LM324AN/NOPB - Quad 1 MHz General-Purpose Op Amp | Texas Instruments
Teilenummer: LM324AN/NOPB ✓ AktivLM324AN/NOPB Übersicht
An operational amplifier (op amp) is a high-gain differential amplifier whose inverting and non-inverting inputs are compared and amplified. When negative feedback is applied, the closed-loop gain is set entirely by external resistors, which makes the op amp the basic building block of the analog signal chain: it sits in the hierarchy above discrete transistor gain stages and below complete application circuits such as amplifiers, filters, comparators, transducers and line drivers. The LM324 family, introduced by National Semiconductor and now a Texas Instruments product, is the archetypal single-supply general-purpose quad.
The LM324A device in the LM324AN/NOPB provides a typical input offset voltage of 2 mV, an input bias current of 250 nA, and a typical supply current of 0.8 mA per amplifier, so four channels consume roughly 3.2 mA at 5 V. Output swing reaches within 20 mV of the negative rail and about 100 mV below the positive rail at 100 kΩ load, while the output can source or sink tens of milliamperes. Internal differential input and output protection diodes tolerate rail-to-rail input transients.
The architecture is a classic bipolar, voltage-feedback design with a single dominant-pole compensation network per channel, giving unity-gain stability without external compensation. Noise is dominated by input-referred voltage noise of roughly 45 nV/√Hz at 1 kHz, and the amplifiers are designed for unity-gain operation in comparators, buffers and general analog signal conditioning.
Typical applications include low-cost sensor signal conditioning, 4-20 mA current-loop receivers, audio mixer subcircuits, active filters, temperature controllers, bridge amplifier front ends, power-supply feedback loops and general instrumentation. Because the package is a through-hole PDIP-14, the part also fits legacy industrial and educational control boards that were designed around the original LM324 footprint.
A key design consideration is that the LM324 does not rail-to-rail output and its common-mode input range excludes the positive rail, so headroom must be planned for single-supply designs. The input bias current flows through the source resistance, so matched resistor networks keep output offset small. Using the device as a comparator requires care because output saturation recovery takes several microseconds.
This page adds information the datasheet does not provide: a drop-in alternative matrix with quantified differences, package and pinout reference, engineering design notes covering decoupling and input common-mode limits, and a parameter-by-parameter comparison table for selecting between the Texas Instruments, onsemi and equivalent quad op amp sources.
Drop-in-Alternativen für LM324AN/NOPB – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Varianten dieser Serie
Modelle derselben Serie, die drop-in-kompatibel sind mit LM324AN/NOPB (gleiche Bauform und Footprint) – abweichend in Supply Configuration, Mounting Type, Package, Amplifier Count, Amplifier Type.
LM324AN
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →LM324N/NOPB
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
LMC660CN
✅ Drop-In ⚠️ Spezifikationen ungeprüft📋 Referenzalternative (nicht im Katalog)
LM324AN
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →LM324N
✅ Drop-InPreis auf Anfrage
Datenblatt ansehen →LM324AN/NOPB Grenzwerte & elektrische Eigenschaften
| Number of Amplifiers | 4 |
| Amplifier Type | General Purpose, Voltage Feedback, Single Supply |
| Gehäuse | 14-PDIP (N package), through-hole |
| Supply Voltage Range (LM324A) | 3 V to 30 V |
| Supply Voltage Range (LM324B / LM324BA, next generation) | 3 V to 36 V |
| Open-Loop Gain (Typical) | 100 dB |
| Gain-Bandwidth Product | 1.0 MHz |
| Slew Rate | 0.5 V/us |
| Input Offset Voltage (LM324A, Typical) | 2 mV |
| Input Bias Current (Typical) | 250 nA |
| Supply Current per Amplifier (Typical) | 0.8 mA |
| Output Current (Typical, Source/Sink) | 20 mA / 10 mA |
| Output Swing (100 kOhm Load) | Within 20 mV of negative rail, 100 mV below positive rail |
| Input Common-Mode Voltage Range | 0 V to (V+) - 1.5 V |
| Input Noise Voltage Density at 1 kHz | 45 nV/√Hz |
| Operating Temperature Range (N Grade) | 0 °C to +70 °C |
| Montageart | Through-hole (THT) |
| RoHS-Status | Compliant (RoHS / NOPB lead-free finish) |
| Compensation | Internal (internally frequency compensated) |
LM324AN/NOPB Pin-Konfiguration
| Pin 1 | OUT1 — Output of amplifier 1 |
| Pin 2 | IN1- — Inverting input of amplifier 1 |
| Pin 3 | IN1+ — Non-inverting input of amplifier 1 |
| Pin 4 | V+ — Positive supply voltage |
| Pin 5 | IN2+ — Non-inverting input of amplifier 2 |
| Pin 6 | IN2- — Inverting input of amplifier 2 |
| Pin 7 | OUT2 — Output of amplifier 2 |
| Pin 8 | OUT3 — Output of amplifier 3 |
| Pin 9 | IN3- — Inverting input of amplifier 3 |
| Pin 10 | IN3+ — Non-inverting input of amplifier 3 |
| Pin 11 | V- — Negative supply voltage (ground in single-supply use) |
| Pin 12 | IN4+ — Non-inverting input of amplifier 4 |
| Pin 13 | IN4- — Inverting input of amplifier 4 |
| Pin 14 | OUT4 — Output of amplifier 4 |
Typische Anwendungen
LM324AN/NOPB ist geeignet für 6 Anwendungs: Industrial Sensor Signal Conditioning, Audio Mixer and Summing Amplifier, Power Supply Feedback and Control Loops, Active Filters and Oscillators, Automotive and Heavy Equipment Control (Commercial Grade), Test and Measurement Buffering.
