ADS7811U/1KG4 - 16-Bit 250kHz SAR ADC, 28-SOIC | TI
MPN: ADS7811U/1KG4 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $18.5 | $18.50 |
| 10 | $16.2 | $162.00 |
| 100 | $13.95 | $1,395.00 |
| 500 | $11.4 | $5,700.00 |
| 1,000 | $9.85 | $9,850.00 |
ADS7811U/1KG4 Overview
A SAR ADC is a type of analog-to-digital converter that uses a binary-search successive-approximation algorithm to digitize an input signal one code at a time per clock cycle. SAR ADCs sit in the data-converter hierarchy between flash converters (which are fastest but lowest resolution) and delta-sigma converters (which offer the highest resolution at lower bandwidth). The SAR architecture is favored for 12- to 18-bit, 100-kSPS-to-1-MSPS multi-channel data-acquisition systems where low latency, deterministic throughput, and excellent AC linearity are required.
Key features of the ADS7811U/1KG4 include 250 kHz throughput, integral nonlinearity typically 0.0092%, ±10 V (or 0 to 4 V) true bipolar input ranges, a serial data interface, and an operating temperature range of -25 °C to +85 °C. The internal 2.5 V reference is trimmed for low drift, and a REF_OUT pin supplies external circuitry. The 28-pin SOIC footprint occupies a modest board area suited to industrial data-acquisition boards, instrumentation front-ends, and DSP-ready signal chains.
Typical applications include industrial process-control analog input modules, multi-channel data-acquisition systems, digital signal processing front-ends, test and measurement equipment, and medical instrumentation signal chains where 16-bit resolution at moderate sample rates is required. The wide bipolar input range supports direct connection to ±10 V transducer outputs without external signal conditioning.
When designing with this device, ensure the analog and digital supplies are decoupled with 10 µF tantalum and 0.1 µF ceramic capacitors placed as close as possible to the supply pins. Maintain a clean analog ground plane separate from the digital ground, joining them only at the AGND-to-DGND pin. The conversion clock, serial data, and CS signals should be routed away from the analog input traces to avoid digital noise coupling into the conversion result.
This page synthesizes distributor pricing, drop-in compatible alternatives, and practical design notes that go beyond the manufacturer datasheet.
Drop-in alternatives for ADS7811U/1KG4 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ADS7811U/1KG4 (same form factor and footprint) — differing in Operating Temperature Range, Package, Architecture, Number of Input Channels, Resolution.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
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ADS7811U/1KE4
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ADS7811U/1KG4 Maximum Ratings & Electrical Characteristics
| Resolution | 16 bits |
| Sample Rate (max) | 250 kHz |
| Architecture | SAR (Successive Approximation Register) |
| Number of Input Channels | 1 (single-ended) |
| Analog Supply Voltage | ±5 V (bipolar) or +5 V (single supply) |
| Digital Supply Voltage | +5 V |
| Analog Input Voltage Range | 0 V to +2.5 V (single-ended) |
| Integral Nonlinearity (INL) | ±2 LSB (max), 0.0092% typical |
| Signal-to-Noise Ratio (SNR) | 85 dB (typical) |
| Spurious-Free Dynamic Range (SFDR) | >100 dB at 100 kHz input |
| Differential Nonlinearity (DNL) | No missing codes (16-bit) |
| Input Type | Single-ended, bipolar or unipolar |
| Data Interface | Serial (synchronous, SPI-compatible) |
| Internal Reference | Yes, 2.5 V |
| Operating Temperature Range | -25 °C to +85 °C |
| Package | 28-SOIC (DW) 7.5 mm body width |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Lead-Free / Halogen-Free | Yes / Yes |
ADS7811U/1KG4 Pin Configuration
| Pin 1 | AIN — Analog input |
| Pin 2 | RANGE — Input range select |
| Pin 3 | MODE — Mode select |
| Pin 4 | BYTE — Byte select |
| Pin 5 | DGND — Digital ground |
| Pin 6 | DB15 — Data bit 15 (MSB, parallel mode) |
| Pin 7 | DB14 — Data bit 14 |
| Pin 8 | DB13 — Data bit 13 |
| Pin 9 | DB12 — Data bit 12 |
| Pin 10 | DB11 — Data bit 11 |
| Pin 11 | DB10 — Data bit 10 |
| Pin 12 | DB9 — Data bit 9 |
| Pin 13 | DB8 — Data bit 8 |
| Pin 14 | DB7 — Data bit 7 |
| Pin 15 | DB6 — Data bit 6 |
| Pin 16 | DB5 — Data bit 5 |
| Pin 17 | DB4 — Data bit 4 |
| Pin 18 | DB3 — Data bit 3 |
| Pin 19 | DB2 — Data bit 2 |
| Pin 20 | DB1 — Data bit 1 |
| Pin 21 | DB0 — Data bit 0 (LSB, parallel mode) |
| Pin 22 | CS — Chip select (active low) |
| Pin 23 | BUSY — Conversion in progress output |
| Pin 24 | DOUT — Serial data output |
| Pin 25 | SCLK — Serial clock input |
| Pin 26 | VANA — Analog supply (+/-5 V or +5 V) |
| Pin 27 | VDD — Digital supply (+5 V) |
| Pin 28 | REF_OUT — Internal 2.5 V reference output |
Typical Applications
ADS7811U/1KG4 is suitable for 7 applications: Industrial Process Control Analog Input Module, Multi-Channel Data Acquisition Systems, Digital Signal Processing Front-End, Test and Measurement Instrumentation, Medical Instrumentation Signal Chains, Audio Signal Analysis and Processing, Motor Control Feedback and Sensor Conditioning.
