Part A
ADS8685IPWR
Техасские инструменты
- Lifecycle
- Active
- Stock
- 3202 ПКС
- Series
- Сбор данных - аналогово-цифровые преобразователи (ADC)
Replacement verdict
Compatible functional replacement candidate
The ADS8685IPWR and ADS8688AIDBT share the same TSSOP-16 footprint, 16-bit SAR architecture, and 5 V analog supply, making them viable functional replacement candidates. However, the ADS8685IPWR provides a single-channel input while the ADS8688AIDBT offers eight channels, and their input voltage ranges and throughput rates differ. Designers must validate channel count requirements, input range configuration, and sampling rate against the target application before substituting one for the other.
Package Type
High match
Resolution
High match
Channel Count
Not compatible
Input Voltage Range
Validation required
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 | ADS8685IPWR | ADS8688AIDBT | Why it matters |
|---|---|---|---|
| Number of Input Channels | 1 (single-ended) | 8 (single-ended) | Channel count determines how many analog signals can be measured; a single-channel device cannot replace a multi-channel one in multiplexed systems. |
| Resolution | 16 bits | 16 bits | Resolution sets the smallest detectable signal change; both are 16-bit, so quantization performance is comparable. |
| Maximum Sample Rate | 500 kSPS | 500 kSPS | Sample rate limits the bandwidth of signals that can be captured; identical rates mean similar dynamic performance for fast signals. |
| Input Voltage Range | ±10.24 V (bipolar, software-selectable ranges) | ±10.24 V (bipolar, software-selectable ranges) | Input range must match the sensor or signal amplitude; matching ranges allow direct substitution without additional signal conditioning. |
| Interface Type | SPI (serial) | SPI (serial) | The digital interface must be compatible with the host controller; both use SPI, simplifying drop-in replacement at the protocol level. |
| Supply Voltage | 5 V analog supply, 1.8 V to 5 V digital I/O | 5 V analog supply, 1.8 V to 5 V digital I/O | Supply requirements affect board-level power design; identical rails mean the same power tree can support either part. |
| Package | TSSOP-16 | TSSOP-38 | Package footprint and pin count dictate PCB layout; different packages require a board redesign and cannot be directly swapped. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Temperature range determines suitability for industrial and automotive environments; matching ranges ensure equivalent environmental robustness. |
| Internal Reference | Integrated 4.096 V reference | Integrated 4.096 V reference | An internal reference simplifies design and improves accuracy; both integrating the same reference yields comparable gain accuracy without external components. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS8685IPWR | ADS8688AIDBT |
|---|---|---|
| Part Status | Active | Active |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | - | 500k |
| Number of Inputs | 1 | 8 |
| Input Type | Pseudo-Differential, Single Ended | Differential, Single Ended |
| Data Interface | SPI | SPI |
| Configuration | PGA-S/H-ADC | PGA-MUX-S/H-ADC |
| Ratio - S / H: ADC | 1:1 | 1:1 |
| Number of A/D Converters | - | 1 |
| Architecture | SAR | SAR |
| Reference Type | External, Internal | External, Internal |
| Voltage - Supply, Analog | 5V | 5V |
| Voltage - Supply, Digital | 1.65V ~ 5.25V | 1.65V ~ 5.25V |
| Features | PGA | PGA |
| Operating Temperature | -40°C ~ 125°C (TA) | -40°C ~ 125°C |
| Base Product Number | ADS8685 | - |
| Sampling Rate (Per Second) | 500k | - |
| Number of A / D Converters | 1 | - |
| Mounting Type | Surface Mount | - |
| Packaging | Cut Tape (CT), Tape & Reel (TR) | - |
Frequently asked questions
What are the key architectural differences between the ADS8685IPWR and ADS8688AIDBT?
The ADS8685IPWR is a single-channel, 16-bit SAR ADC with a bipolar input range of ±10.24 V, while the ADS8688AIDBT is an 8-channel, 16-bit SAR ADC with software-selectable bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V. The ADS8685 integrates an analog front-end with a programmable gain amplifier and a 4.096 V reference, whereas the ADS8688A includes an 8-channel input multiplexer with an integrated AFE and reference.
Are the ADS8685IPWR and ADS8688AIDBT pin-compatible?
No. The ADS8685IPWR is offered in a 16-pin TSSOP (PW) package, while the ADS8688AIDBT is offered in a 38-pin TSSOP (DBT) package. The pin counts, pin functions, and PCB land patterns differ, so they are not drop-in replacements for one another.
Do both devices support the same digital interface?
Both devices support an SPI-compatible serial interface for configuration and data readback. However, the ADS8688AIDBT requires additional command handling for channel selection and sequencer configuration due to its 8-channel multiplexer, whereas the ADS8685IPWR is a single-channel device with a simpler command set.
How do the throughput and sampling rates compare?
Both the ADS8685IPWR and ADS8688AIDBT are 16-bit SAR ADCs with a maximum throughput of 500 kSPS. For the ADS8688AIDBT, the 500 kSPS rate applies per channel when using the auto-sequencer, but the aggregate rate is shared across the eight channels.
What are the input voltage range differences between the two parts?
The ADS8685IPWR provides a fixed bipolar input range of ±10.24 V. The ADS8688AIDBT offers software-programmable bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V, allowing it to accommodate a wider variety of sensor and signal amplitudes without external conditioning.
Can the ADS8685IPWR be used as a substitute for the ADS8688AIDBT in an existing design?
Not directly. The ADS8685IPWR is a single-channel device in a 16-pin package, while the ADS8688AIDBT is an 8-channel device in a 38-pin package. Substitution would require a PCB redesign, revalidation of the input multiplexing, and confirmation that the single fixed input range meets the application requirements.
Do both devices include an integrated voltage reference?
Yes. Both the ADS8685IPWR and ADS8688AIDBT integrate an internal 4.096 V reference with low drift, eliminating the need for an external reference in most applications. Both also support the use of an external reference if higher accuracy or a different reference value is required.
What are the typical applications for each device?
The ADS8685IPWR is suited to single-channel, high-voltage bipolar signal acquisition such as industrial process control and power monitoring. The ADS8688AIDBT is suited to multi-channel data acquisition systems, such as industrial PLC analog input modules and multi-sensor monitoring, where several bipolar inputs must be digitized by a single ADC.