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Texas Instruments ADS1251U/2K5G4
- Part No.:
- ADS1251U/2K5G4
- Manufacturer:
- Texas Instruments
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
ADS1251U/2K5G4.pdf
- Description:
- IC ADC 24BIT SIGMA-DELTA 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,765
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Product details
Overview
ADS1251U/2K5G4 from Texas Instruments is a 24-bit delta-sigma analog-to-digital converter (ADC) with no missing codes, 19-bit effective resolution at 20.8kHz data rate, 1.5ppm rms noise, differential inputs, and external reference support (0.5V–5V). It operates from a single +5V supply and targets high-precision measurement in cardiac diagnostics, chromatography, and industrial process control.
For engineers reviewing the ADS1251U/2K5G4 datasheet, ADS1251U/2K5G4 pinout, ADS1251U/2K5G4 application, or ADS1251U/2K5G4 equivalent, key selection criteria include guaranteed 24-bit monotonicity, 20.8kHz maximum data rate with Sinc5 digital filtering, ±15ppm INL, CMOS-compatible serial interface timing, and SO-8 package compatibility with ADS1252 for scalable design.
Technical Context
The ADS1251U/2K5G4 implements a 4th-order delta-sigma modulator with fixed 64× oversampling ratio and a Sinc5 digital filter that delivers notch rejection at integer multiples of the data output rate-enabling precise 50Hz/60Hz power-line interference suppression. Its modulator clock is derived as CLK ÷ 6, yielding 1.333MHz at 8MHz system clock.
It features fully differential switched-capacitor input architecture delivering 98dB common-mode rejection and 80dB PSRR, with input impedance scaling inversely with CLK frequency (e.g., 210kΩ at 8MHz). The device supports synchronous serial communication using DOUT/DRDY dual-function pin and independent SCLK, enabling low-cost isolation via two-wire interface.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 24-bit with guaranteed no missing codes-ensures monotonic transfer function across full range. |
| Data Rate | 20.8kHz max-supports real-time acquisition in high-speed precision instrumentation. |
| Effective Resolution | 19 bits at 20.8kHz (1.5ppm rms noise)-enables sub-1µV detection in 4.096V reference systems. |
| INL | ±15ppm max-limits absolute error to ±0.0015% of full-scale, critical for calibration-grade measurements. |
| Power Consumption | 8mW at 20.8kHz-low quiescent current (1.5–2mA) enables battery-powered portable designs. |
| Reference Range | 0.5V to 5V-allows flexible full-scale adjustment while maintaining fixed internal noise floor. |
| Operating Temp | –40°C to +85°C-qualified for industrial and medical environments without derating. |
Pinout & Package
The ADS1251U/2K5G4 is housed in an SO-8 surface-mount package (Package Code: D), with 1.27mm pitch, 4.9mm × 3.9mm body, and standard JEDEC MS-012AC footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| +VIN | Differential analog input (positive) | Accepts voltage relative to –VIN; bipolar input range = ±VREF when VREF = 4.096V. |
| –VIN | Differential analog input (negative) | Establishes common-mode reference; both inputs must stay within –0.3V to VDD. |
| +VDD | Power supply input | +4.75V to +5.25V single supply; powers analog and digital sections. |
| CLK | System clock input | Schmitt-trigger CMOS input; 8MHz nominal; determines modulator clock (CLK ÷ 6) and data rate. |
| DOUT/DRDY | Serial data output / Data Ready indicator | Open-drain output; pulses LOW to signal valid data; shifts 24-bit Offset Binary Two's Complement MSB-first. |
| SCLK | Serial clock input | Schmitt-trigger CMOS input; controls data read timing; HIGH for ≥20 DRDY cycles enters power-down mode. |
| GND | Analog/digital ground reference | Single ground pin; requires clean analog ground plane connection per layout guidelines. |
| VREF | External reference voltage input | Supplies 32µA typical current; buffered reference recommended to maintain 1.5ppm noise performance. |
Key Features
| Feature | Design Value |
|---|---|
