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Texas Instruments LM321MFX
- Part No.:
- LM321MFX
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LM321MFX.pdf
- Description:
- IC OPAMP GP 1 CIRCUIT SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,291
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Product details
Overview
LM321MFX 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 including ground, operates from 3 V to 30 V supply, and drives capacitive loads up to 50 pF-ideal for space-constrained single-supply signal conditioning in power supplies and industrial controls.
For engineers reviewing the LM321MFX datasheet, LM321MFX pinout, LM321MFX application, or LM321MFX equivalent, key selection criteria include its wide supply voltage range (3–30 V), low input bias current (45 nA typical), stable operation with high capacitive loads, and compatibility with single-supply systems requiring ground-referenced inputs.
Technical Context
The LM321MFX uses a PNP-input stage enabling true-differential operation with input common-mode voltage extending to −0.3 V below ground and up to V+ − 1.5 V. Its class-A-to-class-B output stage delivers both sourcing (up to 40 mA) and sinking (up to 20 mA) capability while maintaining low quiescent current across supply voltages from 3 V to 30 V.
It achieves 60° phase margin in unity-gain noninverting configuration and maintains ≥65 dB CMRR and PSRR over temperature (−40°C to +85°C). Input offset voltage is 7 mV typical at 25°C, with 9 µV/°C drift over full operating range-suited for precision DC-coupled amplification where thermal stability matters.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain-Bandwidth Product | 1 MHz - sets maximum usable closed-loop bandwidth at unity gain; enables stable AC amplification up to ~100 kHz at gain = 10 |
| Slew Rate | 0.4 V/µs - limits large-signal rise time to ≥2.5 µs for 1-V step; suitable for low-frequency signal conditioning, not high-speed video |
| Supply Current | 430 µA at 5 V - enables battery-powered or energy-sensitive designs; increases only to 660 µA at 30 V due to supply-independent bias network |
| Input Bias Current | 45 nA typical - minimizes voltage error in high-impedance sensor interfaces (e.g., thermistor bridges, photodiode transimpedance) |
| Input Common-Mode Range | −0.3 V to V+ − 1.5 V - allows direct connection of 0-V-referenced sensors (e.g., current-shunt monitors) without level-shifting circuitry |
| Output Swing | 26 V high-side / 20 mV low-side at 30 V supply - delivers near-rail output swing into 2-kΩ load, supporting wide dynamic range in single-supply systems |
| ESD Rating (HBM) | ±300 V - requires standard ESD handling per ANSI/ESDA/JEDEC JS-001; not robust enough for unshielded I/O ports |
Pinout & Package
SOT-23-5 (DBV) package: 2.90 mm × 1.60 mm body, 0.95 mm height, gull-wing leads, RoHS-compliant NiPdAu/Sn lead finish, MSL Level-1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (+IN) | Noninverting Input | High-impedance PNP base node; accepts signals down to −0.3 V; no external clamping needed for normal operation |
| 2 (V−) | Negative Supply | Ground reference in single-supply use; must be connected even when tied to system GND |
| 3 (−IN) | Inverting Input | Differential partner to +IN; used for feedback networks and summing configurations |
| 4 (OUTPUT) | Amplifier Output | Class-A/B push-pull stage; capable of sourcing 40 mA / sinking 20 mA; requires series resistor for direct LED drive |
| 5 (V+) | Positive Supply | Accepts 3–30 V DC; internal bias network ensures stable quiescent current across full range |
Key Features
| Feature | Design Value |
|---|---|
| Single-supply operation with ground-sensing input | Enables direct interfacing to 0-V-referenced sensors (e.g., shunt-based current monitors) without external level shifters or dual supplies |
| Stability with 50-pF capacitive loads | Eliminates need for isolation resistors in many sensor buffer and filter applications, reducing component count and board area |
| Supply-independent quiescent current | Maintains 430–660 µA draw from 5 V to 30 V, simplifying power budgeting in variable-voltage industrial systems |
| Wide operating temperature range | Specified from −40°C to +85°C junction temperature-validated for use in automotive cabin modules and industrial PLC I/O stages |
| Low input offset voltage drift | 9 µV/°C max ensures <100 µV total offset shift across full temperature range-critical for precision DC amplification in instrumentation |
Applications
| Charger Voltage Monitor | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Monitoring battery voltage during constant-current/constant-voltage charging cycles in portable electronics. IC Role / Device Role / Timing Role: Precision DC amplifier in feedback loop of switching charger IC, comparing sensed voltage against reference. Use Value: Ground-referenced input accepts shunt-based voltage divider directly; 7-mV offset ensures ≤0.5% voltage error at 1.4 V reference point. | Use Scenario: Amplifying low-level output from RTD or thermocouple in programmable logic controller analog input module. IC Role / Device Role / Timing Role: First-stage instrumentation amplifier buffer, rejecting common-mode noise on long sensor cables. Use Value: 65 dB CMRR suppresses 60-Hz pickup; 45-nA input bias avoids loading high-impedance thermocouple sources. |
| Desktop Power Supply Feedback | LED Driver Current Regulator |
