The LM358N is a dual operational amplifier (op-amp) from the manufacturer STMicroelectronics. The IC is commonly used in various analog applications, and its full pin function specifications are essential for designing circuits that involve amplification.
Below, I'll explain the pinout and the function of each pin in a detailed manner, covering all pins for this component. I'll provide you with the full pinout description for the standard 8-pin Dual Inline Package (DIP) form factor of the LM358 N. Since the LM358 N has 8 pins, I will thoroughly cover the function of each pin.
LM358N Pinout (8 Pins)
Pin Number Pin Name Pin Function Description 1 Offset Null This pin is used for offset voltage adjustment. You can connect a potentiometer between this pin and pin 5 (Offset Null) to nullify the input offset voltage of the op-amp. 2 Inverting Input (–) This is the inverting input of the operational amplifier. In most circuits, this pin is used for feedback from the output. It is often connected to a resistor in feedback configurations. 3 Non-Inverting Input (+) This is the non-inverting input of the op-amp. Signals applied to this pin are amplified and appear at the output without inversion. It is typically connected to the input signal in non-inverting amplifier configurations. 4 V– (Negative Supply) This is the negative power supply pin. For a single-supply configuration, this pin is connected to ground. For a dual-supply configuration, this pin is connected to the negative rail (usually −15V or similar). 5 Offset Null This pin, used in conjunction with pin 1, allows the offset voltage to be adjusted. A potentiometer connected between pins 1 and 5 helps to fine-tune the offset to minimize error in the amplifier’s performance. 6 Output This is the output pin where the amplified signal appears. The signal is taken from this pin after amplification based on the configuration of the surrounding circuit. 7 V+ (Positive Supply) This is the positive supply pin for the op-amp. For a single-supply configuration, this pin is connected to the positive voltage rail (typically +15V or similar). 8 NC (No Connection) This pin is not connected internally and is often reserved for future use or simply as a placeholder. It can be left unconnected in most applications.LM358N Pin Function FAQs (Frequently Asked Questions)
Q: What is the function of pin 1 on the LM358N? A: Pin 1 is the "Offset Null" pin, used to adjust the input offset voltage by connecting a potentiometer between pin 1 and pin 5.
Q: How can I adjust the offset voltage using the LM358N? A: You can adjust the offset voltage by connecting a potentiometer between pins 1 and 5 (Offset Null), then tweaking it to minimize the offset error.
Q: What does the inverting input (pin 2) of the LM358N do? A: Pin 2 is the inverting input, where the feedback from the output is typically applied. This input receives signals that are inverted in the output.
Q: What is the function of the non-inverting input (pin 3) of the LM358N? A: Pin 3 is the non-inverting input, where the input signal is applied and is amplified without inversion in the output.
Q: What does pin 4 (V–) connect to in a dual-supply configuration? A: Pin 4 (V–) connects to the negative power supply rail, typically to a negative voltage such as −15V in a dual-supply setup.
Q: Can pin 4 (V–) be connected to ground in a single-supply configuration? A: Yes, in a single-supply configuration, pin 4 (V–) is connected to ground.
Q: What happens if pin 5 (Offset Null) is left unconnected? A: Pin 5 should not be left unconnected if you need to adjust the offset voltage. If it is unconnected, the op-amp might exhibit offset errors in some circuits.
Q: What is the role of pin 6 (Output) on the LM358N? A: Pin 6 is the output pin where the amplified signal appears. It is where you connect the load or feedback network.
Q: What is the positive supply pin (pin 7) used for? A: Pin 7 (V+) connects to the positive power supply rail. For a single-supply configuration, it connects to the positive voltage (e.g., +15V).
Q: Does the LM358N have a shutdown pin? A: No, the LM358N does not have a dedicated shutdown pin. The op-amp can be turned off by removing the power supply voltage or grounding the supply pins.
Q: Can the LM358N be used with a single-supply voltage? A: Yes, the LM358N can operate with a single supply voltage, typically from +3V to +32V, with the negative supply (V–) connected to ground.
Q: What is the maximum output voltage swing for the LM358N? A: The output swing is typically between V– + 1V to V+ – 1V, depending on the load and supply voltage.
Q: Can the LM358N drive high-current loads directly? A: No, the LM358N is not designed to drive high-current loads directly. It is designed for low-power applications, and external transistor s or buffers are often used to drive higher-current loads.
Q: What is the maximum input voltage range for the LM358N? A: The input voltage range for the LM358N is typically from V– + 2V to V+ – 2V, ensuring the input stays within the common-mode range.
Q: Can I use the LM358N for high-speed circuits? A: The LM358N is not suitable for high-speed applications, as its bandwidth is relatively low. It is better suited for low-frequency amplification tasks.
Q: Is the LM358N suitable for audio applications? A: Yes, the LM358N can be used for audio applications where low power and moderate bandwidth are sufficient, such as in preamplifier circuits.
Q: How do I calculate the gain of an op-amp circuit using the LM358N? A: The gain of a non-inverting amplifier configuration is given by ( \text{Gain} = 1 + \frac{Rf}{R{in}} ), where ( Rf ) is the feedback resistor and ( R{in} ) is the resistor connected to the input.
Q: What is the input bias current for the LM358N? A: The LM358N has a typical input bias current of around 250nA, which is a low value suitable for most applications.
Q: How should I handle the LM358N if I need to use it in a temperature-sensitive application? A: The LM358N has a wide operating temperature range (typically -40°C to +85°C). However, if you need precise performance under varying temperatures, you may want to use an op-amp with a lower temperature coefficient.
Q: What is the output impedance of the LM358N? A: The output impedance of the LM358N is typically low (around 100Ω), making it suitable for driving most loads directly in many applications.
This explanation gives a complete understanding of the LM358N, including its pinout, detailed function descriptions, and a helpful FAQ for common usage scenarios.