Industrial Sensor Signal Conditioning
The LM324AN/NOPB is a natural fit for conditioning 4-20 mA loop and resistive bridge sensor signals in industrial transmitters. Its 250 nA typical input bias current produces only 25 mV of error across a 100 kOhm source, and the 2 mV typical input offset voltage keeps the amplifier's own error well below the 1% loop accuracy usually required. With 100 dB typical open-loop gain and a 1.0 MHz gain-bandwidth product, a non-inverting stage gains 100 with a 6.28 dB closed-loop bandwidth, enough to settle quickly on a 4 Hz process signal. The 3 V to 30 V supply range lets the same part run from a 24 V loop supply, while the 14-pin PDIP footprint suits legacy 4-20 mA panel meters and controller boards that were laid out around the original LM324 socket.
Empfohlen
Audio Mixer and Summing Amplifier
In small audio mixers and headphone-buffer boards, the LM324AN/NOPB supplies four independent channels at very low cost. Each channel drives a resistive summing network that inverts and combines several line-level inputs, and the 0.5 V/us slew rate keeps distortion acceptable at audio frequencies when the closed-loop gain is kept below about 10. Output current of roughly 20 mA source and 10 mA sink is enough to feed a 10 kOhm volume-control potentiometer and follow-on circuitry, and the internal differential protection diodes guard the inputs against hot-plugging a live cable. Because bipolar input bias current is roughly 1000x higher than a CMOS audio op amp, keep the summing resistors below about 100 kOhm to avoid channel-to-channel DC mismatch and audible thumps during switching.
Empfohlen
Power Supply Feedback and Control Loops
The LM324AN/NOPB is frequently used inside linear regulators and DC-DC controllers as the error amplifier and feedback element. The high 100 dB typical open-loop gain gives a wide loop gain for tight line and load regulation, while the 0.8 mA per-amplifier supply current is negligible against the tens of milliampes typically drawn by a power stage. Its wide 3 V to 30 V supply rating lets the error amplifier sit directly across the raw input bus without level shifting. The main constraint is output swing, since the output cannot reach the positive rail, so leave at least 100 mV of headroom at the top of the feedback divider. The same device also serves as a soft-start comparator input and a current-mode control loop in linear and buck-boost topologies.
Empfohlen
Active Filters and Oscillators
For low-frequency active filter and oscillator designs in the audio and instrumentation band, the LM324AN/NOPB provides the gain and bandwidth needed in a multi-stage topology. A second-order Sallen-Key low-pass built around this device can realise a 1 kHz corner with closed-loop gains of about 10 while retaining roughly 100 kHz of closed-loop bandwidth, so phase error stays small at the corner frequency. Because the device is internally frequency compensated and unity-gain stable, no external compensation network is required, which simplifies cascaded filter design. Keep the resistor values near 10 kOhm to 100 kOhm so that the 250 nA input bias current contributes negligibly, and observe the input common-mode ceiling of roughly V+ minus 1.5 V when biasing a filter around a mid-supply reference.
Empfohlen
Automotive and Heavy Equipment Control (Commercial Grade)
The LM324AN/NOPB is widely used in legacy agricultural, construction and machine-control equipment for actuator drivers, valve amplifiers and simple PID loops. Its 3 V to 30 V supply range covers both 12 V and 24 V vehicle rails without a separate regulator, and the 14-pin PDIP package is mechanically robust on through-hole boards that see vibration and large temperature swings. Because the LM324AN is the commercial 0 °C to +70 °C grade, industrial designs operating outside that window should specify the wider industrial or automotive temperature variant with the same 14-pin footprint. Always confirm the AEC-Q100 qualification status of the exact ordered part number, since the standard LM324AN is not an automotive-qualified device, and use the enable and protection paths around it to handle load dump and reverse-battery transients.
