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Texas Instruments ADS7811U
- Part No.:
- ADS7811U
- Manufacturer:
- Texas Instruments
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
ADS7811U.pdf
- Description:
- IC ADC 16BIT SAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,307
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Product details
Overview
ADS7811U from Texas Instruments is a 16-bit successive-approximation register (SAR) analog-to-digital converter with integrated sample-and-hold, precision 2.5V reference, and internal clock. It delivers 250kHz throughput, ±2.5V input range, 96dB SFDR at 100kHz, and operates over –25°C to +85°C in industrial systems requiring high-resolution data acquisition.
For engineers reviewing the ADS7811U datasheet, ADS7811U pinout, ADS7811U application, or ADS7811U equivalent, key selection criteria include bipolar input range compatibility, parallel 16-bit two's complement output timing, internal reference stability, and SOIC-28 layout requirements for low-noise signal integrity.
Technical Context
The ADS7811U implements a capacitor-based SAR architecture with inherent sample-and-hold functionality, eliminating external S/H circuitry. Its internal 2.5V reference (±15ppm/°C drift) sets full-scale range, and conversion is controlled via R/C and CS signals with BUSY-driven data latching.
Digital outputs are parallel 16-bit binary two's complement, tri-stated during conversion and enabled only when CS is low and R/C is high. Aperture delay is 40ns, and acquisition time requires ≥4µs between convert pulses to ensure 16-bit accuracy across the ±2.5V input span.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit - supports 76µV LSB step size for ±2.5V full-scale range |
| Throughput Rate | 250kHz - enables real-time sampling of signals up to 1MHz usable bandwidth |
| Input Range | ±2.5V - allows direct interfacing with ±5V-supplied op amps without level-shifting |
| SFDR @ 100kHz | 96dB min - ensures clean spectral analysis in wireless base station receivers |
| Integral Linearity | ±6 LSB - guarantees monotonicity and no missing codes over 15 bits |
| Reference Voltage | 2.5V nominal (2.48–2.52V) - stable internal source eliminates external reference component cost |
| Supply Voltage | +VS = +4.75 to +5.25V, –VS = –5.25 to –4.75V - supports standard dual-rail ±5V systems |
Pinout & Package
The ADS7811U is housed in a 28-pin SOIC (DW) package with three ground pins (pins 2, 5, 14), dual +VS pins (27, 28), and parallel 16-bit data bus (D0–D15).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Analog input | Accepts ±2.5V differential-equivalent signal; high-impedance (100MΩ) after capacitor charge |
| REF (Pin 3) | Reference I/O | Outputs internal 2.5V reference or accepts external 2.3–2.7V source; requires 0.1µF + 2.2µF bypass |
| CAP (Pin 4) | Reference buffer output | Drives internal capacitor array; contains high-frequency switching noise-must not power external circuitry |
| R/C (Pin 24) | Read/Convert control | High = enable data read; low = initiate conversion; timing-critical setup (≥100ns before CS) |
| BUSY (Pin 26) | Conversion status | Falls at conversion start, rises ~3.5µs later; rising edge used to latch D15–D0 into external registers |
| D15–D0 (Pins 6–22) | Parallel data outputs | 16-bit two's complement format; tri-stated when CS high, R/C low, or conversion active |
Key Features
| Feature | Design Value |
|---|---|
| Integrated sample-and-hold | Eliminates need for external S/H circuitry and associated layout complexity |
| On-chip 2.5V reference | Reduces BOM count and improves system-level temperature stability vs. discrete references |
| Parallel 16-bit interface | Enables direct connection to microcontroller or FPGA data buses without serial protocol overhead |
| ±2.5V bipolar input range | Supports direct digitization of AC-coupled sensor signals and instrumentation amplifier outputs |
| SOIC-28 industrial package | Facilitates manual assembly and rework while meeting –25°C to +85°C operating requirements |
Applications
| Wireless Base Stations | Spectrum Analysis |
|---|---|
Use Scenario: Digitizing IF signals in multi-carrier GSM/CDMA receiver front-ends. IC Role / Device Role / Timing Role: High-linearity ADC capturing 100kHz–1MHz band-limited signals with minimal harmonic distortion. Use Value: 96dB SFDR ensures adjacent-channel interference remains below –96dBc, preserving signal fidelity in dense RF environments. | Use Scenario: Real-time FFT-based frequency domain monitoring in lab-grade spectrum analyzers. IC Role / Device Role / Timing Role: Precision digitizer feeding FPGA-based FFT engines with deterministic 4µs conversion cycle. Use Value: ±6 LSB integral linearity prevents spectral leakage and maintains amplitude accuracy across full 16-bit code range. |
| Imaging Systems | Data Acquisition |
Use Scenario: Converting analog outputs from CCD or CMOS image sensor timing controllers. IC Role / Device Role / Timing Role: Bipolar-input ADC handling reset-level and pixel-level voltage offsets in scientific imaging pipelines. Use Value: ±10mV bipolar zero error and <0.8 LSB transition noise preserve low-contrast detail in calibrated grayscale images. | Use Scenario: High-accuracy voltage logging in automated test equipment and environmental monitoring nodes. IC Role / Device Role / Timing Role: Standalone data converter interfaced to microcontroller via parallel bus for burst-mode sampling. Use Value: Internal reference and 250kHz throughput enable consistent 16-bit measurements without external calibration or clock distribution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-resolution SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS8325IPW | 16-bit, 100kSPS, SPI interface, external reference required | Lacks integrated reference and parallel bus; suited for lower-speed, space-constrained designs | Select when board area is critical and system already provides precision external reference |
| AD7606BSTZ | 16-bit, 200kSPS, simultaneous sampling, ±10V input range | Requires external ±15V supplies and external reference; targets multi-channel industrial DAQ | Choose for 8-channel synchronized acquisition where ±10V range and isolation exceed ADS7811U capability |
Compared with ADS7811U, ADS8325IPW trades throughput and integration for serial interface compactness, while AD7606BSTZ adds channel count and input range at the cost of higher supply complexity and no internal reference-making ADS7811U optimal for single-channel, ±5V-powered, reference-integrated precision systems.
