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Texas Instruments INA321EA/250
- Part No.:
- INA321EA/250
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
INA321EA/250.pdf
- Description:
- IC INST AMP 1 CIRCUIT 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,018
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Product details
Overview
INA321EA/250 from Texas Instruments is a rail-to-rail output, micropower CMOS instrumentation amplifier in MSOP-8 package, configured for fixed 5V/V gain with external resistor programmability (G = 5 + 5·R₂/R₁), ±200 µV offset voltage, 94 dB CMRR at DC, and 500 kHz bandwidth - deployed in precision bridge sensor signal conditioning for industrial metering.
For engineers reviewing the INA321EA/250 datasheet, INA321EA/250 pinout, INA321EA/250 application, or INA321EA/250 equivalent, key selection criteria include micropower operation (40 µA/channel), shutdown current <1 µA, rail-to-rail output swing within 20 mV of rails, −55°C to +125°C temperature range, and CMOS input bias current (10 pA) enabling high-impedance sensor interfacing.
Technical Context
The INA321EA/250 implements a three-op-amp instrumentation architecture with internal gain-setting resistors for G = 5, extended via external R₁/R₂ to 5–1000 V/V. Its CMOS input stage delivers 10 pA bias current and 10¹³ Ω || 3 pF input impedance, while the Class AB output stage supports rail-to-rail swing under ≥10 kΩ loads.
Shutdown control operates at <0.8 V (5 V supply), reducing quiescent current to <1 µA with microsecond wake-up; common-mode rejection remains ≥77 dB up to 3 kHz, and PSRR exceeds 90 dB across 10 Hz–100 kHz - critical for rejecting line harmonics in single-supply industrial sensor front-ends.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain Accuracy | ±0.02% at G = 5, 2 ppm/°C drift - enables stable gain over temperature without recalibration in field-deployed meters. |
| Input Offset Voltage | ±200 µV max (25°C), ±2.2 mV over −55°C to +125°C - ensures sub-0.1% error in 10 mV full-scale bridge outputs. |
| CMRR | 94 dB at DC, ≥77 dB up to 3 kHz - rejects 50/60 Hz noise and harmonics in ECG and utility metering applications. |
| Bandwidth | 500 kHz at G = 5 - supports fast settling (<12 µs to 0.01%) for multiplexed multi-channel data acquisition. |
| Quiescent Current | 40 µA per channel, <1 µA in shutdown - extends battery life in portable physiological monitors and wireless sensors. |
| Supply Range | +2.7 V to +5.5 V - compatible with Li-ion, 3.3 V logic, and dual-supply systems without level-shifting. |
| Output Swing | (V+) − 0.02 V, (V−) + 0.02 V at RL ≥ 25 kΩ - preserves dynamic range when driving SAR ADCs like ADS7818 directly. |
Pinout & Package
INA321EA/250 is housed in an MSOP-8 (DGK) package, 3.0 mm × 3.0 mm × 1.0 mm, moisture sensitivity level 2, RoHS-compliant, with exposed thermal pad (not electrically connected).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RG) | External Gain Resistor Terminal | Connects to R₁/R₂ network to set gain >5 V/V; open-circuit yields G = 5; high-impedance node requiring low-parasitic layout. |
| 2 (VIN−) | Inverting Input | Differential input terminal; requires matched bias-current return path (e.g., equal resistors to REF or ground) to prevent saturation. |
| 3 (VIN+) | Non-inverting Input | Differential input terminal; shares same high-impedance, low-bias-current characteristics as VIN− for balanced sensor interfaces. |
| 4 (V−) | Negative Supply Rail | Ground reference for single-supply operation or negative rail in bipolar systems; must be decoupled with 0.1 µF capacitor. |
| 5 (Shutdown) | Active-Low Enable Control | Pull <0.8 V (5 V supply) to enter <1 µA shutdown; rising edge wakes device in microseconds - ideal for time-division multiplexing. |
| 6 (V+) | Positive Supply Rail | +2.7 V to +5.5 V input; requires local 0.1 µF ceramic decoupling adjacent to pin to suppress supply noise coupling into REF or inputs. |
| 7 (VOUT) | Amplified Output | Rail-to-rail output referenced to REF pin; drives capacitive loads ≤50 pF directly; heavier loads require OPA340 buffering per Figure 4. |
| 8 (REF) | Output Reference Level | Defines zero-output voltage; must be low-impedance (≤160 Ω series) to maintain 94 dB CMRR; used for offset trimming or level-shifting. |
Key Features
| Feature | Design Value |
