The LM324ADT from STMicroelectronics is a quad low-power operational amplifier in a 14-pin SOIC package. It contains four independent high-gain internally compensated op-amps designed for single-supply operation from 3 V to 30 V (or dual supplies \u00b11.5 V to \u00b115 V). Key specs include 1.3-MHz gain bandwidth product, 0.4-V\/\u00b5s slew rate, 2-mV typical input offset voltage, 20-nA input bias current, 100-dB voltage gain, and 70-dB minimum CMRR. The output voltage swings from near ground to VCC-1.5V. Quiescent current is 1.2 mA max for all four amplifiers at 5 V. Operating temperature range is 0\u00b0C to +70\u00b0C. The ‘A’ suffix denotes improved grade with lower offset voltage (3 mV max vs 7 mV for standard).<\/p>","protected":false},"excerpt":{"rendered":"
The LM324ADT from STMicroelectronics is a quad low-power operational amplifier in a 14-pin SOIC package. It contains four independent high-gain internally compensated op-amps designed for single-supply operation from 3 V to 30 V (or dual supplies \u00b11.5 V to \u00b115 V). Key specs include 1.3-MHz gain bandwidth product, 0.4-V\/\u00b5s slew rate, 2-mV typical input offset […]<\/p>\n","protected":false},"author":2,"featured_media":2880,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19,13],"tags":[],"chip_brand":[142],"class_list":["post-2048","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-analog-linear-ics","category-integrated-circuits-ics","chip_brand-st"],"acf":{"brief_explanation":"Quad op-amp, 3-30V single supply, 1.3MHz GBW, 2mV Vos, 100dB gain, SOIC-14, 0~70\u00b0C, improved A-grade","date_code":"","package_case":"SOIC-14 (8.65 x 3.9 x 1.65 mm, 1.27mm pitch)","in_stock":175000,"datasheet":"https:\/\/www.st.com\/resource\/en\/datasheet\/lm324.pdf","price":"$0.09 (2.5K+ pcs)","product_introduction":"The LM324ADT from STMicroelectronics is the improved 'A' grade of the industry-standard LM324 quad operational amplifier. The 'A' grade offers tighter input offset voltage (3 mV max vs 7 mV for standard grade), making it suitable for applications requiring better DC precision without paying for premium op-amps. The device is pin-compatible with all LM324\/LM224\/LM2902 variants across manufacturers.\n\nThe LM324 family is one of the most widely used op-amp ICs in the world, valued for its single-supply operation, low cost, and quad-channel integration. All four amplifiers share a common VCC and GND, with each amplifier having independent inputs and outputs. The input common-mode voltage range includes ground (0 V), enabling direct sensing of signals near the negative rail without level shifting \u2014 a key advantage over dual-supply op-amps.\n\nThe output voltage swings from approximately 5 mV above ground (under light load) to VCC - 1.5 V, providing a usable output range in single-supply applications. The 40-mA typical output current at VCC = 15 V can directly drive LEDs, relays, and low-impedance loads without additional transistors.\n\nThe SOIC-14 package provides a compact surface-mount footprint (8.65 x 3.9 mm) for modern PCB designs. The 'DT' suffix in the ST part number denotes SOIC-14 tape-and-reel packaging. The low 1.2-mA total quiescent current (all four amplifiers) at 5 V makes the LM324ADT suitable for battery-operated equipment.\n\nTypical applications include transducer amplifiers, DC gain blocks, active filters, comparators, oscillators, and general-purpose signal conditioning in consumer, industrial, and automotive systems. The LM324ADT is not recommended for new designs requiring high precision or high speed; consider TI's LM324B (3 mV max Vos, EMI filtering, 36-V supply) for upgrades.","working_principle":"**Bipolar Input Stage:** Each of the four amplifiers in the LM324 uses a PNP differential input pair with a current-mirror active load. The PNP inputs enable the common-mode range to extend below ground by approximately -0.3 V, a critical feature for single-supply operation. The input bias current (20 nA typical) flows out of the input pins (PNP base current), which must be considered when designing high-impedance input networks.\n\n**Gain and Compensation:** The high 100-dB open-loop gain is achieved through two voltage-gain stages. Internal dominant-pole compensation (typically 5-10 pF) sets the unity-gain bandwidth to 1.3 MHz and ensures stability in unity-gain voltage-follower configurations without external capacitors.\n\n**Class-AB Output Stage:** The output stage uses a class-AB push-pull configuration that can both source and sink current. However, the sink current capability (typically 12-50 \u00b5A at low VOUT) is much weaker than the source capability, resulting in asymmetrical output drive. This is why the LM324 output cannot truly swing to ground under load \u2014 a pull-down resistor is needed for low-voltage outputs.\n\n**Single-Supply Architecture:** The internal bias network is designed to operate from a single positive supply with no negative supply required. The ground pin (VCC-) serves as the reference for all internal bias currents and the output stage. This eliminates the need for a negative supply rail, reducing system complexity and cost.","pin_description":"
| Pin<\/th> | Name<\/th> | Type<\/th> | Description<\/th><\/tr><\/thead> | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1<\/td> | 1OUT<\/td> | O<\/td> | Amplifier 1 output; swings 5mV to VCC-1.5V; \u00b140mA source\/sink capability<\/td><\/tr> | ||||||||||||||||||||||||||||
| 2<\/td> | 1IN-<\/td> | I<\/td> | Amplifier 1 inverting input; 20nA bias current flows out of pin<\/td><\/tr> | ||||||||||||||||||||||||||||
| 3<\/td> | 1IN+<\/td> | I<\/td> | Amplifier 1 non-inverting input; common-mode range includes ground<\/td><\/tr> | ||||||||||||||||||||||||||||
| 4<\/td> | VCC+<\/td> | P<\/td> | Positive supply; 3V to 30V; bypass with 0.1\u00b5F ceramic<\/td><\/tr> | ||||||||||||||||||||||||||||
| 5<\/td> | 2IN+<\/td> | I<\/td> | Amplifier 2 non-inverting input<\/td><\/tr> | ||||||||||||||||||||||||||||
| 6<\/td> | 2IN-<\/td> | I<\/td> | Amplifier 2 inverting input<\/td><\/tr> | ||||||||||||||||||||||||||||
| 7<\/td> | 2OUT<\/td> | O<\/td> | Amplifier 2 output<\/td><\/tr> | ||||||||||||||||||||||||||||
| 8<\/td> | 3OUT<\/td> | O<\/td> | Amplifier 3 output<\/td><\/tr> | ||||||||||||||||||||||||||||
| 9<\/td> | 3IN-<\/td> | I<\/td> | Amplifier 3 inverting input<\/td><\/tr> | ||||||||||||||||||||||||||||
| 10<\/td> | 3IN+<\/td> | I<\/td> | Amplifier 3 non-inverting input<\/td><\/tr> | ||||||||||||||||||||||||||||
| 11<\/td> | GND\/VCC-<\/td> | G<\/td> | Ground \/ negative supply; connect to ground for single-supply operation<\/td><\/tr> | ||||||||||||||||||||||||||||
| 12<\/td> | 4IN+<\/td> | I<\/td> | Amplifier 4 non-inverting input<\/td><\/tr> | ||||||||||||||||||||||||||||
| 13<\/td> | 4IN-<\/td> | I<\/td> | Amplifier 4 inverting input<\/td><\/tr> | ||||||||||||||||||||||||||||
| 14<\/td> | 4OUT<\/td> | O<\/td> | Amplifier 4 output<\/td><\/tr><\/tbody><\/table>","application_scenarios":"
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