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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Calvert Created 10 August Last revised 19 September Multi-channel audio mixer circuit using LM john July 27, 4 Comments.

Feedback from the output to the inverting input acts to reduce the difference current, which in normal operation is very small. The input and feedback resistors are as with the familiar circuit, and the gain in this lk3900 should be The LM is specially useful when only a single power supply is available.

The relaxation oscillator makes use of a Schmitt trigger, with positive feedback. There is no common-mode voltage range at all!

A simple multi-channel audio mixer circuit using LM quad amplifier is given below. The l3900 consists of 4 channel quad amplifier LM 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.

Quad Amplifier | LM

Connect Ch 1 to the input voltage, and Ch 2 to the output. The input resistor turns the applied voltage into a current, while the feedback resistor causes the output to rise to a value supplying an equal current to the inverting input.

It has been replaced by a common-mode current range by the current differencing. It looks like the same circuit for the usual op-amp, but here the resistors are necessary. The LM can use from 4 to 36 V total supply voltage. The capacitor charges until its voltage reaches this level, but then the ouput goes low and it begins to discharge again.


The unity-gain buffer is a special case of the noninverting amplifier, shown at the right with biasing by means of a voltage divider. An inverting Schmitt trigger is shown at the right. The input and supply voltages can be exchanged to give a noninverting circuit.

In this case, the bias does not depend on the supply voltage.

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

The slew rate of km3900 LM was evident in the output waveform. In this case, the bias is about 10 x 0. This is a very graphic illustration of Schmitt trigger operation.

These are the trip levels expressed in currents. A voltage regulator with a Zener in the feedback loop is shown at the right.

The label “Norton” refers to the Norton equivalent circuit for a current source. Multi channel audio mixer circuit.

National Semiconductor

This is an AC amplifier, with coupling capacitors at input and output so there is no worry about DC bias levels, which can be l3900 as necessary. For a 12V supply, these levels are about 7. The Norton op-amp can also be used to make active filters and oscillators; see the National Semiconductors application note AN for details. Capacitors C1 to C4 are the decoupling capacitors for the corresponding channels.

Note the symbol for the Norton op-amp, that has a current source between the inputs, and an arrow on the noninverting input. Two mic audio inputs and two direct line inputs are available in this circuit. C5 is the output decoupling capacitor. The output goes from high to low when the input reaches 7 V, and from low to high when it goes lm390 6 V, with a hysteresis of 1 V.

Your email address will not be published. This is a very rough calculation, so we expect only general agreement. The divider supplies a current into what is effectively a unity-gain buffer to reproduce its voltage at the output. There is one set of power connections for the four amplifiers, but they are otherwise independent. LM pin configuration and architecture. You may also like: The output, however, is a voltage as with the usual op-amp.


When the capacitor voltage reaches this level, the ouput again goes high, and the cycle repeats. Lm300, can I use 3. This is just like the usual op-amp, except with current instead of voltage. The circuit is not as precise as the usual one, with small shifts due to the diode drops at the input, but the circuit is useful and furnishes a reasonable input resistance of 1M.

With the values shown, this circuit oscillated at Hz, the output swinging from near zero to Buffered, this would be an easy way to get a sine wave. A Hz triangle wave from a function generator makes a suitable input. The difference is the 39k resistor at the noninverting input. Another biasing scheme for the inverting amplifier is shown at the left.

They also provide a large output swing. By adding the same circuit parallel with this, you can increase the number of inputs according to the applications. Instead of a differential amplifier, the input stage is the current-differencing circuit shown at the right. When you test this circuit, the scope lm9300 for input and output can be superimposed with proper setting of the gain, and the inversion is obvious.

Previous post Next post. This voltage is added to the Zener voltage at the output.