What is operational amplifier? basics concepts

• Automatic battery charger using op amp

Symbol:

The symbol of anOP-AMPis as shown

Usually, there are five pins in one OP-AMP
Invertingpin
Non-Invertingpin
Outputpin
PositiveSupply/Bias voltage pin
NegativeSupply Voltage/Ground pin

Dual power supply:

Most of the OP-AMP need to a DC power supply. The +Vs and -Vs are power supply terminal.

the +ve terminal of OP-AMP is connected to positive terminal of source and -ve terminal is connected to negative terminal of source.

Operation:

Ideally, theOP-AMPamplifies the input differential voltage (potential difference between inverting and non-inverting pin).

Vout = A_OL(V₊– V_–) where A_OLis the open-loop gain of the operational amplifier, V₊is the non-inverting input voltage and V_–is the inverting input voltage.
The gain of an OP-AMP is controllable. External resistor controls the gain of OP-AMPs. If there isno feedback,the gain is calledopen-loopgain, if thefeedbackispresentthe gain is calledclosed-loopgain.

If there is even a smalldifferentialvoltage at the input, it will cause an output voltage equal to the almostsupplyvoltage. It is due to the large gain of the amplifier. In open-loop gain, an operational amplifier acts as acomparator(compares the inverting and non-inverting voltage). If non-inverting voltage is greater than the inverting voltage, the output will be almost equal to the supply voltage because

(V₊– V_–) > 0 So, the output will be positive and equal to supply voltage while if inverting voltage is greater than thenon-invertingvoltage, the output will be almost equal to the negative supply voltage or ground.

If feedback is present then the gain is calledclosed-loopgain. Now, there are two configurations for the operational amplifier
1-invertingOP-AMP
2-non-invertingOP-AMP

Inverting operational amplifier

Inverting amplifier is the one which amplifies the signal and also inverts the signal. Its gain formula is

A_V= -(Rf/Rin) The negative sign shows that the signal gets inverted.

Non-Inverting Operational Amplifier:

A non-Inverting amplifier is the one that amplifies the signal without inverting it. Its gain formula is

A_V= 1 + (R2/R1)

Ideal Operational Amplifier

The ideal OP-AMP is the one that has the following characteristics.

• Infinite open-loop gain
• Infinite input resistance
• Zero output resistance
• Zero input offset voltage

No real OP-AMP is ideal because the real OP-AMP does not satisfy the above conditions.

Applications of Operational Amplifier:

In various electronic circuits OP-AMPs are present.

• Differential Amplifier
• Differentiators and Integrators
• Filters
• Oscillators and waveform generators
• 精密整流器
• Voltage clamping
• Analog to digital converters
• Digital to analog converters

OP-AMP tutorial:

• Opamp as Differentiator (active differentiator)

• OP-AMP integrator

• Voltage Follower OPAMP or buffer Amplifier

• Non-Inverting Amplifier(OPAMPs)

• Inverting amplifier (OPAMPs)

• 741 Op Amp, First Operational Amplifier IC

• What is operational amplifier? basics concepts

• Automatic Battery Charger Circuit using LM358 OP-AMP