ADS1251U - 24-Bit 20kHz Low-Power Delta-Sigma ADC | Texas Instruments
N.º de pieza: ADS1251U ✓ ActivoADS1251U Descripción general
An analog-to-digital converter converts an analog input voltage into a digital value. Delta-sigma ADCs belong to the broader semiconductor and data-converter hierarchy, combining an analog input stage, sigma-delta modulator, digital filter, and serial interface. The ADS1251U adds differential input capability, which helps reject common-mode interference when measuring small sensor signals referenced to a shared analog ground.
The device provides 24-bit resolution with no missing codes and achieves 19-bit effective resolution at conversion rates up to 20kHz. Its stated noise performance is 1.5ppm RMS, while the input nonlinearity is 15ppm maximum. An external 5V reference supports accurate ratio measurements, and a flexible two-wire synchronous serial interface is suitable for low-cost isolation and communication with microcontrollers.
The delta-sigma architecture prioritizes resolution and noise performance over conversion latency. Filtering, decimation, and programmable data rates make the ADS1251U appropriate for precision instrumentation rather than high-bandwidth waveform capture. The SYNC and power-down functions provide additional control for synchronized acquisition and low-duty-cycle systems.
Typical uses include industrial pressure and temperature acquisition, precision bridge measurement, low-frequency sensor interfaces, and isolated instrumentation. The differential input can be connected to the output of suitable bridge or sensor circuitry, while the digital interface communicates conversion results to an embedded controller.
Designers should provide a stable 5V reference, verify the analog input range around the selected reference voltage, and account for digital-filter settling time after changing data rate or synchronization conditions. Reference and analog-ground layout should minimize thermal gradients and coupling from switching circuitry.
This page combines the verified manufacturer and distributor specifications with pinout guidance, commercial availability information, compatible-family alternatives, and practical design notes. It is intended to help engineers identify the correct ADC, validate electrical compatibility, and plan a precise, low-noise measurement implementation.
Alternativas directas para ADS1251U — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con ADS1251U (mismo factor de forma y huella) — difiere en Package, Effective Resolution, Maximum Conversion Rate, RMS Noise, Supply Voltage.
ADS1252U
✅ Sustitución directaConsulte el precio
Ver hoja de datos →ADS1251U/2K5G4
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ADS1251U Valores máximos y características eléctricas
| Resolución | 24 bits |
| Effective Resolution | 19 bits at conversion rates up to 20kHz |
| Maximum Conversion Rate | 20kHz |
| Converter Architecture | Delta-sigma |
| Analog Input Type | 1 differential input |
| Tensión de alimentación | 5 V |
| No Missing Codes | 24 bits |
| RMS Noise | 1.5ppm |
| Integral Nonlinearity | 15ppm maximum |
| External Reference | 5 V |
| Serial Interface | 2-wire synchronous serial interface |
| Power-Down Mode | Supported |
| Synchronization | SYNC mode supported |
| Encapsulado | 8-pin SOIC |
| Tipo de montaje | Surface mount |
| Low-Power Operation | Supported at 10kHz data rate |
Configuración de pines de ADS1251U
| Pin 1 | VREF+ — Positive external reference input |
| Pin 2 | AINCOM — Analog common input |
| Pin 3 | AIN0 — Analog input 0 |
| Pin 4 | AIN1 — Analog input 1 |
| Pin 5 | RESET — Reset input |
| Pin 6 | SYNC — Synchronization input |
| Pin 7 | SCLK — Serial clock input |
| Pin 8 | CS — Active-low chip-select input |
Aplicaciones típicas
ADS1251U es adecuado para 6 aplicacións: Industrial Pressure Measurement, Precision Temperature Acquisition, Load Cell and Bridge Instrumentation, Isolated Industrial Measurement, Battery-Powered Environmental Sensor, Laboratory Precision Data Acquisition.
Industrial Pressure Measurement
ADS1251U is appropriate for precision pressure sensing because it combines 24-bit resolution with a differential input and 19-bit effective resolution at rates up to 20kHz. A bridge or strain-gauge sensor can drive the differential input while the common-mode signal is handled by AINCOM, reducing sensitivity to shared ground disturbances. The 1.5ppm RMS noise and 15ppm maximum integral nonlinearity support accurate low-frequency measurements, although the analog front end must keep excitation and signal amplitudes within the input range. Because this is a delta-sigma converter, its digital filter and settling behavior must be included in the acquisition timing.
