LM324N Internal Structure, Working Principle and LM324 vs LM324N
18 March 2024
Ⅱ. Internal structure and working principle of LM324N
Ⅲ. Typical performance characteristics of LM324N
Ⅳ. How to configure the power supply for LM324N?
Ⅵ. How to use LM324N to amplify DC voltage?
Ⅶ. What is the difference between LM324 and LM324N?
The LM324N is a high-gain voltage amplifier with differential input and single-ended output. It has high performance and a wide power supply voltage range, and also has features such as anti-reverse power supply protection and over-voltage protection. These features effectively improve the reliability of the circuit. This article will introduce the specific information of LM324N in detail, including its internal structure, working principle, etc., and attach a pin diagram for reference.
LM324N is a general-purpose operational amplifier chip widely used in analog signal processing and amplification circuits. It features four independent operational amplifiers capable of amplifying and processing various analog signals. The chip has a total of 14 pins, its operating temperature range is from -40°C to +85°C, and the package type is DIP. The main function of LM324N is to amplify, filter, compare and operate input signals. The output results can be further processed as needed or used to drive other circuits. LM324N finds widespread application in electronic equipment, serving purposes ranging from constructing comparators, filters, and sensor signal conditioning circuits to facilitating audio amplification and oscillator functionality.
Alternatives and equivalents:
• CA0324E
• LM2902NG
• LM324NE3
LM324N uses bipolar transistor and field-effect transistor technology. Its internal structure mainly includes modules such as multi-stage differential amplifiers, cascaded common-mode amplifiers, voltage reference sources, current sources, and output stages. These modules cooperate with each other to realize the complex signal amplification and conditioning functions of LM324N.
LM324N achieves amplification and gain adjustment of input signals by cascading multi-stage transistors. At the same time, it also has an internal voltage reference source and current limiting circuit, allowing it to operate over a wide supply voltage range and provide high-stability operation.
The LM339N can be connected to either a single power supply (3 to 30V) or a dual power supply (±1.5 to ±15V). It features low drive power consumption and is compatible with TTL logic circuits.
1. Single-supply power supply: You can provide the LM324N with a DC power supply between 3V and 30V. In this case, you need to connect the negative terminal of the power supply to the ground (GND) pin of the IC.
2. Dual power supply: Another way of supplying power is to use a dual power supply with a supply voltage ranging from ±1.5V to ±15V. In this type of power supply, it requires two power supplies, one positive and one negative, and both of them need to be connected to the ground (GND) pin of the IC.
When configuring the power supply, we need to pay attention to the following points:
• Overload protection: To avoid overloading the power supply, we should make sure that the current output capability of the power supply meets the needs of the LM324N.
• Power supply stability: In order to ensure the normal operation of the LM324N, the supplied power supply should be kept stable to avoid excessive voltage fluctuations.
• Power supply ripple: Excessive power supply ripple may adversely affect the performance of LM324N. Therefore, if conditions permit, we should minimize the power supply ripple as much as possible.
The LM324N has a total of 14 pins, the specific pin arrangement is as follows.
• VCC+: This is the positive power supply pin, usually accessing the positive voltage, generally 5V or 9V.
• VCC-: This is the negative power supply pin, usually access the negative voltage, generally -5V or -9V.
• lN1, IN2, IN3, IN4: These are input pins for signals to be amplified. They can accept a range of voltages from negative to positive supply.
• OUT1, OUT2, OUT3, OUT4: These are output pins for outputting the amplified signal.
• GND: These are ground pins and are used to connect the ground in the circuit together.
First, it needs to be clarified that the amplification range of the LM324N is between 25000 (minimum) and 100000 (typ). Therefore, it cannot directly operate at excessive voltage. To work in that kind of circuit, we need to set certain conditions (such as a certain voltage threshold). When these conditions are met, we can control the relay or thyristor component to turn on the 220V voltage; when the conditions are not met, we can control the relay to cut off the 220V voltage. This process can be completed through comparators to complete conditional judgment. Since the output current of the comparator or LM324N is not enough to directly control the action of the relay, we need to use their output to drive the transistor, and then the transistor controls the switching of the relay.
When using an operational amplifier DC signal, due to the characteristics of the DC signal and the characteristics of the operational amplifier itself, the circuit and operational amplifier have the following requirements:
1. The op amp cannot be powered by a single power supply. It must use dual power supplies and the voltage should be stabilized.
2. Since the operational amplifier has its own offset voltage, we should add a zero-adjustment circuit and a temperature drift compensation circuit during DC amplification.
3. When amplifying DC signals, the drift and unbalanced voltage of the operational amplifier itself cannot be ignored, so we'd better use a high-precision operational amplifier (such as UA741).
The LM324 and LM324N are functionally identical. The LM324 is not explicitly specified in terms of package, whereas the LM324N comes in a plastic dual in-line package. The LM324 is a large class of quad operational amplifiers. The LM324N is one of the many subtypes (specifications) that exist depending on their suffixes. If not specified, a single reference to the LM324 is usually considered to be equivalent to the LM324N, which is the LM324 in the DIP14 package (the most common type).
The LM324 series devices are quad operational amplifiers with true differential inputs. They offer some significant advantages over standard operational amplifiers for single-supply applications. These quad amplifiers can be operated from supplies as low as 3.0 volts or as high as 32 volts with one-fifth the quiescent current of the MC1741. The common-mode input range includes negative supplies, so they eliminate the need for external biasing components in many applications.
Frequently Asked Questions
1. What is the slew rate of LM324N?
The slew rate per the LM324 data sheet is 400 mV/µs when the given parameters are implemented.
2. What is the input voltage range of LM324N?
The LM324N has an input voltage range of 0 to V+-1.5 V. So the upper limit of the inputs with 5 V supply is 3.5 V. Your 4.3 and 5 V inputs are above this limit, so the OP amp will not work as you intend.
3. What is the offset voltage of LM324N?
Lastly, the offset voltage is a good design parameter to know. For the LM324 the typical value is 2mV while the maximum is 9mV at extreme temperatures. For design, the 9mV value should be used to include worst case scenarios.
4. What is the function of LM324N?
Conventional operational amplifier applications can be easily implemented with the LM324N. It has four independent op-amps compensated in a single 14-pin DIP package that can be used as amplifiers, comparators, oscillators, rectifiers, etc. We use these in our Interactive LED Panel kits.
