Part A
ADS8691IPW
Техасские инструменты
- Lifecycle
- Active
- Stock
- 7455 ПКС
- Package
- TSSOP-16
- Series
- Сбор данных - аналогово-цифровые преобразователи (ADC)
Replacement verdict
Compatible functional replacement candidate
The ADS8691IPW can serve as a functional replacement candidate for the ADS8688AIDBT in applications where a single-channel, 18-bit SAR ADC with an integrated analog front end is acceptable, but the reduced channel count, different package footprint, and narrower input voltage range require careful validation before substitution.
Channel Count
Not compatible
Package Type
Validation required
Input Voltage Range
Validation required
Resolution
High match
Parts at a glance
Part B
ADS8688AIDBT
Техасские инструменты
- Lifecycle
- Active
- Stock
- 5149 ПКС
- Package
- TSSOP-38
- Series
- Сбор данных - аналогово-цифровые преобразователи (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 | ADS8688AIDBT | ADS8691IPW | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 8 (single-ended) | 1 (single-ended) | Channel count determines how many analog signals can be sampled; an 8-channel device cannot be directly substituted where a single-channel part is used and vice versa. |
| Resolution | 16 bit | 18 bit | Higher resolution provides finer measurement granularity; an 18-bit converter offers 4x the LSB count of a 16-bit device, affecting precision-sensitive designs. |
| Sampling Rate (Max) | 500 kSPS | 1 MSPS | Maximum throughput limits the bandwidth of signals that can be digitized; the faster part supports higher-frequency inputs or faster multiplexed scanning. |
| Input Voltage Range | ±10.24 V, ±5.12 V, ±2.56 V (bipolar, software-selectable) | ±10.24 V, ±5.12 V, ±2.56 V (bipolar, software-selectable) | Programmable input ranges allow direct connection to various sensor and industrial signal levels without external conditioning. |
| Interface Type | SPI (serial) | SPI (serial) | Both use SPI, so the digital host interface is compatible, but register maps and command sets differ and firmware must be adapted. |
| Supply Voltage (Analog) | 5 V (single analog supply) | 5 V (single analog supply) | Matching analog supply simplifies power-rail design and allows reuse of the same regulator and decoupling network. |
| Package | TSSOP-38 (DBT) | TSSOP-16 (PW) | Different package footprints and pin counts prevent drop-in board replacement; a PCB redesign is required to swap these parts. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical industrial temperature ratings mean both are suitable for the same harsh-environment applications. |
| Internal Reference | Integrated 4.096 V reference | Integrated 4.096 V reference | An on-chip reference reduces external component count and board space while ensuring consistent gain accuracy. |
Need help validating a replacement?
Send your BOM and application constraints for technical and sourcing review.
Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS8691IPW | ADS8688AIDBT |
|---|---|---|
| Series | ADS869x | - |
| Part Status | Active | Active |
| Number of Bits | 18 | 16 |
| Sampling Rate(Per Second) | 1M | 500k |
| Number of Inputs | 1 | 8 |
| Input Type | Differential, Pseudo-Differential, Single Ended | Differential, Single Ended |
| Data Interface | SPI | SPI |
| Configuration | PGA-ADC | PGA-MUX-S/H-ADC |
| Ratio - S / H: ADC | 0:1 | 1:1 |
| Number of A/D Converters | 1 | 1 |
| Architecture | SAR | SAR |
| Reference Type | Internal | External, Internal |
| Voltage - Supply, Analog | 4.75V ~ 5.25V | 5V |
| Voltage - Supply, Digital | 1.65V ~ 3.3V | 1.65V ~ 5.25V |
| Features | Internal Oscillator | PGA |
| Operating Temperature | -40°C ~ 125°C | -40°C ~ 125°C |
Frequently asked questions
What are the key architectural differences between the ADS8688AIDBT and the ADS8691IPW?
The ADS8688AIDBT is an 8-channel, 16-bit successive-approximation register (SAR) analog-to-digital converter with an integrated analog front-end, offering a maximum aggregate throughput of 500 kSPS. The ADS8691IPW is a single-channel, 18-bit SAR ADC with an integrated analog front-end, capable of a maximum throughput of 1 MSPS. The ADS8688AIDBT provides eight multiplexed input channels, while the ADS8691IPW provides a single channel.
Are the ADS8688AIDBT and ADS8691IPW pin-to-pin or package compatible?
No. The ADS8688AIDBT is supplied in a 38-pin TSSOP (DBT) package, whereas the ADS8691IPW is supplied in a 16-pin TSSOP (PW) package. The two devices have different pin counts, pin functions, and PCB land patterns, so they are not drop-in replacements for one another.
What are the input voltage ranges supported by each device?
Both devices integrate a programmable analog front-end supporting bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V, as well as unipolar ranges of 0 V to 10.24 V, 0 V to 5.12 V, and 0 V to 2.56 V. The input range is selected via the device configuration registers over the SPI interface.
How do the resolution and throughput of the two ADCs compare?
The ADS8688AIDBT offers 16-bit resolution with a maximum aggregate throughput of 500 kSPS across its eight channels. The ADS8691IPW offers 18-bit resolution with a maximum throughput of 1 MSPS on its single channel. The ADS8691IPW therefore provides higher resolution and higher per-channel throughput, while the ADS8688AIDBT provides channel density.
Do both devices use the same digital interface?
Yes. Both the ADS8688AIDBT and the ADS8691IPW use a SPI-compatible serial interface for configuration and data readback, supporting daisy-chain operation. The interface logic supply range is 1.65 V to 5.25 V on both devices, allowing direct connection to common host processors.
What are the analog supply requirements for the ADS8688AIDBT and ADS8691IPW?
Both devices operate from a 5 V analog supply (AVDD) and require an additional bipolar supply for the internal analog front-end. The ADS8688AIDBT and ADS8691IPW both specify an AVDD of 5 V and use an internal charge pump or external supplies to support the bipolar input ranges. Designers should consult the respective datasheets for the exact supply rail and decoupling requirements.
Which device is better suited for multi-channel data acquisition versus high-resolution single-channel measurement?
The ADS8688AIDBT is better suited for multi-channel data acquisition systems because it integrates eight multiplexed input channels in a single package, reducing board space and component count. The ADS8691IPW is better suited for high-resolution single-channel measurement applications, such as precision instrumentation, where 18-bit resolution and 1 MSPS throughput on one channel are required.