|---|---|
| Micropower Shutdown | Draws <1 µA during sleep mode with microsecond wake-up - enables energy harvesting and battery-powered sensor nodes. |
| User-Programmable Gain | G = 5 + 5·(R₂/R₁) supports precise gain scaling from 5 to 1000 V/V using standard 0.1% resistors, minimizing external component count. |
| Rail-to-Rail Output Stage | Swings within 20 mV of V+ and V− under light loads - maximizes ADC utilization in 3.3 V or 5 V systems without level-shifting circuitry. |
| High CMRR Over Frequency | Maintains ≥77 dB CMRR up to 3 kHz - rejects power-line interference in medical ECG and industrial RTD measurement without additional filtering. |
| Laser-Trimmed Precision | ±200 µV offset and ±0.02% gain error at 25°C - eliminates need for system-level calibration in cost-sensitive industrial transmitters. |
Applications
| Industrial Bridge Sensor Amplifier | Physiological Signal Acquisition |
|---|---|
Use Scenario: Amplifying mV-level differential output from strain-gauge load cells or Wheatstone bridges in smart utility meters and factory floor pressure transmitters. IC Role / Device Role / Timing Role: Primary signal-conditioning stage converting bridge imbalance to clean, amplified, single-ended output for 12-bit SAR ADC sampling at ≤100 kHz. Use Value: 40 µA quiescent current enables always-on monitoring in battery-backed meters; 94 dB CMRR suppresses 50/60 Hz pickup from nearby AC wiring. | Use Scenario: Front-end amplification of low-amplitude, high-impedance biopotentials (ECG, EMG) in portable fitness trackers and clinical diagnostic devices. IC Role / Device Role / Timing Role: First-stage instrumentation amplifier providing high common-mode rejection and ultra-low input bias current to avoid electrode polarization errors. Use Value: 10 pA input bias current prevents signal distortion from dry electrodes; shutdown mode reduces average power to <1 µA between heartbeat intervals. |
| A/D Converter Driver | Differential Line Receiver with Gain |
Use Scenario: Directly driving capacitive-input SAR ADCs (e.g., ADS7818) in low-power data loggers and IoT edge nodes. IC Role / Device Role / Timing Role: Output buffer and gain stage ensuring fast settling (<12 µs to 0.01%) and minimal charge kickback into ADC sample capacitor. Use Value: Rail-to-rail swing and 500 kHz bandwidth enable full-scale utilization of 12-bit ADCs at sampling rates up to 100 kSPS without external op-amp buffering. | Use Scenario: Receiving and amplifying differential analog signals over noisy PCB traces or short cables in PCMCIA cards and communication interface modules. IC Role / Device Role / Timing Role: Differential receiver with programmable gain, rejecting ground bounce and crosstalk while preserving signal integrity in mixed-signal subsystems. Use Value: 10¹³ Ω input impedance prevents loading of high-Z sources; 500 kHz bandwidth supports baseband audio and telemetry signal conditioning up to 100 kHz. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA3221EA/250 | Same MSOP-8 package, identical pinout, but includes integrated 2-wire I²C digital interface and internal 12-bit ADC - adds digital functionality at cost of higher quiescent current (75 µA). | Replaces analog-only signal chains with digital output capability; unsuitable where only analog output is required or board space is constrained by extra I²C routing. | Select INA3221EA/250 only if digital output, on-chip ADC, or I²C-configurable gain is needed; otherwise INA321EA/250 offers lower power and simpler analog interface. |
| AD8221ARMZ-REEL | SOIC-8 package, 0.3 µV/°C offset drift vs INA321EA/250's ±7 µV/°C, but higher 1.2 mA quiescent current and no shutdown mode. | Better long-term stability for high-precision lab equipment; incompatible with battery-powered or multiplexed systems due to lack of shutdown and higher power. | Choose AD8221ARMZ-REEL for metrology-grade accuracy where power is not constrained; INA321EA/250 preferred for portable, low-power, or time-multiplexed designs. |
Compared with INA3221EA/250 and AD8221ARMZ-REEL, the INA321EA/250 uniquely balances micropower operation (40 µA), true shutdown (<1 µA), and precision (±200 µV offset) in a minimal 3×3 mm footprint - making it optimal for space- and energy-constrained industrial and medical sensor nodes where pure analog output suffices.