Industrial Process Control Analog Input Module
The ADS7811U/1KG4 is well-suited for industrial process-control analog input modules that digitize ±10 V transducer signals from pressure, flow, and temperature sensors. Its 16-bit resolution (96 dB dynamic range) yields 0.3 mV LSB on a ±10 V input, providing more than sufficient resolution for loop-powered 4-20 mA derived voltage measurements. The internal 2.5 V reference removes a precision external reference from the BOM and eliminates reference drift as a calibration term. At 250 kSPS, a single channel can be multiplexed to sample 8-16 channels at 30 kSPS per channel, matching typical industrial control update rates. The 28-SOIC footprint is rugged for industrial -25 °C to +85 °C environments and supports hand-solderable rework, unlike tiny QFN alternatives.
Recommended
Multi-Channel Data Acquisition Systems
Multi-channel data-acquisition systems using an analog multiplexer (MUX) can use the ADS7811U/1KG4 as the digitizer for many input channels. At 250 kSPS, the device can sample eight channels at 31 kSPS per channel, or sixteen channels at 15 kSPS per channel - well within typical PC-based DAQ card budgets. The 16-bit, no-missing-codes performance preserves full dynamic range across the multiplexed channel switching. The SAR architecture produces a deterministic, low-latency result per conversion - critical for time-stamped DAQ records that need sample-accurate timing. The serial SPI-compatible interface minimizes board-routing complexity versus parallel-output converters.
Recommended
Digital Signal Processing Front-End
The ADS7811U/1KG4 serves as a low-latency front end for DSP-based signal-processing boards where deterministic sample timing is critical. SAR ADCs deliver one conversion per clock cycle with zero pipeline latency, unlike pipeline or delta-sigma converters that introduce multi-cycle or filter-induced delays. For control loops (motor control, power-factor correction, audio effects), this low latency and deterministic timing allow a DSP to react within a single sample interval. The 85 dB SNR and >100 dB SFDR support audio-band DSP algorithms such as FFT-based spectrum analysis, while the serial interface consumes only a few DSP serial-port pins, leaving other peripherals free.
Recommended
Test and Measurement Instrumentation
Bench-top and rack-mounted test and measurement equipment - including digital multimeter front-ends, source-measure units, and bench oscilloscopes' reference-digitizer channels - can use the ADS7811U/1KG4 for its 16-bit, 250 kSPS performance. The internal 2.5 V reference is trimmed for low drift, supporting 0.01%-of-reading accuracy after calibration. The bipolar ±10 V input range allows direct connection to ±10 V standard instrumentation outputs without an external instrumentation amplifier. SFDR >100 dB at 100 kHz input means clean spectrum analysis for bench measurement of low-level AC signals without converter-induced spurs.
Recommended
Medical Instrumentation Signal Chains
Medical instrumentation signal chains, including patient monitors, ECG/EKG digitizers, blood-pressure measurement boards, and electro-surgical generator calibration boards, can use the ADS7811U/1KG4 as the 16-bit, 250 kSPS digitizer. The converter's excellent 100 dB SFDR provides headroom for digitizing physiological signals in the presence of high-amplitude interferers such as RF ablation energy. The internal low-drift reference stabilizes measurement gain over time without per-board trimming. The 28-SOIC footprint remains workable for medical device prototypes that may migrate to larger-volume QFN packages later. Always confirm compliance to IEC 60601-1 system-level safety requirements at the final assembly level.
Recommended
Audio Signal Analysis and Processing
Audio-band analysis tools, acoustic measurement microphones, professional audio analyzers, and broadcast equipment sample-rate converters can use the ADS7811U/1KG4 to digitize signals up to the 250 kHz Nyquist boundary. The 85 dB SNR and >100 dB SFDR translate to clean spectrum analysis results for FFT-based acoustic measurement tools. The serial interface simplifies connectivity to common audio DSPs (SHARC, Blackfin) and to microcontrollers that handle audio streaming. The internal 2.5 V reference removes gain drift as a concern over temperature, supporting lab-grade audio measurement calibration. For consumer audio, a smaller pin-compatible ADC such as ADS1110 is usually preferable; the ADS7811U/1KG4 shines in professional audio measurement.
