LM324 PCB Design Guide: Footprint, Pinout, and Alternatives
Jellybean quad single-supply op amp: 3 V to 32 V, input range includes ground.
The LM324 is the jellybean quad op amp: four internally compensated amplifiers in one 14-pin package, designed to run from a single supply anywhere between 3 V and 32 V (or ±1.5 V to ±16 V dual), with an input common-mode range that includes ground and a supply current of 0.7 mA typical for all four amplifiers at 5 V. Unity-gain bandwidth is 1 MHz and temperature compensated. Decades of ubiquity mean every distributor stocks it, every simulator models it, and every second-hand schematic on the internet assumes it.
Pick it for slow, cheap, single-supply analog: sensor front ends that sit near ground, modest active filters, threshold and glue circuits where 2 mV typ / 7 mV max input offset and 45 nA of input bias current (flowing out of the pins — the input stage is PNP) are good enough. Do not pick it where the signal must live near the positive rail, where the output has to actively sink current at ground, where an AC-coupled load needs clean zero crossings, or on boards that see temperatures below 0 °C, where the LM324-N grade simply ends. Those jobs belong to the LM2902-N or a rail-to-rail CMOS quad; see the alternatives.
The recurring board-level failures are the same five every generation of engineers rediscovers: crossover distortion on capacitively coupled loads, an output that can sink only microamps near ground, the 1.5 V dead band below V+ on both inputs and output, phase reversal when an input dips below −0.3 V, and the temperature-grade and short-circuit limits that only show up in the field. Each is covered below.
What breaks boards
AC-coupled loads get crossover distortion by design
The output stage idles in class A for small signals and converts to class B for large ones, and the output must rise approximately 1 diode drop above ground before the on-chip PNP can sink current. Capacitively couple the load — audio into a coupling cap, an AC signal into the next stage — and every zero crossing picks up a dead zone. TI's own fix is a resistor from the output to ground to raise the class A bias current; directly coupled DC loads show no crossover distortion. Capacitive loads on the output also cut stability margin: 50 pF is the worst-case unity-gain figure, so isolate larger caps resistively.
Near ground, the output can sink only microamps
The headline feature — output swings to ground on a single supply — only holds when the load pulls the pin down. Sink capability collapses near 0 V: 12 µA min / 50 µA typ at VO = 200 mV (V+ = 15 V), versus 10 mA min / 20 mA typ once the output sits at 2 V. With a resistive load to ground, VOL is a genuine 5 mV typ / 20 mV max (V+ = 5 V, RL = 10 kΩ); with a load sourcing current into the pin, the output stalls above ground. Add a pull-down if the output must actively pull low.
Nothing works within 1.5 V of V+
The input common-mode range runs from 0 to V+ − 1.5 V at 25 °C and shrinks to V+ − 2 V over temperature, and the output tops out well below the rail too: VOH is 26 V min with a 2 kΩ load at V+ = 30 V. On a low single supply that dead band is a big fraction of the range, and it bites hardest when the part is pressed into comparator duty on signals near the positive rail or buffering a sensor that swings to its supply. The LM324 is excellent at ground — that is its design point — and blind near V+.
An input below −0.3 V can slam the output to V+
Absolute-minimum input voltage is −0.3 V. Below that, the input PNP's collector-base junction forward-biases and lateral NPN parasitic action can force op-amp outputs to the V+ level (or to ground for a large overdrive) for the duration — the classic phase reversal. It is not destructive if input current stays inside the 50 mA rating, and normal operation returns above −0.3 V, but a control loop watching that output will not care. AC-coupled inputs, inductive sensors, and signals present before the supply are the usual sources; clamp with a diode and a series resistor into the input pin.
0 °C to 70 °C grade, and shorts are only safe below 15 V
The LM324-N's operating junction temperature range is 0 °C to 70 °C — outdoor and automotive boards are out of grade; RθJA is 88 °C/W in the 14-pin SOIC against a 125 °C junction limit. The LM2902-N is the same die rated −40 °C to +85 °C, traded for a 26 V abs max instead of 32 V. Output shorts to ground run about 40 mA regardless of V+ and are rated continuous only for one amplifier with V+ ≤ 15 V at 25 °C; above 15 V, or with multiple outputs shorted at once, dissipation exceeds ratings and the part dies. Shorts to V+ are destructive, full stop.
