IC LM324N DIP14, Quadruple amplifier

The LM324N integrated circuit is a quadruple operational amplifier, that is, four independent high-gain operational amplifiers, integrated in the same DIP14 package. It is one of the most widely used analog circuits for signal amplification, active filters, comparators, voltage-to-current converters, oscillators, and interfacing between sensors and digital circuits, being used both in hobbyist projects and in industrial equipment.

Each of the four amplifiers has a unity-gain bandwidth of 1 MHz, internally frequency compensated, and can operate from a single supply between 3 and 32 VDC or from a dual supply between ±1.5 and ±16 VDC. The common-mode input voltage includes ground (GND), and the output can go down almost to ground even when the circuit is powered from a single supply, which eliminates the need for a separate negative supply. The current consumed by the entire circuit is low and practically independent of the supply voltage.

Among the main characteristics are an open-loop gain of approximately 100 dB, very low input bias current, the ability to configure each of the 4 channels as an amplifier, comparator, or active filter, and compatibility with all forms of digital logic. Power is supplied on pin 4 (V+) and pin 11 (GND), according to the standard DIP14 package.

Specifications:

Supply voltage: 3 - 32 VDC (single supply) or ±1.5 - ±16 VDC (dual supply)

Supply current: 0.7 mA typical, 1.2 mA maximum, at V+ = 5 V, for the entire circuit (4 amplifiers)

Number of amplifiers: 4, independent

Open-loop gain: approximately 100 dB

Unity-gain bandwidth: 1 MHz, temperature compensated

Slew rate: 0.5 V / us

Input offset voltage: 2 mV typical, 7 mV maximum

Input bias current: 45 nA typical, 250 nA maximum

CMRR (common-mode rejection): 65 - 85 dB

PSRR (supply variation rejection): 65 - 100 dB

Output current per channel: approximately 20 mA source, 10 mA sink, at V+ = 15 V

Operating temperature range: 0 - 70 C

Package: DIP14 (PDIP, 2.54 mm pin pitch)

Dimensions: 19.3 x 6.4 mm

Pinout:

Usage:

Identify pin 1 by the notch or the marked dot on the package and insert the circuit into the breadboard or socket with this orientation.

Power the circuit between pin 4 (V+) and pin 11 (GND) with a voltage between 3 and 32 VDC for single-supply operation, or connect V+ and V- relative to ground for dual-supply operation between ±1.5 and ±16 VDC.

Do not exceed the maximum voltage of 32 V between the supply pins and do not apply voltages more negative than ground to the inputs, to avoid opening the internal protection junctions.

Connect the signal to be amplified to the non-inverting or inverting input of the desired channel (for example pins 2 and 3 for the first amplifier) and set the desired gain with an external feedback network made of resistors between the output and the inverting input.

Use each of the 4 amplifiers independently, connecting unused inputs to a defined voltage level, to avoid oscillations or unnecessary extra current consumption.

Add a 100 nF decoupling capacitor as close as possible to pin 4, between V+ and GND, for stability in the presence of supply noise.

Keep in mind that the output of each amplifier can only reach about 1.5 V below V+ and cannot drop completely to 0 V when sourcing current; this behavior is normal for this type of amplifier.

For quick test setups, use the circuit in a comparator configuration or as a simple non-inverting amplifier before moving on to more complex schematics.