| Delta-sigma architecture with Sinc5 filter | Provides programmable notch rejection at data rate harmonics-enables deterministic 50/60Hz line-noise elimination without analog filters. |
| 24-bit monotonicity guarantee | Ensures no code transitions are skipped across temperature and supply variations-critical for metrology and calibration applications. |
| Differential input with 98dB CMRR | Rejects common-mode noise from thermocouples, bridge sensors, and long cables-reduces need for external instrumentation amplifiers. |
| Flexible reference interface (0.5V–5V) | Permits full-scale optimization: higher VREF improves SNR in ppm terms while preserving absolute noise floor (e.g., 1.5ppm @ 4.096V = 6.14µV rms). |
| Power-down and sync modes via SCLK | Reduces current to <1µA in power-down; enables deterministic multi-converter synchronization with <1 DRDY-cycle skew. |
Applications
| Cardiac Diagnostics | Direct Thermocouple Interfaces |
|---|---|
Use Scenario: High-resolution ECG/EEG signal acquisition with >100dB dynamic range and sub-microvolt sensitivity. IC Role / Device Role / Timing Role: Primary ADC capturing low-amplitude bio-potential signals with 24-bit resolution and 20.8kHz sampling for ST-segment analysis. Use Value: 19-bit effective resolution at 20.8kHz enables detection of 0.5µV-level T-wave anomalies without averaging or decimation. | Use Scenario: Cold-junction-compensated thermocouple measurement in industrial ovens and furnaces. IC Role / Device Role / Timing Role: Direct digitization of µV-level thermocouple outputs with integrated differential input rejecting thermal EMF noise. Use Value: 98dB CMRR and ±15ppm INL eliminate need for external chopper-stabilized amplifiers, reducing BOM cost and board area. |
| Liquid/Gas Chromatography | Precision Process Control |
Use Scenario: Detector signal digitization in HPLC/GC systems requiring stable baseline and <0.01% FSR linearity over 24-hour runs. IC Role / Device Role / Timing Role: High-stability ADC converting photodiode or conductivity detector outputs with minimal drift. Use Value: 0.07ppm/°C offset drift and 0.4ppm/°C gain drift ensure <10ppm total error over 40°C ambient swing-meeting GLP compliance. | Use Scenario: Closed-loop feedback in PLC-based pressure, flow, and level control systems with 4–20mA loop integration. IC Role / Device Role / Timing Role: Isolated front-end ADC interfacing to strain-gauge or RTD sensors via 2-wire synchronous serial link. Use Value: SCLK/DOUT/DRDY isolation-ready interface reduces component count vs SPI-isolated alternatives-cutting isolation barrier cost by 30%. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-resolution delta-sigma ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS1252U/2K5 | 41.7kHz max data rate; identical SO-8 pinout and register map; same 24-bit resolution and 1.5ppm noise. | Higher throughput for faster transient capture; requires higher CLK (16MHz) and increased power (12mW at 41.7kHz). | Select ADS1252U/2K5 only if >20.8kHz sampling is required; otherwise ADS1251U/2K5 offers optimal power/performance trade-off. |
| ADS1253IPW | 4-channel differential input; 20.8kHz per channel; TSSOP-20 package; separate AVDD/DVDD supplies. | Multi-sensor systems (e.g., 4-thermocouple monitoring); higher channel density but larger footprint and layout complexity. | Choose ADS1253IPW for space-constrained multi-channel designs; ADS1251U/2K5 remains optimal for single-channel cost-sensitive applications. |
Compared with ADS1252U/2K5, the ADS1251U/2K5 trades 2× data rate for 40% lower power and simpler clocking; versus ADS1253IPW, it provides identical per-channel performance in half the package size and cost-making it the preferred choice for single-input, low-power precision systems.
Availability
ADS1251U/2K5G4 is available at Aetrix Electronics and suitable for cardiac diagnostics equipment, chromatography detectors, and industrial process controllers requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for ADS1251U/2K5G4 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 data converters and industrial-grade signal chain solutions.
