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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:2,329
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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 only 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 technical context, package-specific pin mapping, real-world use cases, and validated alternative options for low-power analog front-end design.
Technical Context
The LMX321AXK+T employs a bipolar input stage with internal 3.5kΩ series resistors and back-to-back triple diode clamps for ±1.8V differential input protection. Its rail-to-rail output stage uses complementary emitter-follower architecture to achieve 40mV rail margin into 2kΩ at +2.7V.
It is unity-gain stable and drives capacitive loads up to 400pF without external compensation. Input common-mode range extends to VEE − 0.2V (−0.2V at ground-referenced operation), supporting true single-supply sensing below ground reference.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | +2.3V to +7V - enables direct integration with Li-ion, alkaline, or regulated 3.3V/5V rails without level-shifting. |
| Quiescent Current | 105µA per amplifier at +2.7V - supports >1-year battery life in always-on sensor nodes. |
| Gain-Bandwidth Product | 1.3MHz - sufficient for anti-aliasing filters, transimpedance amplifiers, and DC-coupled signal chains up to ~100kHz. |
| Input Offset Voltage | 1–6mV (typ) at +25°C - ensures <0.3% error in 12-bit ADC front-ends with gain ≤10. |
| Output Swing | Within 40mV of rails into 2kΩ - preserves dynamic range in 0–3.3V or 0–5V data acquisition systems. |
| Input Common-Mode Range | VEE − 0.2V to VCC − 0.8V - allows input signals down to −0.2V with single 0V/2.7V supply. |
| Slew Rate | 1V/µs - supports clean 100kHz sine-wave output at 1VP-P without distortion. |
Pinout & Package
LMX321AXK+T is housed in a 5-pin SC70 package (package code X5-1), measuring 2.0mm × 1.25mm × 0.9mm, suitable for ultra-compact PCB layouts in space-constrained portable devices.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | IN+ | Noninverting input - high-impedance node (3MΩ typical) with internal ESD clamp diodes to VCC/VEE. |
| 2 | VEE | Negative supply terminal - connect to ground for single-supply operation; supports split-rail configurations down to −2.5V. |
| 3 | IN− | Inverting input - matched to IN+ for <1µV/°C offset drift; shares same input protection structure. |
| 4 | OUT | Amplifier output - capable of sourcing/sinking ≥10mA (short-circuit tested), drives 2kΩ load to rail ±40mV. |
| 5 | VCC | Positive supply terminal - bypass with 0.1µF ceramic capacitor placed within 2mm of pin for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail output swing | Delivers full-scale output across entire supply range - eliminates need for level-shifting in 3.3V microcontroller interfaces. |
| No phase reversal on overdrive | Prevents latch-up or erroneous output inversion when inputs exceed common-mode limits - critical for fault-tolerant sensor monitoring. |
| Unity-gain stable with 400pF load | Enables direct connection to ADC input capacitors or long PCB traces without isolation resistor - reduces BOM count and layout area. |
| Input common-mode range below ground | Supports true single-supply operation with AC-coupled or bipolar input signals - simplifies front-end design for thermocouple or bridge sensor interfaces. |
| Low input bias current (18–50nA) | Minimizes voltage error across high-impedance sources (e.g., pH electrodes, photodiodes) - maintains accuracy without guard rings or T-networks. |
Applications
| Portable Medical Sensors | Handheld Test Equipment |
|---|---|
Use Scenario: Amplifying low-level bio-potential signals (ECG, EMG) from dry electrodes in battery-powered wearables. IC Role / Device Role / Timing Role: Single-supply instrumentation amplifier front-end with rail-to-rail output driving 12-bit SAR ADC. Use Value: 105µA quiescent current extends battery life beyond 18 months; −0.2V input range accommodates electrode offset without negative rail. |
Use Scenario: Signal conditioning for digital multimeter input stages measuring mV–10V ranges with auto-ranging. IC Role / Device Role / Timing Role: Precision buffer and gain-stage op amp in autoranging attenuator/amp path. Use Value: 1–6mV input offset ensures <0.05% measurement error at 100mV full scale; 1.3MHz GBW supports fast settling during range switching. |
| Low-Power IoT Sensor Nodes | Industrial Battery-Backed Data Loggers |
Use Scenario: Conditioning outputs from MEMS accelerometers and temperature sensors in LoRaWAN edge nodes. IC Role / Device Role / Timing Role: Low-noise, low-drift amplifier feeding MCU's internal ADC under intermittent wake-up duty cycling. Use Value: 66nV/√Hz input noise preserves SNR for sub-mg vibration detection; 105µA ICC enables 10-year shelf life with coin-cell backup. |
