inputs, but the LM responds to a differential current.

The circuit consists of 4 channel quad amplifier LM Its output swings llm3900 very near ground to a diode drop below the positive supply.

The output, however, is a voltage as with the usual op-amp. The difference is the 39k resistor at the noninverting input. These amplifiers provide a wide range of voltage inputs and very good response for all audio frequencies. To pm3900 this circuit, assume for simplicity that the output swings from 0 to the supply voltage V.

The built in amplifier of each section amplifies every audio input separately and is fed to the output terminals.

National Semiconductor – datasheet pdf

These are the trip levels expressed in currents. Again, the high input impedance of the voltage op-amp is not obtained. The capacitor charges until its voltage reaches this level, but then the ouput goes low and it begins to discharge again. The LM is very convenient for AC amplifiers. You may also like: The LM is specially useful when only a single power supply is available.


This is an AC amplifier, with coupling capacitors at input and output so there is no worry about DC bias levels, which can be chosen as necessary.

A Hz triangle wave from a function generator makes a suitable input. It looks like the same circuit for the usual op-amp, but here the resistors are necessary.

Muti-channel audio mixer circuit based on LM IC. Four channels.

lm900 The label “Norton” refers to the Norton equivalent circuit for a current source. Another biasing scheme for lm33900 inverting amplifier is shown at the left. For a 12V supply, these levels are about 7. A pass transistor can be added at the output for additional current capacity the LM can be depended on only for about 20 mA when sinking current.

Multi channel audio mixer circuit. When the capacitor voltage reaches this level, the ouput again goes high, and the cycle repeats.

By adding the same circuit parallel with this, you can increase the number of inputs according to the applications. The relaxation oscillator makes use of a Schmitt trigger, with positive feedback.

National Semiconductor

The LM is a pin DIP containing four identical op-amps, each with inverting and noninverting inputs and an output. The first circuit to look at is the inverting amplifier, shown at the right.

The measured values from the scope were 3. They also provide a large output swing. I think resistors R8 and R10 should be taken out. Buffered, this would be an easy way to get a sine wave. This voltage is added to the Zener voltage at the output.

The output goes from high to low when the input reaches 7 V, and from low to high when it goes below 6 V, with a hysteresis of 1 V.


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Here, the current supplied by the output is returned to the inverting input, where it flows out the k bias resistor, so the bias is positive.

It supplies a current 12 – 0. Hello, can I use 3. The LM can use from 4 to 36 V total supply voltage. Multi-channel audio mixer circuit using LM john July 27, 4 Comments.

Equal currents supplied to the two inputs are not amplified. Connect Ch 1 to the input voltage, and Ch 2 to the output. It relies on the diode drop at the inverting input to supply a current proportional to V bewhich is then amplified by the feedback resistor. In this case, the bias is about 10 x 0.

The unity-gain buffer is a special case of the noninverting amplifier, shown at the right with biasing by means of a voltage divider. Previous post Next post. Each input is connected to the inverting terminal of LM C5 is the output decoupling capacitor. Note the symbol for the Norton op-amp, that has a current source between the inputs, and an arrow on the noninverting input.

The Norton op-amp can also be used to make active filters and oscillators; see the National Semiconductors application note AN for details. This is a very graphic illustration of Schmitt trigger operation. Feedback from the output to the inverting input acts to reduce the difference current, which in normal operation is very small.