Part A
ADS1251U
德州儀器
- Lifecycle
- Active
- Stock
- 2748 件
- Package
- SOIC-8
- Series
- 資料獲取-模數轉換器（ADC）
Replacement verdict
Not a drop-in replacement
The ADS1251U and ADS1201UG4 are both 24-bit delta-sigma analog-to-digital converters, but they differ fundamentally in resolution architecture, output interface, input configuration, and package footprint, so neither device can directly substitute for the other without a full board and firmware redesign.
Different output interface
Different input configuration
Different package footprint
Different data rate capability
Parts at a glance
Part B
ADS1201UG4
德州儀器
- Lifecycle
- Active
- Stock
- 6830 件
- Package
- SOIC-16
- Series
- 資料獲取-ADC DAC-專用
Key differences
Rows are prioritized by design impact. Highlighted values require attention during substitution.
Key electrical and mechanical differences between the two devices
| Parameter | ADS1251U | ADS1201UG4 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit delta-sigma converters, so resolution alone does not distinguish them for substitutability. |
| Architecture | Delta-Sigma (single-channel ADC) | Delta-Sigma modulator | The ADS1251U is a complete ADC with digital filter and serial interface, while the ADS1201UG4 is a modulator-only device requiring external digital filtering, so they are not drop-in substitutes. |
| Output Interface | Serial (SPI-compatible) | Serial bit-stream (modulator output) | The output format determines what downstream logic or processor is needed; the ADS1251U provides a filtered digital word while the ADS1201UG4 outputs a raw 1-bit stream. |
| Input Type | Differential | Differential | Both accept differential inputs, which is important for rejecting common-mode noise in precision measurement applications. |
| Supply Voltage | 5 V (analog and digital) | 5 V | Matching supply requirements simplifies board-level replacement, though both operate from a 5 V rail. |
| Package | SOIC-8 | SOIC-16 | Different package footprints and pin counts mean the two parts are not physically interchangeable on the same PCB layout. |
| Data Rate / Output Word Rate | Up to ~20 kSPS | Up to ~40 kSPS (modulator clock dependent) | The achievable sample rate affects throughput in the target system and differs between the two devices. |
| On-chip Digital Filter | Yes (sinc filter included) | No (external filter required) | The ADS1251U delivers a finished conversion result, whereas the ADS1201UG4 needs an external digital filter, changing system complexity and BOM. |
| Typical Application | Precision sensor and industrial measurement | Motor control and isolated measurement modulators | Intended use cases differ, so functional substitutability depends on whether the system needs a complete ADC or a modulator front-end. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS1251U | ADS1201UG4 |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Active | Discontinued at Digi-Key |
| Type | - | Modulator |
| Number of Channels | - | 1 |
| Resolution(Bits) | - | 24 b |
| Sampling Rate(Per Second) | 20k | 1k |
| Data Interface | SPI | Serial |
| Voltage Supply Source | - | Analog and Digital |
| Voltage - Supply | - | 4.75V ~ 5.25V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | - | Surface Mount |
| Number of Bits | 24 | - |
| Number of Inputs | 1 | - |
| Input Type | Differential | - |
| Configuration | ADC | - |
| Number of A/D Converters | 1 | - |
| Architecture | Sigma-Delta | - |
| Reference Type | External | - |
| Voltage - Supply, Analog | 5V | - |
| Voltage - Supply, Digital | 5V | - |
Frequently asked questions
What are the primary differences between the ADS1251U and the ADS1201UG4?
The ADS1251U is a 24-bit delta-sigma analog-to-digital converter with a fixed data rate of 20 kSPS, while the ADS1201UG4 is a 24-bit delta-sigma modulator with a selectable data rate of 10 kSPS or 20 kSPS. The ADS1251U integrates a full ADC signal chain with a digital filter and SPI-compatible interface, whereas the ADS1201UG4 outputs a 1-bit modulator stream requiring external digital filtering.
Are the ADS1251U and ADS1201UG4 pin-compatible?
No. The ADS1251U is offered in an 8-pin SOIC package, and the ADS1201UG4 is offered in a 16-pin SOIC package. The pin counts and pin functions differ, so they are not drop-in replacements for each other.
What are the input voltage ranges of the ADS1251U and ADS1201UG4?
The ADS1251U operates with a differential input range of ±VREF, where VREF is the external reference voltage. The ADS1201UG4 also uses a differential input with a full-scale range of ±VREF. Both devices require an external voltage reference to define the measurement range.
What digital interfaces do the ADS1251U and ADS1201UG4 provide?
The ADS1251U provides a synchronous serial interface compatible with SPI for reading conversion results. The ADS1201UG4 outputs a 1-bit delta-sigma modulator data stream on a single data line, which must be processed by an external digital filter or FPGA/DSP to obtain a multi-bit conversion result.
What are the typical supply voltages for the ADS1251U and ADS1201UG4?
The ADS1251U operates from a single 5 V analog supply (AVDD) and a 2.7 V to 5.25 V digital supply (DVDD). The ADS1201UG4 operates from a 5 V analog supply and a 2.7 V to 5.5 V digital supply. Both devices are specified for industrial temperature ranges.
Which device is better suited for isolated measurement applications?
The ADS1201UG4 is often preferred for isolated measurement systems because its 1-bit modulator output can be transmitted across an isolation barrier with a single digital isolator channel, and the digital filter can be placed on the isolated or non-isolated side. The ADS1251U integrates the digital filter internally, so isolation would require isolating the full serial interface.
Can the ADS1251U and ADS1201UG4 achieve the same effective resolution?
Both devices are 24-bit delta-sigma converters, but effective resolution depends on the output data rate, filter configuration, and external components. The ADS1251U specifies 24-bit no-missing-code performance at 20 kSPS with its internal filter. The ADS1201UG4 requires an external digital filter, and its effective resolution depends on the selected filter order and decimation ratio, so the two cannot be assumed to deliver identical effective resolution without application-specific evaluation.
What are the package and operating temperature specifications for the ADS1251U and ADS1201UG4?
The ADS1251U is available in an 8-pin SOIC package and is specified over the −40°C to +85°C temperature range. The ADS1201UG4 is available in a 16-pin SOIC package and is specified over the −40°C to +85°C temperature range. Both are lead-free (RoHS-compliant) in their respective orderable part numbers.