Part A
ADS1281IPW
德州儀器
- Lifecycle
- Active
- Stock
- 4383 件
- Package
- TSSOP-24
- Series
- 資料獲取-模數轉換器（ADC）
Replacement verdict
Not a drop-in replacement
The ADS1281IPW and ADS1208IPWR are not functionally interchangeable. The ADS1281IPW is a high-resolution 31-bit delta-sigma ADC with a serial SPI interface in a TSSOP-28 package, while the ADS1208IPWR is a 16-bit delta-sigma modulator with a different output format and a smaller TSSOP-16 footprint. Their resolution, output interface, channel architecture, and package pinout differ fundamentally, so substituting one for the other would require a complete redesign of the surrounding circuitry and layout.
Different resolution class
Different output interface
Different package footprint
Different channel architecture
Parts at a glance
Part B
ADS1208IPWR
德州儀器
- Lifecycle
- Active
- Stock
- 7626 件
- Package
- TSSOP-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 | ADS1281IPW | ADS1208IPWR | Why it matters |
|---|---|---|---|
| Resolution (bits) | 31 | 16 | Resolution determines the smallest signal change the ADC can distinguish; a 31-bit delta-sigma converter offers far finer measurement granularity than a 16-bit device. |
| Architecture | Delta-sigma (high-resolution) | Delta-sigma (modulator) | The ADS1281 is a complete high-resolution ADC with digital filter, while the ADS1208 is a modulator-only device requiring external digital filtering, affecting system design and substitutability. |
| Number of input channels | 1 (differential) | 1 (differential) | Both are single-channel differential devices, so channel count is compatible for direct substitution in single-sensor designs. |
| Output interface | SPI (serial) | Serial bit-stream modulator output | The output format dictates how the host processor reads data; the ADS1281 provides framed SPI data while the ADS1208 outputs a raw modulator bitstream needing external decimation. |
| Supply voltage (analog) | 5 V (analog), 3.3 V (digital) | 5 V (analog), 3.3 V (digital) | Matching supply rails simplify board-level replacement, though the ADS1281 requires separate analog and digital supplies. |
| Package | TSSOP-24 | TSSOP-16 | Different pin counts and footprints mean the two parts are not drop-in compatible and require PCB layout changes. |
| Operating temperature range | -40°C to +85°C | -40°C to +85°C | Identical industrial temperature ratings ensure both parts suit the same environmental conditions. |
| Data rate / output word rate | Up to 4 kSPS | Up to 40 kSPS (modulator clock dependent) | Output data rate affects achievable measurement bandwidth and noise; the ADS1208 modulator can support higher raw rates but requires external filtering. |
| Typical application focus | Seismic, energy exploration, high-resolution instrumentation | Motor control, current sensing, isolated measurement | The intended application domains differ significantly, indicating the parts are not functionally interchangeable despite sharing delta-sigma topology. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS1281IPW | ADS1208IPWR |
|---|---|---|
| Supplier | - | Texas Instruments,Rochester Electronics, LLC |
| Part Status | Active | Obsolete |
| Type | - | Modulator |
| Number of Channels | - | 1 |
| Resolution(Bits) | - | 16 b |
| Sampling Rate(Per Second) | 4k | 40k |
| Data Interface | SPI | Serial |
| Voltage Supply Source | - | Analog and Digital |
| Voltage - Supply | - | 2.7V ~ 5.5V, 4.5V ~ 5.5V |
| Operating Temperature | -40°C ~ 85°C | -40°C ~ 85°C |
| Mounting Type | - | Surface Mount |
| Number of Bits | 31 | - |
| Number of Inputs | 1 | - |
| Input Type | Differential, Single Ended | - |
| Configuration | ADC | - |
| Number of A/D Converters | 1 | - |
| Architecture | Sigma-Delta | - |
| Reference Type | External | - |
| Voltage - Supply, Analog | 5V | - |
| Voltage - Supply, Digital | 1.65V ~ 3.6V | - |
Frequently asked questions
What are the primary functional differences between the ADS1281IPW and ADS1208IPWR?
The ADS1281IPW is a single-channel, 31-bit delta-sigma analog-to-digital converter designed for high-resolution seismic and energy exploration applications, featuring a programmable gain amplifier and selectable data rates up to 4 kSPS. The ADS1208IPWR is a single-channel, 16-bit delta-sigma modulator with a digital filter interface, intended for isolated current and voltage sensing in motor control and industrial applications, offering a fixed 10 MHz clock and a 78 kSPS output rate. They differ fundamentally in resolution, architecture, and target application.
Are the ADS1281IPW and ADS1208IPWR pin-to-pin compatible?
No. The ADS1281IPW is supplied in a 24-pin TSSOP (PW) package, while the ADS1208IPWR is supplied in a 16-pin TSSOP (PW) package. The differing pin counts and pin functions preclude direct pin-to-pin substitution without PCB redesign.
Can the ADS1208IPWR directly replace the ADS1281IPW in an existing design?
No. Beyond package and pin count differences, the devices have incompatible digital interfaces and output formats. The ADS1281IPW provides a serial SPI-compatible interface with 31-bit conversion results, whereas the ADS1208IPWR outputs a 1-bit delta-sigma modulator stream requiring an external digital filter. Direct replacement is not possible without significant hardware and firmware changes.
What are the respective supply voltage requirements for these two devices?
The ADS1281IPW operates from an analog supply (AVDD) of 5 V and a digital supply (DVDD) of 3.3 V, with a separate unipolar or bipolar analog input range. The ADS1208IPWR operates from a single 5 V supply (AVDD and DVDD both at 5 V nominal). Designers must verify supply sequencing and decoupling per each datasheet.
Which device is better suited for high-resolution seismic data acquisition?
The ADS1281IPW is specifically designed for high-resolution seismic and energy exploration systems, offering 31-bit resolution, low noise, and a programmable gain amplifier. The ADS1208IPWR, with 16-bit modulator resolution and a fixed output rate, is intended for isolated current/voltage sensing and is not optimized for seismic-grade resolution. For seismic acquisition, the ADS1281IPW is the appropriate choice.
Do both devices support isolated signal sensing applications?
The ADS1208IPWR is commonly used with external isolation components (e.g., digital isolators) for isolated current and voltage sensing in motor control and industrial drives, as its modulator output can be isolated before digital filtering. The ADS1281IPW is a complete ADC with an SPI interface and is not specifically characterized for isolated sensing architectures. Isolation capability depends on the external system design, not solely on the converter.
What are the maximum output data rates for each converter?
The ADS1281IPW supports programmable data rates up to 4 kSPS. The ADS1208IPWR provides a modulator output at a 10 MHz clock with a 78 kSPS output rate after appropriate digital filtering. These rates reflect fundamentally different architectures and cannot be compared directly without considering the external filter and application requirements.