Key specifications
| Parameter | Value | Source |
|---|---|---|
| Supply range | 3 V min to 32 V max (V+ - V-) for LM324-N; Features state single supply 3 V to 32 V or dual supplies +/-1.5 V to +/-16 V | SNOSC16D Rev D, Section 6.3 Recommended Operating Conditions + Section 1 Features |
| Supply current | 0.7 mA typ / 1.2 mA max (V+ = 5 V); 1.5 mA typ / 3 mA max over full temperature range (RL = infinity on all op amps, V+ = 30 V) | SNOSC16D Rev D, Section 6.6 Electrical Characteristics: LM124-N/224-N/324-N/2902-N, supply current rows (LM324-N column) |
| Input offset voltage | 2 mV typ / 7 mV max (TA = 25 C); 9 mV max over full temperature range (0 C to +70 C for LM324-N) | SNOSC16D Rev D, Section 6.6 Electrical Characteristics, input offset voltage rows (LM324-N column) + note 1 temperature limits |
| Input bias current | 45 nA typ / 250 nA max (IIN(+) or IIN(-), VCM = 0 V, TA = 25 C); 40 nA typ / 500 nA max over temperature; current flows out of the IC (PNP input stage) | SNOSC16D Rev D, Section 6.6 Electrical Characteristics, input bias current rows (LM324-N column) + note 3 |
| Unity-gain bandwidth | 1 MHz (temperature compensated) | SNOSC16D Rev D, Section 1 Features ('Wide Bandwidth (Unity Gain) 1 MHz') |
| Input common-mode range | 0 to V+ - 1.5 V (V+ = 30 V, TA = 25 C); 0 to V+ - 2 V over full temperature range - includes ground on a single supply | SNOSC16D Rev D, Section 6.6 Electrical Characteristics, input common-mode voltage range rows (LM324-N column) |
| Output swing / near-ground sink | VOH 26 V min (RL = 2 kOhm) / 27 V min, 28 V typ (RL = 10 kOhm) at V+ = 30 V, i.e. output tops out well below V+; VOL 5 mV typ / 20 mV max (V+ = 5 V, RL = 10 kOhm); output sink capability near ground is only 12 uA min / 50 uA typ (VIN- = 1 V, VIN+ = 0 V, V+ = 15 V, VO = 200 mV, TA = 25 C) vs 10 mA min / 20 mA typ sink at VO = 2 V | SNOSC16D Rev D, Section 6.6 Electrical Characteristics (continued), Output Voltage Swing and Output Current rows (LM324-N column) |
| Absolute maximum ratings | Supply voltage 32 V; differential input voltage 32 V; input voltage -0.3 V to 32 V; input current 50 mA (VIN < -0.3 V) - the three voltage limits are 26 V for LM2902-N; driving any input below -0.3 V forward-biases the input PNP's collector-base junction and triggers lateral NPN parasitic transistor action that can force op-amp outputs to the V+ level (or to ground for a large overdrive) for the duration of the overdrive; not destructive, and normal output states re-establish when the input returns above -0.3 V (at 25 C); an input clamp diode with a resistor to the IC input terminal can be used | SNOSC16D Rev D, Section 6.1 Absolute Maximum Ratings table + note 3 + Section 7.4 Device Functional Modes |
| Output short-circuit to GND | Continuous rating applies to one amplifier with V+ <= 15 V and TA = 25 C; short-circuit output current to ground is approximately 40 mA independent of the magnitude of V+; at supply voltages in excess of 15 V, continuous short-circuits can exceed the power dissipation ratings and cause eventual destruction; destructive dissipation can result from simultaneous shorts on all amplifiers; shorts from the output to V+ can cause excessive heating and eventual destruction | SNOSC16D Rev D, Section 6.1 Absolute Maximum Ratings, Output Short-Circuit to GND row + note 5 |
| Operating temperature / thermal | Operating junction temperature 0 C to 70 C for LM324-N/LM324A (LM2902-N: -40 C to 85 C; LM224-N: -25 C to 85 C); RthetaJA 88 C/W for the 14-pin D (SOIC) package; at high temperatures derate based on a 125 C maximum junction temperature and 88 C/W, device soldered in a PCB operating in still air | SNOSC16D Rev D, Section 6.3 Recommended Operating Conditions + Section 6.4 Thermal Information + Section 6.1 note 4 |