Availability
ADS7811U is available at Aetrix Electronics and suitable for wireless infrastructure, spectral monitoring, scientific imaging, and industrial data acquisition requiring stable component supply and long-term manufacturability.
Supply support for ADS7811U 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, embedded processing, and digital signal technologies with decades of precision data converter innovation.
The ADS7811U belongs to TI's precision SAR ADC product line, engineered for high-fidelity signal capture in demanding instrumentation, communications, and test equipment applications.
FAQ
What is the maximum recommended acquisition time between conversions for ADS7811U?
The ADS7811U requires ≥4µs between falling edges of the convert pulse to guarantee full acquisition of the ±2.5V input signal onto its internal sampling capacitor. This interval ensures the sample-and-hold settles to within 1 LSB (76µV) before conversion begins, maintaining specified 16-bit linearity and SNR performance across temperature.
Can ADS7811U operate with an external reference, and what is the acceptable voltage range?
Yes, ADS7811U can accept an external reference applied to the REF pin within 2.3V to 2.7V. When using an external source, the internal 2.5V reference is bypassed. However, full electrical specifications-including SFDR, SINAD, and linearity-are guaranteed only with the internal reference; external reference use may degrade performance due to gain/offset errors.
How does the BUSY signal function in ADS7811U timing, and why is its rising edge critical?
The BUSY signal in ADS7811U falls at conversion start and rises ~3.5µs later, indicating data validity on D15–D0. Its rising edge serves as a hardware latch trigger-used in typical implementations (e.g., with 74HC574) to capture the 16-bit result synchronously. Delaying latching beyond t11 (25–35ns after BUSY rise) risks reading invalid or metastable states.
What is the purpose of the CAP pin on ADS7811U, and how must it be decoupled?
The CAP pin on ADS7811U is the output of the internal reference buffer, directly connected to the SAR capacitor array. It carries high-frequency switching transients during bit decisions and must never power external circuitry. It requires strict decoupling: a 0.1µF ceramic capacitor placed immediately adjacent to the pin, plus a 2.2µF tantalum in parallel, both referenced to analog ground.
Does ADS7811U support true bipolar input operation, and how is zero-scale error managed?
Yes, ADS7811U supports true bipolar input operation with a ±2.5V range centered at 0V. Its bipolar zero error is specified as ±10mV, meaning the actual code transition from FFFFh (–76µV) to 0000h (0V) occurs within that offset window. This error drifts only ±2ppm/°C, ensuring stable midscale alignment across the –25°C to +85°C industrial temperature range.
ADS7811U Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 250k
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- Parallel
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- ±5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -25°C ~ 85°C
- Supplier Device Package:
- 28-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
ADS7811U FAQ
1.How can I place an order for ADS7811U through Aetrix?
Please submit a Request for Quotation (RFQ) for ADS7811U 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 ADS7811U reliable?
The price and inventory of ADS7811U are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ADS7811U is usually 5 days.
3.What payment methods are accepted for ADS7811U?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ADS7811U transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ADS7811U?
ADS7811U orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ADS7811U 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 ADS7811U?
For technical support, including ADS7811U datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ADS7811U requirements.
6.How does Aetrix verify that ADS7811U is sourced from the original manufacturer or authorized distributors?
All ADS7811U 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 ADS7811U meets industry standards.
7.What is the process for return or replacement of ADS7811U?
All ADS7811U units undergo pre-shipment inspection (PSI). If there is an issue with ADS7811U, 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 ADS7811U part is unused and in its original packaging.
Return procedure for ADS7811U:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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