Part A
ADS1251U
Texas Dụng cụ
- Lifecycle
- Active
- Stock
- 2748 PCS
- Package
- SOIC-8
- Series
- Data Acquisition - Analog to Digital Converters (ADC)
Replacement verdict
Not a drop-in replacement
The ADS1251U and ADS1211UG4 are both 24-bit delta-sigma ADCs, but they differ fundamentally in resolution architecture, channel count, interface type, and package footprint. The ADS1251U is a single-channel, 24-bit ADC with a serial SPI-compatible interface in an SOIC-8 package, while the ADS1211UG4 is a 4-channel, 24-bit ADC with a parallel interface in a 28-pin SOIC package. These differences in channel count, digital interface, and physical footprint make them non-interchangeable without significant redesign of the host system.
Different channel count
Different interface type
Different package footprint
Different input configuration
Parts at a glance
Part B
ADS1211UG4
Texas Dụng cụ
- Lifecycle
- Active
- Stock
- 7896 PCS
- Package
- SOIC-24
- Series
- Data Acquisition - 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 | ADS1251U | ADS1211UG4 | Why it matters |
|---|---|---|---|
| Resolution (bits) | 24 | 24 | Both are 24-bit delta-sigma ADCs, so resolution alone does not distinguish them for substitutability. |
| Number of input channels | 1 (single-ended) | 4 (differential) / 8 (single-ended) | Channel count determines how many signals can be measured; the ADS1211 supports multi-channel systems while the ADS1251 is single-channel only. |
| Maximum data rate (SPS) | 20k | 1.05k | Data rate affects achievable sampling bandwidth; the ADS1251 is much faster, which matters for higher-speed measurement applications. |
| Interface type | SPI (serial) | SPI (serial) | Both use a serial SPI-compatible interface, easing digital-side drop-in compatibility. |
| Supply voltage (analog) | 5 V (single supply) | 5 V (single supply) | Matching analog supply simplifies power-rail reuse when considering substitution. |
| Package / pin count | SOIC-8 | SOIC-24 | Different package and pin count means the parts are not footprint-compatible and require board redesign to swap. |
| Input configuration | Differential | Differential (multiplexed) | Both support differential inputs, but the ADS1211 adds an input multiplexer for multiple channels. |
| Internal PGA gain | No (fixed gain) | Yes (programmable gain amplifier) | A PGA allows scaling of small signals; the ADS1211 offers programmable gain while the ADS1251 does not. |
| Operating temperature range | -40°C to +85°C | -40°C to +85°C | Identical industrial temperature range means both suit the same environmental conditions. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS1251U | ADS1211UG4 |
|---|---|---|
| Supplier | - | Texas Instruments |
| Part Status | Active | Discontinued at Digi-Key |
| Number of Bits | 24 | 24 |
| Sampling Rate(Per Second) | 20k | 16k |
| Number of Inputs | 1 | 4 |
| Input Type | Differential | Differential |
| Data Interface | SPI | SPI |
| Configuration | ADC | MUX-PGA-ADC |
| Number of A/D Converters | 1 | 1 |
| Architecture | Sigma-Delta | Sigma-Delta |
| Reference Type | External | External, Internal |
| Voltage - Supply, Analog | 5V | 5V |
| Voltage - Supply, Digital | 5V | 5V |
| Features | - | PGA |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
Frequently asked questions
What are the key architectural differences between the ADS1251U and ADS1211UG4?
The ADS1251U is a single-channel, 24-bit delta-sigma ADC with a fixed data rate of 20 kSPS and a serial interface, offered in an SOIC-8 package. The ADS1211UG4 is a 4-channel (2 differential/4 single-ended), 24-bit delta-sigma ADC with a programmable gain amplifier (PGA) and a programmable data rate up to 15.6 kSPS, housed in a 24-pin SOIC package. The ADS1211UG4 integrates more channels and a PGA, while the ADS1251U provides a simpler, higher-speed single-channel signal path.
Can the ADS1251U be used as a direct drop-in replacement for the ADS1211UG4?
No. The two devices differ in package (SOIC-8 vs 24-pin SOIC), pin count, pin functions, channel count, and digital interface protocol. A direct drop-in replacement is not possible; any substitution requires a PCB redesign and firmware changes validated against the respective datasheets.
How do the maximum data rates of the ADS1251U and ADS1211UG4 compare?
The ADS1251U provides a fixed 20 kSPS output data rate. The ADS1211UG4 offers a programmable data rate with a maximum of 15.6 kSPS. The ADS1251U therefore supports a higher maximum throughput, while the ADS1211UG4 allows the user to trade speed for noise performance via its programmable rate.
Do both devices include a programmable gain amplifier (PGA)?
No. The ADS1211UG4 integrates a programmable gain amplifier, allowing direct amplification of low-level sensor signals. The ADS1251U does not include an on-chip PGA; external signal conditioning is required for low-level inputs.
What input channel configurations are available on each device?
The ADS1251U provides a single differential input channel. The ADS1211UG4 provides four input channels configurable as either two differential inputs or four single-ended inputs, offering greater flexibility for multi-sensor systems.
How do the digital interfaces of the ADS1251U and ADS1211UG4 differ?
The ADS1251U uses a simple synchronous serial interface for output data and clock. The ADS1211UG4 uses a serial peripheral interface with additional control registers for configuring channel selection, PGA gain, and data rate. The ADS1211UG4 therefore requires more firmware configuration than the ADS1251U.
Are the ADS1251U and ADS1211UG4 pin-compatible?
No. The ADS1251U is supplied in an 8-pin SOIC package, while the ADS1211UG4 is supplied in a 24-pin SOIC package. The pin counts, pin assignments, and package footprints differ, so they are not pin-compatible.
Which device is better suited for multi-channel data acquisition?
The ADS1211UG4 is better suited for multi-channel data acquisition because it provides four input channels (two differential or four single-ended) plus an integrated PGA. The ADS1251U is limited to a single differential channel and is better suited to single-sensor, higher-speed applications.