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SOP-14 / DIP-14 · LM324
ActiveQuad Operational Amplifier
LM324
Texas Instruments · SOP-14 / DIP-14 · Quad Operational Amplifier
Price on Request
Get a competitive quote within 24 hours. Volume discounts available. Shenzhen stock ships in 1-2 business days.
Overview
The LM324 has been the default quad operational amplifier for more than four decades, and it still ships in the hundreds of millions every year. Four independent, internally frequency-compensated, unity-gain-stable amplifiers share a single 14-pin DIP, SOIC or TSSOP outline, which lets one part cover a four-channel sensor front end, a triple filter plus a comparator, or four separate DC gain blocks. Total supply current for all four amplifiers is only 0.7 mA typical (1.2 mA maximum), so the part is comfortable in battery-powered instruments that would otherwise need four discrete op-amps and a negative rail.
Electrical behaviour is well documented and predictable. Gain-bandwidth product is 1.2 MHz with a 0.5 V/µs slew rate, input offset voltage is 3 mV typical and 7 mV maximum at 25 °C (9 mV over the 0 °C to 70 °C range), input bias current is 20 nA to 250 nA, and input voltage noise density is 35 nV/√Hz. The defining feature remains the common-mode input range of 0 V to VCC − 1.5 V: because it includes the negative rail, low-side shunt sensing works directly from a single supply. The output swings to within 5 mV to 20 mV of ground when sinking current, but needs about 1.5 V of headroom to the positive rail, so the LM324 is not rail-to-rail. Output current is 20 mA to 30 mA sourcing and 10 mA to 20 mA sinking, with ±40 mA short-circuit capability.
For buyers the LM324 is one of the safest parts in the catalogue. TI produces the LM324, LM324A, LM324B and LM324BA grades, and the pin-compatible LM2902 extends the temperature range to −40 °C to +125 °C; STMicroelectronics, onsemi, UTC and many Asian fabs supply second sources that are functionally interchangeable. The newer LM324B and LM2902B grades raise the supply ceiling to 36 V, cut offset to 3 mV maximum, add integrated EMI/RF filtering and are drop-in replacements for legacy sockets. Shenzhen stock is deep and stable, MOQ is typically 1 reel (2,500 pcs SOIC-14) or 100 pcs loose for prototyping, and lead time is 1-2 days from local inventory. Counterfeit risk is low but not zero: inspect laser-etched marking, verify the date code with the manufacturer, and measure input offset on a sample if the lot came through a broker rather than an authorized distributor.
Key Features
- Four independent unity-gain-stable amplifiers in one 14-pin package
- Single-supply operation from 3 V to 32 V with input range down to ground
- Low supply current: 0.7 mA typical for all four amplifiers
- 1.2 MHz gain-bandwidth product, 0.5 V/µs slew rate, 35 nV/√Hz noise
- Second-sourced by TI, ST, onsemi and Asian fabs with identical pinout
Typical Applications
- Sensor signal conditioning and four-channel data acquisition front ends
- Low-side current shunt amplification in chargers, motor drives and PSUs
- Active filters, integrators and DC gain blocks in industrial controls
- Window comparators and threshold detectors with external references
- White goods, power supplies and building automation boards
Specifications
- Number of Channels
- 4
- Supply Voltage (Single)
- 3 to 32 V
- Gain Bandwidth Product
- 1.2 MHz
- Slew Rate
- 0.5 V/µs
- Input Offset Voltage (Max)
- 7 mV
- Supply Current (Typ, Four Amplifiers)
- 0.7 mA
- Input Voltage Noise Density
- 35 nV/√Hz
- Operating Temperature
- 0 to 70 °C
- Pins
- 14
- RoHS
- Compliant
Procurement Tips
Specify the exact grade and vendor on the BOM (for example TI LM324BIDR or ST LM324ST) so the assembler cannot substitute a wider-tolerance clone, and ask for the certificate of conformance plus reel photos before dispatch.
Frequently Asked Questions
What is the difference between LM324, LM324A, LM324B and LM2902?
All four share the same pinout and package. The suffix indicates offset grade and temperature range: standard LM324 is 7 mV max offset over 0 °C to 70 °C, LM324A is 3 mV to 4 mV max, and the newer LM324B/LM324BA run to 36 V with 3 mV or 2 mV max offset plus integrated EMI filtering. LM2902 is the same silicon specified from −40 °C to +125 °C for industrial and automotive use.
Is the LM324 rail-to-rail?
No. The input common-mode range reaches the negative rail but stops about 1.5 V below the positive rail, and the output needs roughly 1.5 V of headroom to V+. If you need true rail-to-rail input and output, choose the LMV324, TLV2374 or MCP6004, which are pin-compatible in the 14-pin outline.
Can I use the LM324 as a comparator?
It works for slow, non-critical thresholds, but the LM324 is compensated for linear operation, so open-loop response is slow and the output cannot be pulled up to a different logic rail. For dedicated threshold detection use the LM393 or LM339 dual/quad comparator, which switch in a few hundred nanoseconds and have true open-collector outputs.
Why does my LM324 output not reach 0 V under load?
The class-AB output stage uses a current-source pull-down. With a load to ground the output sits a few millivolts up; TI specifies 5 mV typical and 20 mV maximum at RL of 10 kΩ or less. Pulling the output through a resistor to a negative rail, or adding a small sink resistor to ground, will bring it closer to zero if your application needs it.
How do I spot counterfeit or remarked LM324 parts?
Genuine TI parts carry crisp laser-etched marking that cannot be scraped off, matte-tin leads with a uniform cross-section, and consistent package weight. Compare the date code and lot trace against the manufacturer records, and bench-test a sample for input offset voltage: clones routinely exceed the 7 mV maximum or show mismatched channels.
What is the MOQ and lead time from your Shenzhen warehouse?
MOQ is 1 reel (2,500 pcs) for SOIC-14 tape-and-reel, or 100 pcs loose for prototyping and small-batch production. Local stock ships in 1-2 business days; replenishment through the TI authorized channel takes 5-10 days for standard grades and longer during allocation.
Should I upgrade an existing design to the LM324B?
Usually yes, at no layout cost. The LM324B is a drop-in replacement with 36 V operation, 3 mV max offset, 50 nA max input bias current across −40 °C to +125 °C, 2 kV HBM ESD and integrated RF/EMI rejection — helpful in switching-supply and motor-drive environments where the legacy part picks up rectified RF errors.
Alternatives & Equivalents
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