component
ADS8681
Public Made by Adomby adom
TI 18-bit, 1 MSPS SAR ADC with integrated reference, QFN-16. Bipolar input range, SPI. Datasheet-verified.
3D Model
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Symbol & Footprint
Schematic Symbol
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PCB Footprint
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Datasheet
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README
markdownADS8681
Texas Instruments · SAR ADC · QFN-16
High-resolution 18-bit successive-approximation ADC that samples one input at up to 1 MSPS over SPI, with an integrated reference and reference buffer so the full-scale span is defined without external precision parts. A front-end that accepts true bipolar and wide unipolar input ranges lets it digitize signals directly from a sensor or amplifier without extra scaling, and an on-chip ALARM flags over-range. Aimed at precision data acquisition, test-and-measurement, and control.
Pinout
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | AGND | power_in | Analog ground pin. Decouple with the AVDD pin. |
| 2 | REFIO | bidirectional | Internal 4.096 V reference output and external reference input pin. Decouple with REFGND. |
| 3 | REFGND | power_in | Reference ground pin; short to the analog ground plane. Decouple with the REFIO and REFCAP pins. |
| 4 | REFCAP | passive | ADC reference buffer decoupling capacitor pin. Decouple with the REFGND pin. |
| 5 | AIN_P | input | Analog input: positive. Constant resistive input impedance ≥1 MΩ with overvoltage protection up to ±20 V. Decouple with the AIN_GND pin. |
| 6 | AIN_GND | input | Analog input: negative. Constant resistive input impedance ≥1 MΩ with overvoltage protection up to ±20 V. Decouple with the AIN_P pin. |
| 7 | RST | input | Active low logic input to reset the device. |
| 8 | SDI | input | Dual function: data input pin (MOSI) for serial communication; chain data input during serial communication in daisy-chain mode. |
| 9 | CONVST/CS | input | Dual-function pin. Active-high logic: CONVST rising edge starts a conversion (acquisition→conversion). Active-low logic: chip-select input; device drives the data bus when CS is low, SDO-x go tri-state when CS is high. |
| 10 | SCLK | input | Serial communication clock input pin; all system-synchronous data transfer protocols are timed with respect to SCLK. |
| 11 | SDO-0 | output | Serial communication: data output 0 (MISO). |
| 12 | SDO-1 | output | Multifunction output pin: active-high ALARM flag, data output 1 for serial communication, or general-purpose output. Function selected via configuration register. |
| 13 | RVS | output | Multifunction output pin for serial interface. With CS high, RVS reflects the internal ADCST signal; with CS low, RVS status depends on the output protocol selection. |
| 14 | DVDD | power_in | Digital supply pin (1.65 V to AVDD, nominal 3.3 V). Decouple with the DGND pin. |
| 15 | DGND | power_in | Digital ground pin. Decouple with the DVDD pin. |
| 16 | AVDD | power_in | Analog supply pin (4.75 V to 5.25 V nominal 5 V). Decouple with the AGND pin. |
Key specifications
| Parameter | Value |
|---|---|
| Type | 18-bit SAR ADC |
| Throughput | 1 MSPS |
| Input | Single-ended, bipolar/unipolar ranges |
| Interface | SPI |
| Reference | Integrated + buffer |
| Extras | ALARM over-range flag |
| Supply | AVDD 5 V, DVDD 1.65-5.5 V |
| Package | QFN-16 |
Ordering variants
ADS8681RUM (QFN-16)ADS8681IPW (TSSOP-16)
CAD (KiCad official)
- Symbol:
Analog_ADC:ADS8681RUM (KiCad official) - Footprint:
Package_DFN_QFN:QFN-16-1EP_4x4mm_P0.65mm_EP2.7x2.7mm - 3D model: QFN-16 (KiCad packages3D, STEP)
- 3D model files:
ads8681-etched.step/ads8681-etched.glbcarry the MPN laser-etched on the die in a toggleableAdom.LaserEtchgroup (Fusion-ready);ads8681.step/ads8681.glbare the bare package body.
Provenance
Data extracted from the manufacturer datasheet, not a distributor listing:
- Datasheet: Texas Instruments datasheet (75 pp, sha256
7352b44f82a9fefd, retrieved 2026-08-17, tier: manufacturer) - Extractor:
ds2sf(Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate. - CAD: KiCad official libraries (CC-BY-SA 4.0).