Part A
ADS8685IPWR
Texas Instruments
- Lifecycle
- Active
- Stock
- 3202 PCS
- Series
- Acquisition de données - Convertisseur analogique - numérique (ADC)
Replacement verdict
Compatible functional replacement candidate
The ADS8685IPWR and ADS8688IDBTR share the same 16-bit SAR ADC architecture, SPI interface, and TSSOP-16 footprint, making the ADS8685IPWR a viable functional substitute for the ADS8688IDBTR in single-channel or reduced-channel applications. However, the ADS8688IDBTR provides eight input channels versus the single channel of the ADS8685IPWR, so designers must confirm that the reduced channel count is acceptable for their system requirements before substituting.
Channel Count
Validation required
Resolution
High match
Package Type
High match
Interface Type
High match
Parts at a glance
Part B
ADS8688IDBTR
Texas Instruments
- Lifecycle
- Active
- Stock
- 1493 PCS
- Package
- TSSOP-38
- Series
- Acquisition de données - Convertisseur analogique - numérique (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 | ADS8688IDBTR | Why it matters |
|---|---|---|---|
| Number of ADC Channels | 1 (single-ended) | 8 (single-ended) | Channel count determines how many independent analog signals can be measured; a single-channel device cannot replace a multi-channel one in multiplexed systems. |
| Resolution | 16 bit | 16 bit | Both offer 16-bit resolution, so measurement precision and LSB size are equivalent, supporting similar accuracy requirements. |
| Maximum Sample Rate | 500 kSPS | 500 kSPS | Sample rate sets the maximum signal bandwidth that can be captured; identical rates mean comparable dynamic performance for fast signals. |
| Input Voltage Range | Bipolar ±10.24 V, ±5.12 V, ±2.56 V (programmable) | Bipolar ±10.24 V, ±5.12 V, ±2.56 V (programmable) | Programmable bipolar ranges allow direct connection to industrial signals without external conditioning; matching ranges preserve interface compatibility. |
| Supply Voltage | 5 V analog supply, 1.65 V to 5 V digital I/O | 5 V analog supply, 1.65 V to 5 V digital I/O | Supply requirements affect power design and logic-level interfacing; identical supplies simplify drop-in substitution. |
| Interface Type | SPI (serial) | SPI (serial) | A matching SPI interface allows the same host controller and firmware protocol to be reused across both parts. |
| Package | TSSOP-16 (PW) | TSSOP-38 (DBT) | Package footprint and pin count differ, so PCB layout and land pattern must be redesigned; the parts are not footprint-compatible. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical industrial temperature ratings ensure both parts suit the same environmental conditions. |
| Internal Reference | Integrated 4.096 V reference | Integrated 4.096 V reference | An on-chip reference reduces external component count and ensures consistent full-scale accuracy across both devices. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS8685IPWR | ADS8688IDBTR |
|---|---|---|
| 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 ADS8688IDBTR?
The ADS8685IPWR is a single-channel, 16-bit SAR ADC with a bipolar input range of ±10.24 V, while the ADS8688IDBTR is an 8-channel, 16-bit SAR ADC with independently programmable bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V. Both integrate an analog front-end with programmable gain, but the ADS8688IDBTR includes an 8-channel input multiplexer, whereas the ADS8685IPWR has a single analog input.
Are the ADS8685IPWR and ADS8688IDBTR pin-to-pin or package compatible?
No. The ADS8685IPWR is supplied in a 16-pin TSSOP (PW) package, while the ADS8688IDBTR is supplied in a 38-pin TSSOP (DBT) package. The different pin counts and pin functions prevent direct PCB footprint interchangeability without a layout redesign.
Do both devices support the same digital interface?
Yes. Both the ADS8685IPWR and ADS8688IDBTR support an SPI-compatible serial interface for configuration and data readback, allowing connection to common host controllers and FPGAs using standard SPI timing.
What are the maximum sampling rates of the ADS8685IPWR and ADS8688IDBTR?
The ADS8685IPWR supports a maximum throughput of 500 kSPS. The ADS8688IDBTR supports a maximum throughput of 500 kSPS per channel when using the multiplexer, with the same 500 kSPS aggregate conversion rate specified in the datasheet.
Can the ADS8688IDBTR be used as a drop-in replacement for the ADS8685IPWR in an existing single-channel design?
No. Although both are 16-bit SAR ADCs with integrated analog front-ends, the ADS8688IDBTR has a different package, pinout, and an 8-channel multiplexer. A single-channel design using the ADS8685IPWR would require PCB redesign and firmware changes to accommodate the ADS8688IDBTR.
What input voltage ranges do these ADCs support?
The ADS8685IPWR supports a bipolar input range of ±10.24 V. The ADS8688IDBTR supports software-selectable bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V per channel, providing greater flexibility for multi-sensor systems.
Do both devices include an internal reference and reference buffer?
Yes. Both the ADS8685IPWR and ADS8688IDBTR integrate an internal reference and reference buffer, reducing external component count and simplifying the analog front-end design for precision measurement applications.