Empfohlen
Test and Measurement Buffering
In bench instruments and low-cost data acquisition cards, the LM324AN/NOPB is commonly used as a unity-gain buffer between a resistive divider, sensor or multiplexer and the following stage. The 100 dB typical open-loop gain makes the closed-loop follower essentially ideal, and the 1.0 MHz bandwidth limits settling behaviour rather than DC accuracy. As a buffer it also provides current gain, moving the burden of driving the measurement chain off the source so that it does not distort the reading. Care is needed at the input: the common-mode range does not include the positive rail, so a 5 V supply limits usable inputs to about 3.5 V, and the bipolar input bias current produces an offset of tens of millivolts in high-impedance dividers. Add an RC anti-alias filter at the buffer output and use the Request a Quote form on this page for lead time on volume quantities.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für LM324AN/NOPB – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | LM324AN | LM324N/NOPB | LMC660CN | LM324AN | LM324N |
|---|---|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | onsemi | onsemi |
| Package | 14-PDIP (N package) | 14-PDIP - same footprint | 14-PDIP - same footprint | 14-PDIP - same footprint | 14-MDIP - same footprint | 14-PDIP - same footprint |
| Number of Amplifiers | 4 | 4 | 4 | 4 | 4 | 4 |
Wichtigste Unterscheidungsmerkmale
- Offset accuracy of the A grade over the standard N grade (vs. LM324N/NOPB)
- Lower supply current per amplifier for battery and loop-powered designs (vs. LMC660CN)
- Same 14-PDIP footprint across two manufacturers for true second sourcing (vs. onsemi LM324AN)
- Wide supply range for direct 24 V industrial bus operation (vs. LM324N/NOPB)
- Leakage-free lead-free assembly suffix for RoHS-compliant production (vs. LM324AN (TI, non-NOPB orderable))
Designhinweise
Estimated: with a 5 V single supply at 1 V output and 10 mA load, each LM324 amplifier dissipates roughly (5 V - 1 V) x 10 mA = 40 mW, so the full quad dissipates about 160 mW. At a 24 V industrial supply the same current gives an estimated 230 mW per amplifier, or 920 mW for the quad, which is the main reason the supply-current-per-amplifier figure (0.8 mA typical) matters more than absolute quiescent current in most designs. Tie pin 11 to the system ground and connect a 0.1 uF ceramic plus a 10 uF bulk capacitor between pin 4 and pin 11, placing them at the package pins.
The LM324 does not include input common-mode range down to the negative rail in bipolar single-supply use, and it cannot swing its output to the positive rail. The usable common-mode input range extends to roughly V+ minus 1.5 V, and the output can only reach about 100 mV below V+. A common mistake is designing a 5 V rail-to-rail input amplifier around the LM324 and finding that signals near 4.5 V clip at the input stage. Also note that the input bias current of 250 nA flows through the source impedance, so a 1 MOhm source creates a 250 mV error; keep source impedances below about 100 kOhm or add a bias compensation resistor equal to the parallel combination of the feedback network.
Keep the four channels separated on the board because each pair of inverting and non-inverting inputs is a high-impedance node that can couple between channels. Route each feedback resistor directly between its own output pin and inverting input pin, and place the non-inverting input connection away from the supply routing and from the pin 11 ground return path. Use a solid ground plane with the socket ground pins 11 tied straight down to it rather than through a long trace, since a shared impedance in the ground return converts supply noise into input-referred noise at the summing junction.
When the LM324 is used as a comparator, the output saturates and requires several microseconds to leave saturation, which produces false triggers and long recovery times near the threshold. For low-frequency slow threshold detection this is acceptable, but it is the dominant reason the part is not recommended for zero-crossing or fast overvoltage detection. Add positive feedback (hysteresis) of roughly 10 mV to 50 mV on the non-inverting input to reject noise, and use a dedicated comparator for signals crossing the threshold faster than a few microseconds.
A bipolar input stage like the LM324 can pick up audible hum and mains-related interference when connected to high-impedance sources, especially with long unshielded leads. Keep the input network close to the package, shield the source where possible, and set the closed-loop bandwidth to the lowest value that meets the system response requirement by choosing closed-loop gains that do not exceed roughly 100 with the 1.0 MHz gain-bandwidth product. Avoid leaving an unused amplifier channel with an open input; tie its inputs to ground or to a defined bias point to avoid oscillation and radiated noise.
Compliance-Informationen
The /NOPB suffix identifies the lead-free (no Pb) assembly and the manufacturer markets the LM324 family as RoHS compliant. The LM324AN is the commercial 0 °C to +70 °C N grade and is not AEC-Q100 qualified; REACH, halogen-free and conflict-minerals statements were not confirmed in the information consulted and are listed as unknown.
