Blog  /  lm 2904 -A Guideline on Low-power Dual Op-amps

lm 2904 -A Guideline on Low-power Dual Op-amps

Operational amplifiers are high gain electronic voltage amplifiers with single-ended outputs and differential inputs. 
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Type of op-amp

Source; Wikipedia

 

Today, we will discuss the LM2904 dual op-amp suitable for double, single, and quad devices. The product category is an offset voltage operational amplifier with enhanced features, as we'll see.

 

What is an lm 2904?

 

LM2904 is an amplifier IC comprising two internally frequency Op-amps that are high gain and independent. Moreover, its design enables its operation over several voltages from single power supply systems. As such, it is common in digital systems in any electronic device.

DIP-8 op-amp

(DIP-8 op-amp)

Despite having slew rate limitations, LM2904 ICs still have improved performance. Its circuit combination of an inverting and non-inverting amplifier contributes to an adjustable reference voltage circuit. The adjustment causes a change from a negative of any input voltage to the input voltage itself.

 

lm 2904 Pin Configuration

 

LM2904 is an 8-pin IC, and we have described its pinout in the table below;

 

LM2904 pinout (similar to lm358)

LM2904 pinout (similar to lm358)

Source; Wikipedia

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lm 2904 Features

 

LM2904 op-amp features and specifications include the following;

It has a standard supply voltage ranging from 3V to 26V and an operating supply current of 250uA. Additionally, its output voltage range often comprises the negative power supply voltage.

Then, its common-mode rejection ratio (CMRR) is 70dB, whereas its power supply rejection ratio (PSRR) is 50dB.

Thirdly, it has a significant DC voltage gain of 100dB.

Its input bias current (Ib) is 250nA, while its output current per channel is 30mA.

Fifthly, it has an input offset voltage (Vos) of 7 mV.

It has an operating temperature range of 40°C to +125°C.

It also has a unity gain or wide bandwidth of 1MHz and a quiescent current of 300µA per amplifier.

Lastly, LM2904 IC is available as an 8-bump DSBGA chip-sized package technology. You can additionally have it in standard packages like VSSOP, SOIC, and TSSOP.

 

How to Use LM2904 IC 

 

Fortunately, LM2904 IC requires few components in application circuits. Let us consider the high input impedance non-inverting application circuit that uses LM2904 IC.

 

Circuit diagram involving LM2904 IC 

Circuit diagram involving LM2904 IC 

 

Circuit Explanation

First, the inverting pin connects to the ground via a 10k resistor, whereas the non-inverting pin gives the input supply.

Then, the circuit provides a closed-loop 3dB bandwidth similar to a closed-loop gain dividing the amplifier unity-gain frequency. In addition, it gives a closed-loop boost that's equal to the ratio of R1 to the sum of R2 and R1.

Therefore, you can use the formulae with values of R2 and R1 to calculate the circuit's gain: G = 1+ R2/R1.

R1 = 10kΩ

R2 = 99× value of R1 (990kΩ)

You can also replace the 990kΩ with 1MΩ to get a desirable gain tolerance, our case being 101.

lm 2904 Application

There is a wide range of LM2904 applications in the market like in;

Comparators (loop regulation and control),

Dynamic latched comparator symbol

Dynamic latched comparator symbol

Source; Wikimedia

 

Transducer amplifiers,

Voltage frequency drives,

DC gain blocks, oscilloscopes, digital multimeters,

 

digital oscilloscope

(digital oscilloscope)

 

Conventional op-amp circuit design concepts, and

Voltage follower applications, adder, summer, differentiator, integrator, etc.

Conclusion

 

To conclude, lm2904 IC is a dual package op-amp that circuit design engineers have made. It operates on a standard 3.3-V power supply voltage and high differential input voltage capability. Moreover, you can always speed up the op-amp prototyping and testing by using a suitable DIP adapter.

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