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Analog Devices Inc./Maxim Integrated LMX321AXK-T
- Part No.:
- LMX321AXK-T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 5-TSSOP, SC-70-5, SOT-353
- Datasheet:
-
LMX321AXK-T.pdf
- Description:
- IC OPAMP GP 1 CIRCUIT SC70-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,116
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Product details
Overview
LMX321AXK-T from Maxim Integrated is a single-channel, rail-to-rail output operational amplifier optimized for low-voltage, battery-powered systems. It operates from +2.3V to +7V, draws 105µA quiescent current per amplifier at +2.7V, delivers 1.3MHz gain-bandwidth product, and swings within 40mV of both supply rails into 2kΩ loads - enabling precision signal conditioning in portable medical sensors and handheld instrumentation.
For engineers reviewing the LMX321AXK-T datasheet, LMX321AXK-T pinout, LMX321AXK-T application, or LMX321AXK-T equivalent, this page provides verified electrical parameters, SC70-5 package layout, rail-to-rail output behavior under load, input common-mode range extending below ground (VEE − 0.2V), and validated alternatives for low-power op amp selection.
Technical Context
The LMX321AXK-T uses bipolar process technology and features an input stage with internal 3.5kΩ series resistors plus back-to-back triple diode stacks for differential input protection. Its rail-to-rail output stage employs complementary emitter-follower architecture to achieve 40mV swing margin into 2kΩ at VCC = +2.7V.
It is unity-gain stable and supports capacitive loads up to 400pF without external compensation. The device exhibits no phase reversal on overdriven inputs and eliminates crossover distortion, making it suitable for single-supply transducer interfaces and active filter stages requiring clean small-signal fidelity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | +2.3V to +7V - enables direct operation from single Li-ion cell (3.0–4.2V) or two alkaline cells (3.0V nominal). |
| Quiescent Current | 105µA per amplifier at +2.7V - supports >1-year battery life in always-on sensor nodes drawing <10µA average system current. |
| Gain-Bandwidth Product | 1.3MHz - sufficient for anti-aliasing filters up to ~100kHz and closed-loop gain ≥10 with phase margin >64°. |
| Input Common-Mode Range | VEE − 0.2V to VCC − 0.8V - allows sensing signals referenced below ground (e.g., thermocouple cold-junction compensation). |
| Output Voltage Swing | Within 40mV of either rail into 2kΩ - preserves full dynamic range in 3.3V ADC front-ends with 0–3.3V input span. |
| Input Offset Voltage | 1–6mV (typical, +25°C) - supports DC-coupled amplification of mV-level transducer outputs without trimming. |
| Slew Rate | 1V/µs - adequate for 100kHz sine waves at 10Vpp without slew-induced distortion. |
Pinout & Package
LMX321AXK-T is housed in a 5-pin SC70-5 package (package code X5-1), measuring 2.0mm × 1.25mm × 0.9mm, with 0.65mm lead pitch and moisture sensitivity level 1 (MSL1). This ultra-small outline supports high-density PCB layouts in space-constrained wearables and IoT edge nodes.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | IN+ | Noninverting input - accepts differential or single-ended signals; input bias current ≤50nA ensures minimal error in high-impedance sensor bridges. |
| 2 | VEE | Negative supply terminal - tied to ground in single-supply configurations; enables true ground-referenced input common-mode range. |
| 3 | IN− | Inverting input - used for feedback networks and differential amplification; protected by internal 3.5kΩ series resistors and diode clamps. |
| 4 | OUT | Amplifier output - drives 2kΩ loads to within 40mV of rails; capable of sourcing/sinking ≥10mA short-circuit current. |
| 5 | VCC | Positive supply terminal - requires local 0.1µF ceramic bypass capacitor to minimize PSRR degradation above 10kHz. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail output swing | Delivers full-scale output into 2kΩ loads across entire supply range (+2.3V to +7V), maximizing ADC utilization in low-voltage data acquisition. |
| No phase reversal on overdrive | Prevents latch-up or erroneous control signals when input exceeds common-mode limits - critical for fault-tolerant industrial I/O modules. |