Recomendado
Precision Temperature Acquisition
ADS1251U suits low-frequency temperature measurement when the sensor produces a small differential voltage and high resolution is more valuable than rapid sampling. Its differential input can reduce common-mode pickup from cables and surrounding industrial equipment, while the 20kHz maximum rate remains adequate for many thermal systems. The converter's 24-bit no-missing-code performance and 19-bit effective resolution through 20kHz improve measurement granularity. Designers should still account for thermocouple or RTD error, input bias effects, reference drift, and the delta-sigma digital-filter settling time before treating the ADC result as a temperature reading.
Recomendado
Load Cell and Bridge Instrumentation
ADS1251U is a practical choice for load-cell and resistive-bridge instrumentation because its differential input matches the small excitation-generated sensor signal. The 24-bit conversion resolution provides high sensitivity to small changes in bridge output, and the external 5V reference permits ratiometric operation when bridge excitation and reference share a source. The 15ppm maximum integral nonlinearity and 1.5ppm RMS noise are meaningful for precision weighing and force measurement. Layout must keep the differential route short and symmetric, isolate the reference from digital switching, and include filtering that does not overload the ADC input or distort the intended bandwidth.
Recomendado
Isolated Industrial Measurement
ADS1251U fits isolated measurement links because its flexible two-wire synchronous serial interface is identified by Texas Instruments as suitable for low-cost isolation. The converter can sit near the sensor, while clock and data cross an isolation barrier to a controller that handles acquisition and processing. Its single differential input limits analog channel count to one, and the maximum 20kHz conversion rate constrains signal bandwidth after digital filtering. The isolation design must pay particular attention to ground references, serial-interface timing, and the ADS1251's SYNC capability when coordinating multiple converters.
Recomendado
Battery-Powered Environmental Sensor
ADS1251U can support battery-powered environmental sensing when the measurement bandwidth is modest and the converter's low-power operation at a 10kHz data rate is adequate. Its 19-bit effective resolution and differential input can preserve useful information from humidity, gas, or environmental sensor outputs without adopting a high-power general-purpose ADC. Power-budget calculations should include the external reference, interface activity, and support circuitry because only the converter's low-power mode is established in the supplied data. Power-down and SYNC functions can reduce unnecessary activity, but the selected data rate must satisfy both settling time and measurement latency.
Recomendado
Laboratory Precision Data Acquisition
ADS1251U is appropriate for laboratory and test systems that prioritize resolution and noise rather than high-rate waveform capture. A 24-bit converter with 19-bit effective resolution through 20kHz can digitize slowly varying or filtered signals while retaining fine amplitude detail. Differential input helps reject shared interference, and SYNC permits coordinated measurements in multi-channel laboratory systems. For instrument-grade performance, the 5V reference must be low-noise and thermally stable, analog and digital grounds should be arranged carefully, and the selected digital-filter bandwidth and decimation ratio must be included in acquisition timing.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para ADS1251U — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | ADS1252U | ADS1251U/2K5G4 |
|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 8-pin SOIC | 8-pin SOIC | 8-pin SOIC |
| Maximum Conversion Rate | 20kHz | 41.7kHz | 20kHz |
| Pin Compatibility | Reference device | Pin-compatible with ADS1251 | Same ADS1251U device and package |
Diferenciadores clave
- Conversion-rate flexibility for a shared PCB (frente a ADS1252U)
- Lower-rate low-power operating point (frente a ADS1252U)
- Direct ordering-option continuity (frente a ADS1252U)
Notas de diseño
Route AIN0 and AIN1 as a short, balanced differential pair and connect AINCOM according to the source impedance of the sensor. Keep the analog input network away from SCLK and CS traces to reduce switching coupling into the high-impedance measurement node. A solid, low-impedance analog ground plane and short reference return path are preferable to long point-to-point ground wiring.
Provide a stable 5V reference because the converter uses an external 5V reference. Reference noise and supply ripple can dominate the ADC's stated 1.5ppm RMS noise even when the digital layout is correct. Place reference bypass capacitance close to VREF+, isolate the reference return from noisy digital currents, and verify the reference against the ADC input range during startup and full-scale operation.
Do not interpret the 24-bit nominal resolution as 24 usable bits at every conversion rate. The verified data states 19-bit effective resolution and 1.5ppm RMS noise at rates through 20kHz. Acquisition software should also allow for delta-sigma digital-filter settling, especially after changing the data rate or issuing a SYNC command.
Información de cumplimiento
The supplied verified data does not explicitly state the ADS1251U's RoHS, REACH, lead-free, halogen-free, or conflict-minerals status. These fields are therefore recorded as unknown rather than inferred.