Part A
ADS8685IPWR
Texas Instruments
- Lifecycle
- Active
- Stock
- 3202 PCS
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (ADC)
Replacement verdict
Compatible functional replacement candidate
The ADS8685IPWR and ADS8681IPWR share the same TSSOP-16 package, 16-bit SAR architecture, and pin-compatible footprint, making the ADS8685IPWR a viable functional replacement candidate for the ADS8681IPWR in most designs. The primary distinction is sampling throughput, so verify that the host interface timing and system bandwidth requirements accommodate the lower maximum sample rate before substituting in high-speed acquisition paths.
Package Type
High match
Resolution
High match
Maximum Sample Rate
Validation required
Input Interface Type
High match
Parts at a glance
Part B
ADS8681IPWR
Texas Instruments
- Lifecycle
- Active
- Stock
- 7571 PCS
- Package
- TSSOP-16
- Series
- Acquisição de dados - Analogo para Convertedores Digitais (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 | ADS8681IPWR | Why it matters |
|---|---|---|---|
| Resolution | 16 bit | 16 bit | Both are 16-bit SAR ADCs, so nominal resolution is identical and not a differentiator for substitutability. |
| Sampling Rate (max) | 500 kSPS | 1 MSPS | The ADS8681 offers twice the throughput, which matters for higher-bandwidth signal acquisition; the ADS8685 is limited to 500 kSPS. |
| Number of Input Channels | 1 (single-ended) | 1 (single-ended) | Both are single-channel devices, so channel count does not affect functional substitution. |
| Input Voltage Range | ±10.24 V (bipolar, programmable) | ±10.24 V (bipolar, programmable) | Identical programmable bipolar input ranges mean both can interface to the same sensor/signal swings without front-end redesign. |
| Interface Type | SPI (serial) | SPI (serial) | Both use a standard SPI interface, so the digital host connection is compatible between the two parts. |
| Supply Voltage (analog) | 5 V (analog), 3.3 V (digital) | 5 V (analog), 3.3 V (digital) | Matching supply rails allow drop-in replacement without changing the power tree. |
| Package | TSSOP-16 | TSSOP-16 | Same package and pinout enable direct PCB footprint compatibility. |
| Operating Temperature Range | -40 °C to +125 °C | -40 °C to +125 °C | Identical industrial temperature range means both suit the same environmental conditions. |
| INL (Integral Nonlinearity) | ±1 LSB (typ) | ±1 LSB (typ) | Equivalent linearity performance means accuracy is not degraded when substituting one for the other. |
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Full specification comparison
Use manufacturer datasheets as the final authority.
| Specification | ADS8685IPWR | ADS8681IPWR |
|---|---|---|
| Part Status | Active | Active |
| Number of Bits | 16 | 16 |
| Sampling Rate(Per Second) | - | 1M |
| Number of Inputs | 1 | 1 |
| Input Type | Pseudo-Differential, Single Ended | Pseudo-Differential, Single Ended |
| Data Interface | SPI | SPI |
| Configuration | PGA-S/H-ADC | PGA-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 (TA) |
| 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 differences between the ADS8685IPWR and ADS8681IPWR?
The ADS8685IPWR is a 16-bit, 500-kSPS SAR ADC, while the ADS8681IPWR is a 16-bit, 1-MSPS SAR ADC. Both are single-channel, bipolar-input devices in a TSSOP-16 package with an integrated analog front end, but the ADS8681IPWR offers twice the maximum throughput rate of the ADS8685IPWR.
Are the ADS8685IPWR and ADS8681IPWR pin-compatible?
Yes. Both devices are offered in the same 16-pin TSSOP (PW) package and share the same pinout, allowing the ADS8681IPWR to be used as a higher-speed drop-in option for the ADS8685IPWR when the rest of the system supports the increased throughput.
Do both devices support the same input voltage ranges?
Yes. Both the ADS8685IPWR and ADS8681IPWR feature an integrated analog front end with software-programmable bipolar input ranges of ±10.24 V, ±5.12 V, and ±2.56 V, along with a 5-V unipolar range, allowing direct connection of high-voltage signals without external conditioning.
What is the maximum sampling rate of each device?
The ADS8685IPWR supports a maximum throughput of 500 kSPS, whereas the ADS8681IPWR supports up to 1 MSPS. The higher rate of the ADS8681IPWR makes it preferable for applications requiring wider signal bandwidth or faster channel scanning.
Do both ADCs use the same digital interface?
Yes. Both devices provide a SPI-compatible serial interface with daisy-chain capability and support a dedicated SDI input for register configuration, so the digital host interface is identical between the ADS8685IPWR and ADS8681IPWR.
Are the ADS8685IPWR and ADS8681IPWR specified over the same temperature range?
Yes. Both devices are specified for operation over the industrial temperature range of –40°C to +125°C, making them suitable for the same industrial and instrumentation environments.
Can the ADS8681IPWR replace the ADS8685IPWR without firmware changes?
Because the two devices share the same package, pinout, input ranges, and SPI register interface, the ADS8681IPWR can generally replace the ADS8685IPWR without firmware changes. However, the system timing budget must be revalidated to confirm that the higher 1-MSPS throughput of the ADS8681IPWR is supported by the host and signal chain.