TL072 Pinout: Introduction, Uses, and Applications of The Audio IC

Introduction to the TL072

The TL072 is a member of the TL07x family of op-amps, manufactured by Texas Instruments. It features two independent, high-performance op-amps in a single 8-pin package. The TL072 is known for its low noise, wide bandwidth, and high slew rate, making it suitable for a wide range of analog signal processing applications, particularly in the audio domain.

Key Features of the TL072

Dual op-amp in a single package
Low noise: 18 nV/√Hz at 1 kHz
Wide bandwidth: 3 MHz
High slew rate: 13 V/μs
Low input bias current: 65 pA
Wide supply voltage range: ±5 V to ±15 V
High Input Impedance: 1012 Ω
Short-Circuit Protection

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TL072 Pinout

To effectively use the TL072 in your projects, it is crucial to understand its pinout. The TL072 comes in an 8-pin dual in-line package (DIP) or an 8-pin small outline integrated circuit (SOIC) package. The pinout for both packages is identical.

Pin Number	Pin Name	Description
1	OUT A	Output of op-amp A
2	IN- A	Inverting input of op-amp A
3	IN+ A	Non-inverting input of op-amp A
4	V-	Negative supply voltage
5	IN+ B	Non-inverting input of op-amp B
6	IN- B	Inverting input of op-amp B
7	OUT B	Output of op-amp B
8	V+	Positive supply voltage

Connecting the TL072

When using the TL072, it is essential to provide proper power supply connections and decoupling capacitors to ensure stable operation and minimize noise.

Connect the V+ pin (pin 8) to the positive supply voltage, typically between +5 V and +15 V.
Connect the V- pin (pin 4) to the negative supply voltage, typically between -5 V and -15 V.
Place a 0.1 μF ceramic capacitor between the V+ and V- pins, as close to the IC as possible, to decouple the power supply and reduce high-frequency noise.
If using a single supply, connect the V- pin to ground and bias the non-inverting inputs of both op-amps to half the supply voltage using a Voltage Divider.

Uses and Applications of the TL072

The TL072’s excellent performance characteristics make it suitable for a wide range of audio applications. Some common uses include:

1. Preamplifiers

The TL072 is often used as a preamplifier stage in audio systems, providing high input impedance and low noise amplification for microphones, guitars, and other audio sources. Its wide bandwidth and high slew rate ensure accurate reproduction of fast transients and high-frequency content.

2. Active Filters

The TL072 is well-suited for implementing active filters, such as low-pass, high-pass, and band-pass filters. Its low noise and wide bandwidth allow for the design of filters with precise cutoff frequencies and minimal distortion.

3. Equalizers

In audio equalizers, the TL072 can be used to create adjustable frequency-selective amplifiers, allowing users to boost or cut specific frequency bands. Its low noise and high slew rate ensure accurate equalization without introducing unwanted artifacts.

4. Oscillators

The TL072 can be configured as a stable oscillator, generating sine, square, or triangle waves for various audio applications, such as test signal generation or modulation.

5. Mixers

In audio mixing applications, the TL072 can be used to combine multiple audio signals while providing low noise and minimal distortion. Its wide bandwidth ensures accurate summing of signals across the entire audio frequency range.

6. Voltage-Controlled Amplifiers (VCAs)

The TL072 can be used as a building block for voltage-controlled amplifiers, where the gain of the amplifier is controlled by an external control voltage. VCAs are commonly used in audio dynamics processors, such as compressors and expanders.

Application Example: Simple TL072 Preamplifier

To demonstrate the use of the TL072 in a practical application, let’s design a simple preamplifier circuit.