Use Scenario: Isolating and scaling 4–20mA loop signals in remote environmental monitors powered by solar-charged LiFePO₄ batteries. IC Role / Device Role / Timing Role: Rail-to-rail I/V converter and output driver interfacing with isolated DAC and microcontroller. Use Value: Output swing to within 40mV of 3.3V rail ensures full utilization of 12-bit DAC resolution; wide supply range (+2.3V to +7V) tolerates battery voltage decay. |
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 150µA ICC, identical 1.3MHz GBW and rail-to-rail output; wider input common-mode range (VEE − 0.1V). | Preferred where lower offset drift (0.5µV/°C vs. 6µV/°C) is required for temperature-stable gain blocks. | Select LMV321IDBVR if system-level thermal drift dominates error budget over quiescent power. |
| TSV911ILT | Lower 80µA ICC, higher 8MHz GBW, but limited input common-mode range (VEE to VCC − 1.2V); no below-ground operation. | Suitable for higher-speed active filters or comparator hysteresis circuits where rail-to-rail input is not needed. | Choose TSV911ILT only when bandwidth >2MHz is mandatory and single-supply input below ground is unnecessary. |
Compared with LMV321IDBVR and TSV911ILT, the LMX321AXK+T uniquely balances ultra-low quiescent current, true below-ground input capability, and proven 400pF capacitive-load drive - making it optimal for energy-constrained, single-supply sensor interfaces where input headroom and power efficiency are co-critical.
Availability
LMX321AXK+T is available at Aetrix Electronics and suitable for portable medical sensors, handheld test equipment, low-power IoT sensor nodes, industrial battery-backed data loggers, and cordless phone audio stages 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, low-power, rail-to-rail signal conditioning in portable and battery-operated systems.
FAQ
What is the maximum capacitive load the LMX321AXK+T can drive without oscillation?
The LMX321AXK+T is unity-gain stable and characterized to drive capacitive loads up to 400pF while maintaining ≥64° phase margin. For loads exceeding 400pF, a series isolation resistor (e.g., 10–100Ω) between the output and capacitor restores stability, as confirmed in Figure 5 of the official datasheet. This behavior is validated across −40°C to +125°C.
Does the LMX321AXK+T support true single-supply operation with input signals below ground?
Yes. The LMX321AXK+T features an input common-mode voltage range extending to VEE − 0.2V. When VEE = 0V (single-supply configuration), inputs can safely operate down to −0.2V - enabling direct interface with transducers that generate negative offsets, such as certain thermocouples or bridge sensors, without external level-shifting circuitry.
What is the typical output voltage swing of the LMX321AXK+T into a 2kΩ load at +2.7V supply?
At +2.7V supply and TA = +25°C, the LMX321AXK+T delivers a typical output swing of VCC − VOH = 40mV and VOL = 40mV into a 2kΩ load - meaning it reaches within 40mV of both rails. This rail-to-rail performance is maintained across the full operating temperature range (−40°C to +125°C), with worst-case swing specified at 130mV.
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 functions (IN+, VEE, IN−, OUT, VCC) match identically, allowing drop-in replacement without PCB modification - provided layout adheres to recommended 0.1µF supply bypassing and input trace shielding.
What is the input protection scheme used in the LMX321AXK+T?
The LMX321AXK+T incorporates internal 3.5kΩ series resistors on both inputs plus back-to-back triple diode clamps across IN+ and IN−. This protects against differential input voltages up to ±1.8V. For |VIN+ − VIN−| > 1.8V, input resistance drops to ~7kΩ and bias current follows IBIAS ≈ (|VDIFF| − 1.8V)/7kΩ - a behavior documented in the "Input Protection Circuit" section of the datasheet.
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:
- -
- 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
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LM358DR
Texas Instruments
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LM2904DR
Texas Instruments
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LM358ADR
Texas Instruments
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LM2904DGKR
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LM324DR
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MCP6006T-E/OT
Microchip Technology
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MCP6006UT-E/OT
Microchip Technology
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LM324PWR
Texas Instruments
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LM2902PWR
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LM2902DR
Texas Instruments
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LM358P
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