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Texas Instruments LM321MF
- Part No.:
- LM321MF
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM321MF.pdf
- Description:
- IC OPAMP GP 1 CIRCUIT SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,500
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Product details
Overview
LM321MF from Texas Instruments is a low-power single operational amplifier in SOT-23-5 package, featuring 1 MHz gain-bandwidth product, 0.4 V/µs slew rate, and 430 µA quiescent current at 5 V. It supports rail-to-rail input common-mode range down to ground and operates from 3 V to 30 V supply, enabling use in single-supply industrial sensor signal conditioning and power supply feedback loops.
For engineers reviewing the LM321MF datasheet, LM321MF pinout, LM321MF application, or LM321MF equivalent, key selection criteria include its wide supply voltage range (3–30 V), low input bias current (45 nA), stable operation with capacitive loads up to 50 pF, and compatibility with single-supply systems requiring ground-referenced inputs.
Technical Context
The LM321MF uses a PNP-input stage enabling true-differential inputs and input common-mode voltage down to −0.3 V (at 25°C), allowing direct ground-referenced operation. Its class-A-to-class-B output stage delivers 40 mA sourcing and 20 mA sinking capability while maintaining low quiescent current across supply voltages from 3 V to 30 V.
Internal biasing ensures supply current independence over the full operating voltage range, and phase margin remains at 60° in unity-gain non-inverting configuration - critical for stability when driving moderate capacitive loads without external compensation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain-Bandwidth Product | 1 MHz - sets maximum closed-loop bandwidth at unity gain; usable for DC-coupled signal conditioning up to ~100 kHz at gain = 10. |
| Slew Rate | 0.4 V/µs - limits large-signal response time; supports ≤100 kHz full-power sine wave at 1 Vpp output swing. |
| Supply Current | 430 µA at 5 V - enables battery-powered or energy-sensitive applications with minimal standby drain. |
| Input Bias Current | 45 nA - permits high-impedance sensor interfacing (e.g., thermistors, photodiodes) without significant offset error. |
| Input Common-Mode Range | −0.3 V to (V+ − 1.5 V) - allows direct connection of 0-V-referenced sensors in single-supply systems. |
| Output Short-Circuit Current | 40 mA - defines safe drive capability into low-impedance loads or fault conditions without latch-up. |
| Operating Temperature | −40°C to +85°C - qualified for industrial ambient environments including power supplies and motor controls. |
Pinout & Package
SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 1.0 mm height, gull-wing leads, RoHS-compliant NiPdAu/Sn finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| +IN (Pin 1) | Noninverting Input | High-impedance node accepting ground-referenced or positive input signals; bias current flows out of pin. |
| V− (Pin 2) | Negative Supply | Connect to ground in single-supply operation; required reference for internal bias network and output stage. |
| −IN (Pin 3) | Inverting Input | High-impedance feedback node; used in standard inverting amplifier, summing, or transimpedance configurations. |
| OUTPUT (Pin 4) | Amplifier Output | Class-AB stage capable of sourcing 40 mA / sinking 20 mA; requires external pull-down for defined state during power-down. |
| V+ (Pin 5) | Positive Supply | Accepts 3–30 V DC; powers all internal circuitry; bypass capacitor (0.1 µF ceramic) must be placed adjacent to this pin. |
Key Features
| Feature | Design Value |
|---|---|
| Single-supply operation with ground-sensing input | Enables direct interface to 0-V-referenced sensors (e.g., bridge transducers, thermocouples) without level-shifting circuitry. |
| Stable with 50-pF capacitive load | Eliminates need for isolation resistor in many sensor buffer and filter driver applications, reducing component count and board space. |
| Supply current independent of V+ | Maintains consistent 430 µA draw from 3 V to 30 V, simplifying power budgeting across variable-input power supplies. |
| Robust ESD protection | HBM rating of ±300 V reduces risk of handling damage during assembly, supporting reliable manufacturing in standard ESD-safe environments. |
| Wide temperature range support | Specified performance from −40°C to +85°C ensures stable gain, offset, and CMRR in industrial control cabinets and outdoor power electronics. |
Applications
| Charger Feedback Control | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Regulating constant-current/constant-voltage output in AC/DC wall adapters and USB PD chargers. IC Role / Device Role / Timing Role: Error amplifier comparing sensed output voltage/current against reference in feedback loop of switching controller. Use Value: Low 430 µA supply current minimizes auxiliary power loss; rail-to-rail input enables accurate sensing near ground or VOUT. | Use Scenario: Amplifying mV-level outputs from RTDs, strain gauges, or pressure transducers in PLC analog input modules. IC Role / Device Role / Timing Role: Precision DC-coupled gain stage with low input bias current to avoid loading high-impedance bridges. Use Value: 45 nA input bias current prevents measurement error in 100-kΩ+ sensor networks; −0.3 V to V+−1.5 V input range accommodates unipolar sensor excitation. |
| LED/Lamp Driver | Power Supply Monitoring |
Use Scenario: Constant-current LED driver in indicator panels or backlight dimming circuits using PWM modulation. IC Role / Device Role / Timing Role: Transconductance amplifier converting PWM duty cycle into proportional LED current via external pass transistor. Use Value: 40 mA sourcing capability drives base of NPN/PNP boost transistors; stable output stage avoids oscillation under PWM transient loading. | Use Scenario: Overvoltage/undervoltage detection and brown-out monitoring in 12 V/24 V industrial power rails. IC Role / Device Role / Timing Role: Comparator replacement in window detector or threshold comparator circuits with hysteresis. Use Value: Input common-mode range includes ground and VCC, enabling direct sensing of rail voltage without resistive dividers; 1 MHz GBW supports fast fault response. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar single op-amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM321MFX/NOPB | Same electrical specs and SOT-23-5 package; differs only in tape-and-reel quantity (3000 vs. 1000 units). | No functional difference; identical use cases including sensor buffering and power feedback. | Select LM321MFX/NOPB for high-volume production runs requiring larger reels to reduce changeover frequency. |
| TLV2461IDBVR | Higher precision: 2.5 mV max VOS, 1.2 V/µs slew rate, but higher 600 µA supply current and narrower 2.7–6 V supply range. | Better suited for precision instrumentation where offset and speed matter more than supply voltage flexibility. | Choose TLV2461IDBVR only when sub-mV offset and faster settling are required; LM321MF remains optimal for cost-sensitive 3–30 V industrial designs. |
Compared with LM321MFX/NOPB, the LM321MF offers identical performance in a smaller reel format ideal for prototyping and low-volume builds; versus TLV2461IDBVR, the LM321MF trades precision for wider supply range and lower quiescent current - making it more suitable for general-purpose industrial power and sensor interfaces.
