LM321 Single Operational Amplifier

LM321 Single Operational Amplifier
LM321 Single Operational Amplifier
LM321 Pinout
LM321 Single Operational Amplifier
LM321 Pinout

click on image to enlarge

The LM321 is a low power single Operational Amplifier with a high unity gain frequency and a specified 0.4-V/µs slew rate, the quiescent current is only 430-µA/amplifier (at 5V). The LM321 is available in SOT-23 packages.


LM321 IC Pinout Configuration

Pin Number

Pin Name



Non- Inverting Input (IN+)

The Non-Inverting Pin of the Op-Amp



Connected to negative rail or ground


Inverting Input (IN-)

The Inverting pin of the Op-Amp



Output pin of the Op-Amp



Connected to the positive rail of supply voltage 


LM321 features and specifications

  • Supply Voltage: 3V to 32V
  • SR - Slew Rate: 0.4 V/us
  • Output Current per Channel: 40 mA
  • Vos - Input Offset Voltage: 0.3 mV
  • Operating Supply Current: 10 mA
  • CMRR - Common Mode Rejection Ratio: 85 dB
  • Gain V/V: 100 V/mV
  • PSRR - Power Supply Rejection Ratio: 100 dB
  • Available in the SOT-23 package


Note: Complete Technical Details can be found in the LM321 datasheet given at the end of this page.


Equivalent for LM321:  UA741, CA3140, TL081, MC33171, OP07

Alternatives Amplifiers: LM4871, AD620, IC6283, JRC45558, LF351


Where to use LM321 Op Amp IC

The LM321 single operational amplifier offers a wide input voltage range of 3V to 32V minimum combined with a high CMRR of 85 dB and high input impedance to provide high accuracy in the noninverting circuit configuration. LM321 can maintain excellent linearity and gain accuracy even at high closed-loop gains. The LM321 has excellent Stability of offsets and gain with time or variations in temperature. These features made the LM321 an industry standard for instrumentation applications.


So if you looking for an Op-Amp with wide input voltage range and higher stability and accuracy with temperature variations, then this IC might be the right choice for you.


How to Use LM321 Op Amp IC

Power amplifier application circuit from LM321 Datasheet is shown below. Resistor R1 and R2 are used to set the voltage gain. In this circuit LM321, the op-amp is used to amplify the current of a BJT transistor. The output of the amplifier is connected to the base of BJT which amplifies the current. Current gain is set by β, the current gain of a BJT. The resulting output provides high power to the load. Differential voltage supplies are necessary.

LM321 Application Circuit

Applications of LM321 IC

  • Wireless base station control circuits
  • Optical network control circuits
  • Instrumentation
  • Sensors and controls
  1. Thermocouples
  2. Resistor thermal detectors (RTDs)
  3. Strain bridges
  4. Shunt current measurements
  • Precision filters


2D-Model of LM321

Dimensions of the LM321 SOT-23 package are given below.

LM321 Op-Amp Dimensions



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