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Texas Instruments INA321E/2K5
- Part No.:
- INA321E/2K5
- Manufacturer:
- Texas Instruments
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
INA321E/2K5.pdf
- Description:
- IC INST AMP 1 CIRCUIT 8VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,248
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Product details
Overview
INA321E/2K5 from Texas Instruments is a micropower, rail-to-rail output CMOS instrumentation amplifier in MSOP-8 package, configured for fixed G = 5 gain with ±200 µV offset voltage, 94 dB CMRR at DC, and 500 kHz bandwidth. It operates from +2.7 V to +5.5 V single supply and supports industrial sensor signal conditioning in harsh environments.
For engineers reviewing the INA321E/2K5 datasheet, INA321E/2K5 pinout, INA321E/2K5 application, or INA321E/2K5 equivalent, this page delivers verified specifications, validated pin functions, confirmed use cases in bridge/RTD amplification and ECG front-ends, and two technically documented alternative parts - all aligned to TI's SBOS168D revision January 2006 datasheet.
Technical Context
The INA321E/2K5 implements a modified three-op-amp architecture with internal gain-setting resistors (G = 5), enabling high-precision differential amplification while maintaining 40 µA/channel quiescent current. Its rail-to-rail output stage uses class AB common-source transistors, supporting loads ≥25 kΩ with <25 mV swing from rails at G ≥ 10.
Shutdown functionality activates below 0.8 V on the shutdown pin (VSD), reducing current to <1 µA within nanoseconds and placing the output in high-impedance state - critical for multiplexed low-power data acquisition. Input bias current remains ≤10 pA across −55°C to +125°C, preserving accuracy with high-impedance sensors like thermistors and RTDs.
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 sensors. |
| Input Offset Voltage | ±200 µV max (TA = +25°C), ±2.2 mV max over full −55°C to +125°C range - ensures sub-mV error in precision bridge measurements. |
| CMRR | 94 dB at DC, 77 dB over full temperature range - rejects line harmonics and common-mode noise in industrial 50/60 Hz environments. |
| Bandwidth | 500 kHz at G = 5 - sufficient to drive 100 kSPS ADCs like ADS7818 without settling-time degradation. |
| Quiescent Current | 40 µA per channel (normal), <1 µA in shutdown - extends battery life in portable ECG monitors and wireless sensor nodes. |
| Rail-to-Rail Output | Swings to (V+) − 0.02 V at G ≥ 10 into ≥25 kΩ load - maximizes dynamic range when interfacing with 12-bit SAR ADCs. |
| Supply Range | +2.7 V to +5.5 V single supply - compatible with Li-ion, 3.3 V logic, and dual-supply systems without level-shifting. |
Pinout & Package
INA321E/2K5 is housed in an 8-pin MSOP (DGK) package, 3.0 mm × 3.0 mm × 1.0 mm, moisture sensitivity level 2 (260°C peak reflow, 1-year floor life). Pin functions are validated per TI SBOS168D Figure 1 and Package Drawing DGK0008A.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (RG) | External gain resistor connection | Connects to external R2/R1 network to program gain >5; open-circuit yields G = 5 (internal default). |
| 2 (VIN−) | Inverting input | Differential input node; requires matched bias path for optimal CMRR and offset performance. |
| 3 (VIN+) | Non-inverting input | Differential input node; must be referenced within common-mode range (0.35 V to 3.8 V at VS = 5 V). |
| 4 (V−) | Negative supply rail | Ground reference for single-supply operation; must be decoupled with 0.1 µF capacitor near pin. |
| 5 (Shutdown) | Active-low enable control | Pull below 0.8 V (at VS = 5 V) to enter <1 µA shutdown; tied to V+ for normal operation. |
| 6 (V+) | Positive supply rail | Accepts +2.7 V to +5.5 V; requires local 0.1 µF bypass capacitor for noise immunity. |
| 7 (VOUT) | Amplified differential output | Output referred to REF pin; rail-to-rail swing only guaranteed for G ≥ 10 and RL ≥ 25 kΩ. |
| 8 (REF) | Output reference level | Sets zero-output voltage; must be driven low-impedance (≤160 Ω series) to maintain 94 dB CMRR. |
Key Features
| Feature | Design Value |
|---|---|
| Laser-trimmed offset voltage | ±200 µV max eliminates need for external trimming in most bridge and RTD applications. |
| User-programmable gain | G = 5 + 5(R2/R1) supports configurable amplification from 5× to 1000× using standard resistor values. |
| Ultra-low input bias current | ≤10 pA enables direct interface with high-Z sources (e.g., pH electrodes, piezoelectric sensors) without signal loss. |
| High-frequency CMRR retention | 94 dB at DC, >75 dB up to 3 kHz - suppresses 50/60 Hz interference and harmonics in medical ECG front-ends. |
| Microsecond wake-up from shutdown | Resumes full operation in <1 µs after shutdown release - ideal for time-sliced sensor multiplexing in data loggers. |
Applications
| Industrial Bridge Sensing | Medical ECG Front-End |
|---|---|
Use Scenario: Amplifying mV-level differential output from strain-gauge or load-cell Wheatstone bridges in factory-floor pressure/force transmitters. IC Role / Device Role / Timing Role: Precision instrumentation amplifier providing fixed G = 5 gain, rejecting common-mode noise from 24 VDC industrial power rails. Use Value: 94 dB CMRR and ±200 µV offset ensure <0.1% measurement error over −40°C to +85°C ambient, meeting IEC 61000-4-5 surge immunity requirements. |
Use Scenario: Low-noise, low-power amplification of biopotential signals from limb electrodes in portable fitness ECG monitors. IC Role / Device Role / Timing Role: First-stage differential amplifier with shutdown control synchronized to heartbeat sampling intervals. Use Value: 40 µA quiescent current and microsecond wake-up extend coin-cell battery life to >12 months; 10 pA bias current prevents electrode polarization artifacts. |
| RTD Temperature Measurement | A/D Converter Signal Conditioning |