| Input common-mode range below ground | Extends to VEE − 0.2V, supporting direct interfacing with bipolar sensors (e.g., strain gauges, RTDs) without level-shifting circuitry. |
| Unity-gain stability with 400pF load | Eliminates need for external isolation resistors in capacitive sensor interfaces (e.g., piezoelectric pickups, touch panels) up to 400pF. |
| Low 105µA quiescent current | Enables continuous monitoring mode in battery-powered devices with multi-year operational lifetime at µA-level system sleep currents. |
Applications
| Portable Medical Sensors | Handheld Test Equipment |
|---|---|
Use Scenario: Amplifying microvolt-level ECG electrode signals in compact wearable monitors with single 3.0V coin-cell supply. IC Role / Device Role / Timing Role: Single-supply transducer interface amplifier providing DC-coupled gain, rail-to-rail output swing, and input range extending below ground for differential biopotential measurement. Use Value: Eliminates level-shifting components and reduces BOM count by 3 parts while maintaining 80dB CMRR at 60Hz with VCM = −0.1V to +1.7V. |
Use Scenario: Buffering analog outputs in pocket-sized multimeters where PCB area is constrained to <15mm² per channel. IC Role / Device Role / Timing Role: Low-quiescent-current voltage follower driving 10kΩ DMM input impedance with <1mV offset error across temperature. Use Value: Achieves ±0.1% accuracy over −40°C to +125°C using only 105µA supply current - reducing thermal drift and self-heating errors. |
| Active Filter Stages | Low-Power Industrial I/O |
Use Scenario: Implementing 2nd-order Sallen-Key low-pass filter (fc = 10kHz) in battery-operated environmental sensor nodes. IC Role / Device Role / Timing Role: Unity-gain stable op amp configured as buffer and integrator with 1.3MHz GBW supporting phase margin >64° at fc. Use Value: Maintains filter Q-factor and cutoff accuracy without external compensation, even with 330pF ceramic filter capacitors and PCB stray capacitance. |
Use Scenario: Conditioning 4–20mA loop receiver signals in explosion-proof field transmitters powered by 24V loop with strict 3.5mA max draw. IC Role / Device Role / Timing Role: Precision current-to-voltage converter with input bias current ≤50nA and PSRR >82dB to reject loop noise. Use Value: Enables 16-bit resolution over full temperature range using only 105µA per amplifier - leaving >3mA headroom for MCU and RF subsystem. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar general-purpose op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMV321IDBVR | Higher quiescent current (130µA), wider input common-mode range (VEE to VCC − 0.1V), same SC70-5 package. | Better for higher-speed applications (1.5MHz GBW) but less optimal for sub-100µA battery budgets. | Select LMV321IDBVR if needing marginally faster settling or improved PSRR (90dB vs. 82dB) at cost of +25µA supply current. |
| TSV611ICT | Lower quiescent current (65µA), lower GBW (160kHz), rail-to-rail input/output, same SC70-5 footprint. | Optimized for ultra-low-power sensor signal chains where bandwidth <200kHz suffices. | Choose TSV611ICT when extending battery life is paramount and 1.3MHz bandwidth is unnecessary - saves ~40µA per amplifier. |
Compared with LMX321AXK-T, LMV321IDBVR trades 25µA higher supply current for +200kHz GBW and enhanced PSRR, while TSV611ICT reduces current by 40µA but sacrifices >85% bandwidth - making LMX321AXK-T the balanced choice for 100kHz–1MHz, sub-120µA portable signal conditioning.
Availability
LMX321AXK-T is available at Aetrix Electronics and suitable for portable medical sensors, handheld test equipment, active filter stages, and low-power industrial I/O requiring stable component supply across extended temperature ranges (−40°C to +125°C).
Supply support for LMX321AXK-T 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
Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for demanding industrial, automotive, and communications applications.
The LMX321AXK-T belongs to Maxim's LMX321/LMX358/LMX324 family - engineered specifically for low-voltage, rail-to-rail output operation in battery-powered and space-constrained systems where quiescent current, package size, and input/output voltage range are critical.
FAQ
What is the operating temperature range of the LMX321AXK-T?