Use Scenario: Providing voltage feedback to PWM controller in 12-V ATX auxiliary rail regulator. IC Role / Device Role / Timing Role: Error amplifier comparing regulated output against precision reference in isolated flyback topology. Use Value: 1-MHz GBW supports fast transient response; 30-V max supply accommodates auxiliary rail overvoltage conditions. | Use Scenario: Constant-current regulation for indicator LEDs in industrial HMI panels. IC Role / Device Role / Timing Role: Transconductance amplifier converting reference voltage into precise LED current via external sense resistor. Use Value: Output can sink 20 mA directly; 20-mV low-side swing ensures full current control down to 0.2 V across sense resistor. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar single op-amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM321MF/NOPB | Same die, identical electrical specs; differs only in tape-and-reel quantity (1000 vs 3000 units) and marking (A63A vs A63A) | No functional difference; same PCB footprint and thermal profile; suitable for prototype builds or lower-volume production | Select LM321MF/NOPB for evaluation or small-batch assembly where reel size impacts inventory turnover. |
| TLV2461IDBVR | Higher precision: 2.5-mV max VOS, 0.05-µV/°C drift, but higher 550-µA IQ and narrower 2.7–6 V supply range | Better for battery-powered instrumentation; unsuitable for 12–30 V industrial rails where LM321MFX operates reliably | Choose TLV2461IDBVR only when sub-5-mV offset and ultra-low drift outweigh supply flexibility and cost. |
Compared with LM321MF/NOPB, LM321MFX offers identical performance in a larger reel-reducing changeover frequency in high-volume SMT lines-while TLV2461IDBVR trades supply range and cost for precision, making it viable only in low-voltage, high-accuracy roles where LM321MFX's 7-mV offset is insufficient.
Availability
LM321MFX is available at Aetrix Electronics and suitable for industrial sensor interfaces, desktop power supply feedback loops, and LED driver circuits requiring stable component supply across extended temperature ranges and multi-year production cycles.
Supply support for LM321MFX 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and consumer markets.
The LM321 product line delivers economical, robust single op-amps optimized for cost-sensitive, space-constrained applications requiring wide supply range and ground-sensing capability-targeting power management, sensor front-ends, and basic signal conditioning.
FAQ
What is the maximum supply voltage rating for LM321MFX?
The LM321MFX has an absolute maximum supply voltage (V+ − V−) of 32 V, with recommended operating range from 3 V to 30 V. Operation at 30 V is fully characterized across −40°C to +85°C, delivering 26 V high-side output swing into 2-kΩ load. Exceeding 32 V risks permanent damage per Absolute Maximum Ratings.
Does LM321MFX support true single-supply operation with input signals at ground potential?
Yes, LM321MFX supports true single-supply operation: its input common-mode range extends to −0.3 V below ground and up to V+ − 1.5 V. This allows direct connection of 0-V-referenced sources like current-shunt amplifiers or grounded thermistors without level-shifting circuitry-confirmed in Section 7.1 and Table 1 of the SNOS935C datasheet.
Can LM321MFX drive capacitive loads without oscillation?
LM321MFX is specified to remain stable with up to 50 pF capacitive load in worst-case noninverting unity-gain configuration. For larger loads, TI recommends adding resistive isolation (e.g., 10–100 Ω in series with output) or increasing closed-loop gain-details are provided in Section 7.3 and Figure 6 of SNOS935C.
What is the thermal resistance (θJA) of LM321MFX in its SOT-23-5 package?
The LM321MFX in SOT-23-5 (DBV) package has a junction-to-ambient thermal resistance (θJA) of 265°C/W when soldered directly onto a standard PCB, per Section 6.4 of SNOS935C. This value assumes no copper pour or thermal vias; adding 1-in² copper pad reduces θJA significantly-layout guidance is given in Section 10.
Is LM321MFX pin-compatible with other members of the LM321 family?
Yes, LM321MFX shares identical SOT-23-5 (DBV) pinout and electrical characteristics with all LM321 variants including LM321MF/NOPB and LM321MFX/NOPB.B-verified in the Package Option Addendum and Pin Configuration section (Section 5) of SNOS935C. Marking and reel size differ, but PCB layout and firmware require no changes.
LM321MFX 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
LM321MFX FAQ
1.How can I place an order for LM321MFX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM321MFX 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 LM321MFX reliable?
The price and inventory of LM321MFX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM321MFX is usually 5 days.
3.What payment methods are accepted for LM321MFX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM321MFX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM321MFX?
LM321MFX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM321MFX 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 LM321MFX?
For technical support, including LM321MFX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM321MFX requirements.
6.How does Aetrix verify that LM321MFX is sourced from the original manufacturer or authorized distributors?
All LM321MFX 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 LM321MFX meets industry standards.
7.What is the process for return or replacement of LM321MFX?
All LM321MFX units undergo pre-shipment inspection (PSI). If there is an issue with LM321MFX, 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 LM321MFX part is unused and in its original packaging.
Return procedure for LM321MFX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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