Part of the Day · LM324 — SOIC-14 quad op amp

Part of the Day · 2026-11-02

The most common general-purpose amplifier, with four op amps in one chip. It runs from a single supply and its input range extends down to GND, so it is widely used for sensor signal amplification, filters and voltage monitoring. It is roughly like two LM358s in one package.

Actual size

↓ Actual size, left edge aligned to 0 on the ruler

One ruler tick = 1mm. On PC this is actual size on a 24-inch FHD monitor at 100% zoom; on iPhone it adjusts automatically. For other screens, use “Calibrate ruler” below.

Enlarged (SOIC-14 · top view · approx. 12×)

Pins 1 1OUT (output 1) · 2 1IN− (inverting input 1) · 3 1IN+ (non-inverting input 1) · 4 VCC+ (supply) · 5 2IN+ (non-inverting input 2) · 6 2IN− (inverting input 2) · 7 2OUT (output 2) · 8 3OUT (output 3) · 9 3IN− (inverting input 3) · 10 3IN+ (non-inverting input 3) · 11 VCC− (GND or negative supply) · 12 4IN+ (non-inverting input 4) · 13 4IN− (inverting input 4) · 14 4OUT (output 4)

Package SOIC-14

Key specifications

Values are from the Texas Instruments datasheet.

Marking and pins

Typical uses

• Sensor / current-sense signal amplification (single supply)
• Active filters and buffers — four circuits in one chip to cut part count
• Feedback amplifier and voltage monitoring in power supply, charger and inverter circuits
• Control circuits in home appliances such as air conditioners, washers and refrigerators

Companion & similar parts

• LM324B — Newer version from the same datasheet — 3 ~ 36V, offset max 3mV, 240µA per amplifier, drop-in replacement for the original LM324
• LM324A — Same pinout, selected for tighter offset (max 3mV)
• LM2902 — Same pinout, -40 ~ 125℃ temperature range (supply 3 ~ 26V)
• LM358 — Dual (8-pin) op amp of the same family

The supply pins sit in the middle (pin 4 VCC+, pin 11 VCC−), which differs from the 8-pin LM358. The LM339 comparator is also 14-pin, but its pinout and output type are different, so it cannot be swapped in directly. The output high level does not reach VCC+; it goes to about VCC − 1.5V (2kΩ load, 25℃ — not rail-to-rail). When substituting, check the suffix too (A, B, BA, K).