Availability
INA321EA/250 is available at Aetrix Electronics and suitable for industrial sensor amplifiers, physiological signal acquisition, and A/D converter signal conditioning requiring stable component supply across automotive, medical, and energy metering programs.
Supply support for INA321EA/250 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 and embedded processing technologies, with decades of expertise in precision amplifiers and sensor interface ICs.
The INA321 family was designed specifically for low-power, high-accuracy instrumentation in harsh environments - targeting industrial process control, medical diagnostics, and utility infrastructure where wide temperature range (−55°C to +125°C) and micropower operation are mandatory.
FAQ
What is the maximum gain achievable with INA321EA/250 using external resistors?
The INA321EA/250 supports externally programmable gain from 5 V/V to 1000 V/V using the equation G = 5 + 5·(R₂/R₁). At G = 1000, R₂/R₁ = 199; practical implementation requires precision-matched resistors with low temperature coefficients to maintain gain accuracy and minimize drift. The datasheet confirms this range applies across the full −55°C to +125°C operating temperature.
Does INA321EA/250 require external decoupling capacitors, and where should they be placed?
Yes, INA321EA/250 requires 0.1 µF ceramic decoupling capacitors placed as close as possible to both V+ (Pin 6) and V− (Pin 4) pins. This placement minimizes supply impedance at high frequencies and prevents noise coupling into the REF and input terminals - critical for maintaining 94 dB CMRR and preventing oscillation in high-gain configurations.
Can INA321EA/250 drive a 600 Ω load directly, or is buffering required?
The INA321EA/250 is optimized for loads ≥10 kΩ; driving a 600 Ω load directly causes significant output swing degradation and increased distortion. TI's Application Note SBOS168D explicitly recommends buffering with OPA340 (MSOP-8) for such low-impedance loads - the OPA340 provides rail-to-rail swing and can source/sink ±25 mA, preserving signal fidelity when driving ADC reference buffers or transmission lines.
How does the REF pin affect input common-mode range in INA321EA/250?
The REF pin directly sets the output zero level and influences the lower bound of the input common-mode range via VOA1 = 5/4·VCM − 1/4·VREF. For example, with VREF = 1.25 V and VCM = 0.55 V (at VS = 5 V), the input common-mode range extends down to ~0.35 V. Maintaining low-impedance connection to REF (≤160 Ω) is essential to preserve 94 dB CMRR - higher series resistance degrades rejection to 80 dB.
Is INA321EA/250 suitable for use with thermistor or RTD sensors in industrial temperature measurement?
Yes, INA321EA/250 is explicitly listed in TI's Applications section for RTD and thermistor interfaces. Its 10 pA input bias current prevents self-heating errors in high-resistance thermistors (>10 kΩ), while ±200 µV offset and 94 dB CMRR ensure accurate extraction of small resistance changes - especially when paired with constant-current excitation and ratiometric ADC conversion to cancel reference drift.
INA321EA/250 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Amplifier Type:
- Instrumentation
- Number of Circuits:
- 1
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 0.4V/µs
- Gain Bandwidth Product:
- -
- -3db Bandwidth:
- 500 kHz
- Current - Input Bias:
- 0.5 pA
- Voltage - Input Offset:
- 200 µV
- Current - Supply:
- 40µA
- Current - Output / Channel:
- 16 mA
- Voltage - Supply Span (Min):
- 2.5 V
- Voltage - Supply Span (Max):
- 5.5 V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-VSSOP
INA321EA/250 FAQ
1.How can I place an order for INA321EA/250 through Aetrix?
Please submit a Request for Quotation (RFQ) for INA321EA/250 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 INA321EA/250 reliable?
The price and inventory of INA321EA/250 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA321EA/250 is usually 5 days.
3.What payment methods are accepted for INA321EA/250?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA321EA/250 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA321EA/250?
INA321EA/250 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA321EA/250 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 INA321EA/250?
For technical support, including INA321EA/250 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA321EA/250 requirements.
6.How does Aetrix verify that INA321EA/250 is sourced from the original manufacturer or authorized distributors?
All INA321EA/250 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 INA321EA/250 meets industry standards.
7.What is the process for return or replacement of INA321EA/250?
All INA321EA/250 units undergo pre-shipment inspection (PSI). If there is an issue with INA321EA/250, 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 INA321EA/250 part is unused and in its original packaging.
Return procedure for INA321EA/250:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
INA321EA/250 Tags
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