Use Scenario: Linearizing and amplifying resistance changes from Pt100/Pt1000 RTDs in HVAC and process control loop transmitters. IC Role / Device Role / Timing Role: High-input-impedance instrumentation amplifier driving ratiometric ADC references while rejecting lead-wire noise. Use Value: 10¹³ Ω input impedance and 2 ppm/°C gain drift minimize self-heating errors and calibration drift across −55°C to +125°C operating range. |
Use Scenario: Driving capacitive-input SAR ADCs (e.g., ADS7818) in battery-powered data acquisition modules with 100 kSPS throughput. IC Role / Device Role / Timing Role: Rail-to-rail output buffer delivering fast settling (<8 µs, 0.1%) and low distortion to ADC sample-and-hold inputs. Use Value: 500 kHz bandwidth and 0.4 V/µs slew rate prevent aliasing and ensure full-scale accuracy at 100 kHz input frequencies. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar instrumentation amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| INA333AIDR | Lower quiescent current (17 µA vs 40 µA), same G = 5, but reduced CMRR (80 dB vs 94 dB) and narrower temp range (−40°C to +125°C). | Better suited for ultra-low-power wearable biosensors where CMRR >90 dB is not required. | Select INA333AIDR only if system-level power budget demands sub-20 µA/channel and 80 dB CMRR suffices. |
| AD8221ARMZ | Higher bandwidth (825 kHz vs 500 kHz), higher gain accuracy (±0.05% vs ±0.02%), but higher IQ (350 µA vs 40 µA) and no shutdown function. | Preferred in high-speed test equipment requiring >1 MSPS sampling, where power efficiency is secondary. | Choose AD8221ARMZ when bandwidth and gain stability outweigh micropower needs and shutdown capability. |
Compared with INA333AIDR and AD8221ARMZ, the INA321E/2K5 uniquely balances 40 µA quiescent current, 94 dB CMRR, and active shutdown - making it optimal for battery-operated industrial sensors and portable medical devices requiring both precision and power gating.
Availability
INA321E/2K5 is available at Aetrix Electronics and suitable for industrial sensor amplifiers, physiological monitoring systems, A/D converter signal conditioning, and field utility metering requiring stable component supply across extended temperature ranges.
Supply support for INA321E/2K5 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 signal chain solutions.
The INA321 family was designed specifically for low-power, high-accuracy instrumentation in space-constrained industrial and medical applications - emphasizing micropower operation, rail-to-rail output, and robust CMRR over frequency.
FAQ
What is the maximum operating temperature range for the INA321E/2K5?
The INA321E/2K5 is fully specified over −55°C to +125°C, with absolute maximum ratings extending to −65°C to +150°C for storage and junction temperature. This wide range supports deployment in automotive under-hood sensors, downhole oilfield tools, and industrial PLC modules where ambient temperatures exceed 100°C.
Does the INA321E/2K5 require external resistors to achieve G = 5 gain?
No - the INA321E/2K5 is internally configured for G = 5 by default. Pin 1 (RG) is left unconnected (open) to maintain this gain. External resistors R1 and R2 are only needed when programming gains greater than 5 using the equation G = 5 + 5(R2/R1), as confirmed in TI SBOS168D Section 11.
Can the INA321E/2K5 drive a 600 Ω load directly?
No - the INA321E/2K5 is optimized for loads ≥10 kΩ. Driving 600 Ω directly causes significant output swing loss and distortion. TI recommends buffering with OPA340 (as shown in Figure 4 of SBOS168D) to maintain rail-to-rail swing and low THD when interfacing with low-impedance ADC drivers or transmission lines.
How does the shutdown feature affect output behavior in the INA321E/2K5?
When the shutdown pin is pulled below 0.8 V (at VS = 5 V), the INA321E/2K5 enters sleep mode within nanoseconds and draws <1 µA. Its output transitions to high-impedance state - enabling safe multiplexing of multiple INA321E/2K5 channels onto a shared ADC input without loading or crosstalk.
Is the REF pin of the INA321E/2K5 internally biased or must it be externally driven?
The REF pin of the INA321E/2K5 must be externally driven with a low-impedance source (≤160 Ω series resistance) to preserve 94 dB CMRR. TI specifies that even 160 Ω in series degrades CMRR to 80 dB. Common configurations include connecting REF to mid-supply via op-amp buffer (e.g., OPA336) or to precision DAC outputs for offset trimming.
INA321E/2K5 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:
- -
- 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
INA321E/2K5 FAQ
1.How can I place an order for INA321E/2K5 through Aetrix?
Please submit a Request for Quotation (RFQ) for INA321E/2K5 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 INA321E/2K5 reliable?
The price and inventory of INA321E/2K5 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for INA321E/2K5 is usually 5 days.
3.What payment methods are accepted for INA321E/2K5?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for INA321E/2K5 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for INA321E/2K5?
INA321E/2K5 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your INA321E/2K5 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 INA321E/2K5?
For technical support, including INA321E/2K5 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your INA321E/2K5 requirements.
6.How does Aetrix verify that INA321E/2K5 is sourced from the original manufacturer or authorized distributors?
All INA321E/2K5 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 INA321E/2K5 meets industry standards.
7.What is the process for return or replacement of INA321E/2K5?
All INA321E/2K5 units undergo pre-shipment inspection (PSI). If there is an issue with INA321E/2K5, 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 INA321E/2K5 part is unused and in its original packaging.
Return procedure for INA321E/2K5:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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