The ADS1251U/2K5G4 belongs to TI's precision delta-sigma ADC family designed for high-dynamic-range measurement in medical, analytical, and industrial instrumentation where 24-bit integrity and low drift are non-negotiable.
FAQ
What is the maximum data rate supported by the ADS1251U/2K5G4?
The ADS1251U/2K5G4 supports a maximum data rate of 20.8kHz when operating with an 8MHz system clock. This rate is fixed by the internal 64× oversampling ratio and Sinc5 filter architecture. Lower rates-from 100Hz down to 16.67Hz-are achievable by reducing the CLK frequency, enabling flexible trade-offs between speed, noise, and power consumption in the ADS1251U/2K5G4 design.
Does the ADS1251U/2K5G4 require an external voltage reference?
Yes, the ADS1251U/2K5G4 requires an external voltage reference connected to the VREF pin. It accepts references from 0.5V to 5V, draws 32µA typical current, and achieves its specified 1.5ppm rms noise only with a low-noise, buffered reference source such as the REF3040 with OPA350 driver-as documented in the ADS1251U/2K5G4 application circuit.
Is the ADS1251U/2K5G4 pin-compatible with other devices in the ADS125x family?
Yes, the ADS1251U/2K5G4 is pin-compatible with the ADS1252U in the SO-8 package, sharing identical pin assignments, register structure, and interface timing. This allows direct substitution for higher-speed applications. However, it is not pin-compatible with the 4-channel ADS1253 or ADS1254, which use TSSOP-20 packages and different pinouts.
What serial interface protocol does the ADS1251U/2K5G4 use?
The ADS1251U/2K5G4 uses a custom 2-wire synchronous serial interface with DOUT/DRDY (dual-function) and SCLK lines. It transmits 24-bit data MSB-first in Offset Binary Two's Complement format, with no chip-select or frame-sync signal required. This minimalist interface simplifies isolation and reduces GPIO usage compared to standard SPI implementations in the ADS1251U/2K5G4 system.
How does the ADS1251U/2K5G4 handle power-line interference rejection?
The ADS1251U/2K5G4 leverages its Sinc5 digital filter to place deep notches at integer multiples of the data output rate. By setting the data rate to 50Hz or 60Hz-via corresponding CLK frequencies (19.2MHz or 23.04MHz)-the device achieves >100dB rejection at those frequencies. For dual 50/60Hz rejection, a 10Hz data rate (CLK = 3.84MHz) places notches at 10Hz, 20Hz, 30Hz, etc., effectively suppressing both standards in the ADS1251U/2K5G4 signal path.
ADS1251U/2K5G4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- Number of Bits:
- 24
- Sampling Rate (Per Second):
- 20k
- Number of Inputs:
- 1
- Input Type:
- Differential
- Data Interface:
- SPI
- Configuration:
- ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- Sigma-Delta
- Reference Type:
- External
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 8-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
ADS1251U/2K5G4 FAQ
1.How can I place an order for ADS1251U/2K5G4 through Aetrix?
Please submit a Request for Quotation (RFQ) for ADS1251U/2K5G4 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 ADS1251U/2K5G4 reliable?
The price and inventory of ADS1251U/2K5G4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADS1251U/2K5G4 is usually 5 days.
3.What payment methods are accepted for ADS1251U/2K5G4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADS1251U/2K5G4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADS1251U/2K5G4?
ADS1251U/2K5G4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADS1251U/2K5G4 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 ADS1251U/2K5G4?
For technical support, including ADS1251U/2K5G4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADS1251U/2K5G4 requirements.
6.How does Aetrix verify that ADS1251U/2K5G4 is sourced from the original manufacturer or authorized distributors?
All ADS1251U/2K5G4 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 ADS1251U/2K5G4 meets industry standards.
7.What is the process for return or replacement of ADS1251U/2K5G4?
All ADS1251U/2K5G4 units undergo pre-shipment inspection (PSI). If there is an issue with ADS1251U/2K5G4, 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 ADS1251U/2K5G4 part is unused and in its original packaging.
Return procedure for ADS1251U/2K5G4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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