Recommended
Motor Control Feedback and Sensor Conditioning
Servo-motor drives, industrial inverter controllers, and BLDC motor control boards can use the ADS7811U/1KG4 to digitize phase-current sensing signals, DC-bus voltage monitors, and resolver-derived position signals. The SAR ADC's deterministic latency (one conversion per clock, no pipeline delay) closes the loop sample-by-sample, which simplifies discrete-time current-mode control algorithms. The ±10 V bipolar input range allows direct connection to current-sense amplifier outputs centered on a common-mode voltage. At 250 kSPS, the part samples motor-phase currents at 10 kHz to 50 kHz PWM switching frequencies, providing enough oversampling for harmonic-ripple current reconstruction. Integrate RC anti-aliasing filters at the analog-input pin per TI's SAR-ADC front-end guidelines.
Recommended
Recommended Products Summary
Engineering reference data for ADS7811U/1KG4 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | ADS7811U | ADS7811U/1KE4 | ADS7811 |
|---|---|---|---|---|
| Package | 28-SOIC (DW) | 28-SOIC (DW) - same | 28-SOIC (DW) - same | 28-SOIC (DW) - same |
| Brand | Texas Instruments | Texas Instruments - same | Texas Instruments - same | Texas Instruments - same |
| Resolution | 16 bits | 16 bits | 16 bits | 16 bits |
| Sample Rate | 250 kSPS | 250 kSPS | 250 kSPS | 250 kSPS |
| Architecture | SAR | SAR | SAR | SAR |
| Internal Reference | 2.5 V integrated | 2.5 V integrated | 2.5 V integrated | 2.5 V integrated |
| Input Range | Bipolar ±10 V (differential) / 0-2.5 V | Bipolar ±10 V / 0-2.5 V | Bipolar ±10 V / 0-2.5 V | Bipolar ±10 V / 0-2.5 V |
| Operating Temperature | -25 °C to +85 °C | -25 °C to +85 °C | -25 °C to +85 °C | -25 °C to +85 °C |
| Packaging Carrier | 1,000-piece T&R reel | Tube | Cut-tape reel | Tube or bulk |
| RoHS Compliance | Yes (Pb-free, RoHS Green) | Yes | Yes | Yes |
Key Differentiators
- Internal 2.5 V reference eliminates external reference BOM cost (vs ADS7807U (external reference required))
- 16-bit, no-missing-codes performance (vs ADS7808UB (12-bit))
- Bipolar ±10 V input range for direct industrial transducer connection (vs ADS7813UB (0-5 V single supply))
Design Notes
Decouple the VANA (±5 V analog) and VDD (+5 V digital) supplies with a 10 µF tantalum bulk capacitor plus a 0.1 µF ceramic capacitor placed as close to the IC pins as possible. Estimated: at 250 kSPS with full-scale ±10 V input, supply current spikes during the SAR successive-approximation switching event, so the local 0.1 µF must provide the high-frequency charge. Keep the analog and digital ground planes separate and join them only at the AGND-to-DGND pin to avoid digital return currents polluting the analog reference.
Route the analog-input trace as a short, guarded trace on the top layer with a continuous ground plane underneath. The SAR ADC draws a transient charge from the input each conversion cycle (estimated 2-5 pC), so the analog source impedance should be below 1 kΩ to settle within the acquisition window. Place the input RC anti-alias filter as close as possible to the AIN pin; a 100 Ω series resistor with a 1 nF capacitor to ground gives a 1.6 MHz third-order-noise filter while keeping bandwidth well above the sample rate.
Do not float the RANGE pin - it selects input span and must be tied to VDD for ±10 V bipolar range or to GND for 0-2.5 V single-ended range. Do not let the BUSY pin float when using the serial interface; pull it up through a 100 kΩ resistor to VDD if unused. Avoid driving the SAR analog input through long capacitive traces - the sample-and-hold acquisition time is short (estimated ~250 ns at 250 kSPS), so excessively long traces cause gain error and distortion.
Keep the analog-input trace, the reference decoupling, and the REF_OUT trace all on the analog side of the AGND-DGND bridge. Do not route the SCLK, DOUT, BUSY, and CS traces parallel to or under analog traces; route them on the opposite side of the board or shield them with a ground trace. Place the REF_OUT 10 µF tantalum + 0.1 µF ceramic decoupling cluster as close to the REF_OUT pin as possible; this internal reference drives the entire conversion accuracy.
For best SFDR performance, drive the AIN pin through a low-noise, low-distortion buffer such as the OPA1611 or OPA2227. Estimated: the converter's 100 dB SFDR ceiling cannot be achieved if the source amplifier's distortion exceeds -110 dB. If the converter is fed directly from a high-impedance transducer output, add a buffer; otherwise the source impedance interacts with the SAR's input sampling capacitor to cause harmonic distortion. Always terminate the analog source with a precision RC anti-aliasing filter.
Compliance Information
RoHS, REACH, lead-free, and halogen-free status per TI ADS7811 product page and supplier datasheet pages; the /1KG4 suffix explicitly indicates the part is lead-free and Green-compliant.