The LMX321AXK-T is rated for continuous operation from −40°C to +125°C. Electrical specifications including input offset voltage (9mV max), supply current (210µA max), and output swing (90mV max VOL into 2kΩ) are guaranteed across this full industrial temperature range, making it suitable for under-hood automotive sensors and outdoor industrial controllers.
Does the LMX321AXK-T require external compensation for unity-gain stability?
No, the LMX321AXK-T is internally compensated for unity-gain stability and remains stable driving capacitive loads up to 400pF. Test data confirms phase margin >64° with CL = 200pF and RL = 2kΩ, eliminating the need for external isolation resistors in most sensor and filter applications - unlike many low-power op amps requiring ≥10Ω series output resistance.
What is the input common-mode voltage range for the LMX321AXK-T at +5V supply?
At VCC = +5V and VEE = 0V, the LMX321AXK-T supports an input common-mode voltage range of −0.2V to +4.2V (typical, for CMRR >72dB). This extends 0.2V below ground, enabling direct connection to bipolar transducers like thermocouples or bridge circuits without level-shifting components - a key advantage over standard rail-to-rail input op amps.
Can the LMX321AXK-T drive a 10kΩ load to within 10mV of the supply rails?
No - the LMX321AXK-T drives 2kΩ loads to within 40mV of the rails (VCC − VOH ≤ 40mV, VOL ≤ 40mV at +2.7V). Into 10kΩ, typical swing improves to ≤20mV (VCC − VOH ≤ 20mV, VOL ≤ 20mV at +2.7V), but not 10mV. For sub-10mV rail margins, consider higher-output-drive op amps such as MAX4475 or ADA4077.
Is the LMX321AXK-T pin-compatible with the LMV321 family?
Yes - the LMX321AXK-T is explicitly designed as a pin-to-pin compatible upgrade to the LMV321 family in SC70-5 and SOT23-5 packages. Pin 1 (IN+), Pin 2 (VEE), Pin 3 (IN−), Pin 4 (OUT), and Pin 5 (VCC) match identically, allowing drop-in replacement without PCB modification while delivering lower quiescent current (105µA vs. 130µA) and improved input range.
LMX321AXK-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 5-TSSOP, SC-70-5, SOT-353
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 1
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 1V/µs
- Gain Bandwidth Product:
- 1.3 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 18 nA
- Voltage - Input Offset:
- 1 mV
- Current - Supply:
- 120µA
- Current - Output / Channel:
- 28 mA
- Voltage - Supply Span (Min):
- 2.3 V
- Voltage - Supply Span (Max):
- 7 V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SC-70-5
LMX321AXK-T FAQ
1.How can I place an order for LMX321AXK-T through Aetrix?
Please submit a Request for Quotation (RFQ) for LMX321AXK-T 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 LMX321AXK-T reliable?
The price and inventory of LMX321AXK-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMX321AXK-T is usually 5 days.
3.What payment methods are accepted for LMX321AXK-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMX321AXK-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMX321AXK-T?
LMX321AXK-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMX321AXK-T 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 LMX321AXK-T?
For technical support, including LMX321AXK-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMX321AXK-T requirements.
6.How does Aetrix verify that LMX321AXK-T is sourced from the original manufacturer or authorized distributors?
All LMX321AXK-T 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 LMX321AXK-T meets industry standards.
7.What is the process for return or replacement of LMX321AXK-T?
All LMX321AXK-T units undergo pre-shipment inspection (PSI). If there is an issue with LMX321AXK-T, 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 LMX321AXK-T part is unused and in its original packaging.
Return procedure for LMX321AXK-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LMX321AXK-T Tags
-
LM358DT
STMicroelectronics
-
LM358DR
Texas Instruments
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LM2904DR
Texas Instruments
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LM358ADR
Texas Instruments
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LM2904DGKR
Texas Instruments
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LM324DR
Texas Instruments
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MCP6006T-E/OT
Microchip Technology
-
MCP6006UT-E/OT
Microchip Technology
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LM324PWR
Texas Instruments
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LM2902PWR
Texas Instruments
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LM2902DR
Texas Instruments
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LM358P
Texas Instruments
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