Part A
ADS1251U/2K5
Texas Instruments
- Lifecycle
- Active
- Stock
- 4208 Stückzahl
- Package
- SOIC-8
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Replacement verdict
Not a drop-in replacement
The ADS1231IDR and ADS1251U/2K5 are both 24-bit delta-sigma ADCs, but they differ fundamentally in resolution architecture, input configuration, interface timing, and package footprint, so the ADS1251U/2K5 cannot be used as a direct drop-in substitute for the ADS1231IDR without redesign of the analog front end, digital interface, and PCB layout.
Different input architecture
Different output data rate
Different package footprint
Different interface timing
Parts at a glance
Part B
ADS1231IDR
Texas Instruments
- Lifecycle
- Active
- Stock
- 4314 Stückzahl
- Package
- SOIC-16
- Series
- Datenerfassung mit Analog to Digital Converters (ADC)
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADS1231IDR | ADS1251U/2K5 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit delta-sigma ADCs, so resolution alone does not differentiate them for substitutability. |
| Number of input channels | 1 (differential) | 1 (differential) | Both provide a single differential input, so channel count is equivalent for single-sensor designs. |
| Data rate (SPS) | 10 or 80 | Up to 20k | The ADS1251 supports much higher output rates, making it suitable for faster signals while the ADS1231 targets slow, high-resolution measurements. |
| Interface | Serial (SPI-compatible, 2-wire) | Serial (SPI-compatible) | Both use a simple serial interface, but pin/timing details differ, affecting drop-in compatibility. |
| Supply voltage | 2.7 V to 5.3 V | 4.75 V to 5.25 V | The ADS1231 operates over a wider low-voltage range, while the ADS1251 requires a regulated 5 V supply. |
| Internal PGA / gain | Fixed gain 128 | No PGA (fixed gain 1) | The ADS1231 includes a fixed gain stage suited to low-level bridge sensors, whereas the ADS1251 needs external amplification for small signals. |
| Package | SOIC-8 | SOIC-8 | Identical package footprint allows board-level interchangeability if surrounding circuitry is compatible. |
| Operating temperature range | -40 °C to +85 °C | -40 °C to +85 °C | Equivalent temperature ratings mean both suit the same industrial environments. |
| Typical application focus | Weigh scales, bridge sensors | General-purpose high-speed data acquisition | Different design targets mean substitutability depends on whether low-noise slow sensing or higher-speed conversion is required. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS1251U/2K5 | ADS1231IDR |
|---|---|---|
| Part Status | Active | Active |
| Number of Bits | 24 | 24 |
| Sampling Rate(Per Second) | 20k | 80 |
| Number of Inputs | 1 | 1 |
| Input Type | Differential | Differential |
| Data Interface | SPI | SPI |
| Configuration | ADC | ADC |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External |
| Voltage - Supply, Analog | 5V | 3V ~ 5.3V |
| Voltage - Supply, Digital | 5V | 3V ~ 5.3V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the primary functional differences between the ADS1231IDR and the ADS1251U/2K5?
The ADS1231IDR is a 24-bit, single-channel delta-sigma ADC optimized for weigh scales and bridge sensors, integrating a low-noise PGA with gains of 1, 2, 64, and 128. The ADS1251U/2K5 is a 24-bit, single-channel delta-sigma ADC with a fixed gain of 1 and a differential input, designed for general-purpose high-resolution measurement without an integrated PGA.
Do the ADS1231IDR and ADS1251U/2K5 have compatible package footprints?
No. The ADS1231IDR is supplied in an 8-pin SOIC (D) package, while the ADS1251U/2K5 is supplied in an 8-pin SOIC (U) package. Although both are 8-pin SOIC outlines, the pin functions and land patterns differ, so they are not drop-in replacements.
What are the maximum output data rates of these two ADCs?
The ADS1231IDR provides a fixed 10 SPS or 80 SPS output data rate selectable via the SPEED pin. The ADS1251U/2K5 provides a fixed 20.8 kSPS output data rate.
How do the supply voltage requirements compare?
The ADS1231IDR operates from a single 2.7 V to 5.3 V analog supply (AVDD) and a 2.7 V to 5.3 V digital supply (DVDD). The ADS1251U/2K5 operates from a single 4.75 V to 5.25 V supply (VDD).
Which device is better suited for direct bridge sensor interfacing?
The ADS1231IDR is specifically designed for bridge sensor applications because it integrates a low-noise PGA with selectable gains up to 128 and an on-chip oscillator, allowing direct connection to low-level differential bridge outputs. The ADS1251U/2K5 has a fixed gain of 1 and requires external amplification for low-level bridge signals.
Do both devices support external clocking?
The ADS1231IDR includes an internal oscillator and can also be clocked externally via the CLKIN pin. The ADS1251U/2K5 requires an external clock input on the CLK pin; it does not include an internal oscillator.
What are the input voltage ranges for these ADCs?
The ADS1231IDR accepts a differential input within its PGA gain settings, with the absolute input voltage constrained by the analog supply and the PGA configuration. The ADS1251U/2K5 accepts a differential input voltage of ±VREF/2 with a fixed gain of 1, where VREF is the external reference voltage.
Are these devices pin-to-pin or functionally interchangeable in an existing design?
No. The ADS1231IDR and ADS1251U/2K5 differ in package pinout, supply requirements, data rate, gain architecture, and clocking scheme. Substitution requires a full schematic and layout review against the respective manufacturer datasheets.