| Output stage / crossover / capacitive loads | Output stage is class A for small signal levels and converts to class B in a large signal mode; the output voltage needs to raise approximately 1 diode drop above ground to bias the on-chip PNP transistor for output current sinking; for AC applications where the load is capacitively coupled, a resistor from the output to ground should be used to increase the class A bias current and prevent crossover distortion (where the load is directly coupled, as in DC applications, there is no crossover distortion); capacitive loads applied directly to the output reduce the loop stability margin - values of 50 pF can be accommodated using the worst-case non-inverting unity gain connection, large closed-loop gains or resistive isolation should be used for larger load capacitance | SNOSC16D Rev D, Section 7.4 Device Functional Modes |
| DC voltage gain / architecture | Large DC voltage gain 100 dB; four independent, high-gain, internally frequency compensated operational amplifiers designed to operate from a single power supply over a wide range of voltages; the low-power supply current drain is independent of the magnitude of the power supply voltage | SNOSC16D Rev D, Section 1 Features ('Large DC Voltage Gain 100 dB', 'Internally Frequency Compensated for Unity Gain') + Section 3 Description |
Verified against the manufacturer datasheet on 2026-07-10. Confirm the current revision before production use.
Alternatives
- LM324A: the tighter offset grade in the same datasheet: 2 mV typ / 3 mV max input offset at 25 °C versus 7 mV max for the base part, same package options. The cheap fix when offset is the only problem.
- LM2902-N: the same die specified for −40 °C to +85 °C instead of 0 °C to 70 °C, traded against a 26 V abs-max supply and input rating instead of 32 V. An automotive-qualified LM2902-Q1 is listed in the addendum.
- LM358: the dual (2-channel) member of the same single-supply op-amp family, for when only two amplifiers are needed.
- MCP6004: Microchip's quad CMOS op amp with rail-to-rail output, the common pick where the LM324's V+ − 1.5 V output headroom and microamp near-ground sink are a problem.
Common questions
- Can the LM324 run from a single 5 V supply?
- Yes — that is its design point. It is specified from 3 V to 32 V on a single supply (or ±1.5 V to ±16 V dual), the input common-mode range includes ground, and supply current is 0.7 mA typ / 1.2 mA max at 5 V. The catch on a 5 V rail is the top end: the input common-mode range stops 1.5 V below V+ (2 V over temperature) and the output cannot reach the rail either.
- Is the LM324 rail-to-rail?
- No. The input common-mode range is 0 to V+ − 1.5 V at 25 °C (V+ − 2 V over temperature): it includes ground, not the top rail. The output also tops out well below V+ (VOH 26 V min with a 2 kΩ load at V+ = 30 V), and while it swings to ground with a resistive load (VOL 5 mV typ / 20 mV max at 5 V, RL = 10 kΩ), it can only sink 12 µA min / 50 µA typ near 0 V.
- What is the difference between the LM324 and the LM358?
- Channel count. The LM358 is the dual (2-channel) member of the same single-supply op-amp family; the LM324 gives you four amplifiers in a 14-pin package. Pick the LM358 when two channels are enough and board space matters.
- What is the difference between the LM324 and the LM2902?
- Temperature grade and ratings. The LM2902-N is the same die in the same datasheet with a −40 °C to +85 °C operating junction temperature range (the LM324-N is 0 °C to 70 °C) and a 26 V abs-max supply and input rating instead of 32 V. For anything outdoors or in a vehicle, the LM324-N is out of grade; use the LM2902-N, or the LM2902-Q1 for automotive qualification.