Availability
LM321MF is available at Aetrix Electronics and suitable for industrial sensor interfaces, power supply feedback loops, and LED driver circuits requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM321MF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and digital signal technologies, with decades of experience in precision amplifiers and power management ICs.
The LM321MF belongs to TI's legacy low-power op-amp family designed for cost-effective, robust signal conditioning in industrial, consumer, and computing power systems where wide supply range and ground-sensing capability are essential.
FAQ
What is the maximum supply voltage rating for the LM321MF?
The LM321MF has an absolute maximum supply voltage rating of 32 V between V+ and V− pins, with recommended operating range specified from 3 V to 30 V. Operation at 32 V is permissible only under short-duration transient conditions; continuous operation above 30 V risks exceeding thermal limits and degrading long-term reliability. The LM321MF maintains stable performance across this full range due to supply-independent biasing.
Does the LM321MF support true single-supply operation with input signals referenced to ground?
Yes, the LM321MF supports true single-supply operation: its input common-mode voltage range extends to −0.3 V (at 25°C) and up to V+ − 1.5 V, allowing direct connection of ground-referenced sensors or signals. This eliminates the need for level-shifting circuitry in applications like RTD amplification or battery-monitoring comparators, and is confirmed by TI's Electrical Characteristics table and Figure 7 in the SNOS935C datasheet.
Can the LM321MF drive capacitive loads without oscillation?
The LM321MF is characterized for stable operation with up to 50 pF capacitive load in worst-case non-inverting unity-gain configuration, per TI's datasheet Section 7.3 and Typical Characteristics. For larger loads, external series resistance (e.g., 10–100 Ω) between amplifier output and capacitance restores phase margin. This capability makes the LM321MF suitable for driving ADC input filters or long PCB traces without added compensation components.
What is the output current capability of the LM321MF?
The LM321MF provides 40 mA sourcing current and 20 mA sinking current under typical conditions (V+ = 15 V, TA = 25°C), as specified in the Electrical Characteristics table. At elevated temperatures (−40°C to +85°C), minimum sinking current drops to 5 mA and sourcing to 10 mA. These values define safe drive capability into LEDs, small relays, or transistor bases - exceeding standard rail-to-rail op-amps while retaining low quiescent current.
Is the LM321MF pin-compatible with other members of the LM321 family?
Yes, the LM321MF shares identical SOT-23-5 (DBV) pinout and electrical behavior with all LM321 variants including LM321MFX/NOPB, LM321MF/NOPB, and LM321MF/NOPB.B - confirmed by TI's Package Option Addendum and Pin Configuration section. Differences are limited to reel size (1000 vs. 3000 units), date code, and packaging markings (A63A); no functional or layout changes exist between these orderable part numbers.
LM321MF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 0.4V/µs
- Gain Bandwidth Product:
- 1 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 45 nA
- Voltage - Input Offset:
- 2 mV
- Current - Supply:
- 660µA
- Current - Output / Channel:
- 40 mA
- Voltage - Supply Span (Min):
- 3 V
- Voltage - Supply Span (Max):
- 30 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LM321MF FAQ
1.How can I place an order for LM321MF through Aetrix?
Please submit a Request for Quotation (RFQ) for LM321MF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM321MF reliable?
The price and inventory of LM321MF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM321MF is usually 5 days.
3.What payment methods are accepted for LM321MF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM321MF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM321MF?
LM321MF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM321MF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM321MF?
For technical support, including LM321MF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM321MF requirements.
6.How does Aetrix verify that LM321MF is sourced from the original manufacturer or authorized distributors?
All LM321MF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM321MF meets industry standards.
7.What is the process for return or replacement of LM321MF?
All LM321MF units undergo pre-shipment inspection (PSI). If there is an issue with LM321MF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM321MF part is unused and in its original packaging.
Return procedure for LM321MF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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