Circuit Diagram

             +15V
              |
              |
             +-+
             | |
             | | R2
             | | 10k
             | |
             +-+
              |
              +-----+------+
              |     |      |
  IN -->--+---+     |      +----+---> OUT
          |   |     |      |    |
         +-+  |  +--+--+   |   +-+
         | |  |  |     |   |   | |
         | |  |  |     |   |   | | R4
  C1     | |  |  | TL072   |   | | 10k
  1uF    | |  |  |         |   | |
         | | R1  |         |   | |
         | | 1M  |         |   +-+
         | |  |  |         |    |
         +-+  |  +--+--+   |    |
          |   |     |      |    |
          +---+     |      +----+
              |     |      |
             +-+    |      |
             | |    |      |
             | | C2 |      |
             | | 1uF|      |
             | |    |      |
             +-+    |      |
              |     |      |
              +-----+------+
                    |
                   GND

Component Values

R1 = 1 MΩ (input impedance)
R2 = 10 kΩ (feedback resistor)
R4 = 10 kΩ (output impedance)
C1 = 1 μF (input coupling capacitor)
C2 = 1 μF (feedback capacitor)

Circuit Explanation

This simple preamplifier circuit uses one of the TL072’s op-amps as a non-inverting amplifier. The input signal is coupled to the non-inverting input (pin 3) through the input coupling capacitor C1, which blocks any DC offset. The input impedance is set by resistor R1, ensuring minimal loading of the input source.

The gain of the preamplifier is determined by the ratio of the feedback resistor R2 to the input impedance R1. In this example, the gain is approximately unity (1), as R2 and R1 are equal. The feedback capacitor C2 provides high-frequency roll-off, helping to reduce noise and prevent oscillation.

The output of the op-amp (pin 1) is connected to the output through resistor R4, which serves as a simple output buffer, providing a low output impedance for driving subsequent stages.

Frequently Asked Questions (FAQ)

Q: Can the TL072 be used with a single supply voltage?
A: Yes, the TL072 can be used with a single supply voltage. In this case, connect the V- pin (pin 4) to ground and bias the non-inverting inputs of both op-amps to half the supply voltage using a voltage divider.
Q: What is the maximum supply voltage for the TL072?
A: The maximum supply voltage for the TL072 is ±15 V. However, it is important to consult the manufacturer’s datasheet for the specific version of the TL072 you are using, as some variants may have different maximum supply voltages.
Q: Can the TL072 be used for video applications?
A: While the TL072 is primarily designed for audio applications, it can be used in some video applications that do not require extremely high bandwidths. However, for demanding video applications, it is recommended to use op-amps specifically designed for video, such as the LM6172 or the OPA360.
Q: How do I reduce noise in my TL072 circuit?
A: To reduce noise in your TL072 circuit, follow these guidelines:
Use proper power supply decoupling capacitors, placed as close to the IC as possible.
Keep signal paths short and away from power supply lines and other noise sources.
Use shielded cables for sensitive signal connections.
Properly ground the circuit, using a star grounding configuration if possible.
Consider using low-noise resistors in critical signal paths.
Q: Can I replace a TL072 with a similar op-amp, like the TL082 or NE5532?
A: In many cases, you can replace the TL072 with similar Dual Op-amps, such as the TL082 or NE5532. However, it is essential to compare the key specifications, such as noise, bandwidth, slew rate, and pinout, to ensure compatibility with your specific application. Always consult the manufacturer’s datasheets when making substitutions.

Conclusion

The TL072 is a versatile and widely-used dual op-amp IC that offers excellent performance characteristics for audio applications. By understanding its pinout, uses, and applications, you can effectively incorporate the TL072 into your projects, whether you are designing preamplifiers, active filters, equalizers, or other analog audio circuits.

When working with the TL072, remember to follow proper power supply decoupling techniques, keep signal paths short, and properly ground your circuit to minimize noise and ensure stable operation. With its low noise, wide bandwidth, and high slew rate, the TL072 is an excellent choice for a wide range of audio applications, from simple preamplifiers to complex signal processing chains.

As you explore the world of analog audio design, the TL072 will undoubtedly be a valuable tool in your arsenal, enabling you to create high-quality, low-noise audio circuits with ease.