ADS8688IDBTR - 16-Bit 500kSPS 8-Ch SAR ADC | Texas Instruments
N.º de pieza: ADS8688IDBTR ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $18.5 | $18,50 |
| 10 | $16.8 | $168,00 |
| 100 | $14.45 | $1.445,00 |
| 500 | $12.1 | $6.050,00 |
| 1.000 | $9.85 | $9.850,00 |
ADS8688IDBTR Descripción general
A SAR (Successive-Approximation Register) ADC is a sampling architecture that converts an analog input to a digital code using a binary-search algorithm against an internal precision DAC. Compared with delta-sigma or pipeline ADCs, SAR converters offer deterministic latency, low power, and excellent multi-channel throughput, making them ideal for multiplexed data-acquisition systems in industrial control, instrumentation, and motor-drive applications where the control loop must react within a known time after each conversion.
Key features include ±1-LSB (max) linearity, a low-noise 4-ppm/°C internal reference, an SPI-compatible daisy-chainable serial interface, and a 1.65-V to 5.25-V digital supply that allows direct connection to most host MCUs and FPGAs without level translators. An on-chip input protection clamp handles ±20-V over-voltage on every analog input channel.
The architecture pairs a charge-redistribution SAR core with a high-bandwidth input driver, allowing true ±10-V bipolar measurements from a single 5-V rail - a key advantage in legacy industrial systems where the signal swings can exceed the supply. Per-channel range scaling lets the designer optimize dynamic range for each transducer type, and a hardware reset pin and daisy-chain logic simplify synchronization when stacking multiple ADS8688/ADS8684 devices on the same SPI bus.
Typical applications include PLC analog input modules, multi-axis motor-drive feedback, industrial process-control transmitters, power-metering front-ends, and multi-channel data-acquisition cards for test and measurement equipment. The 8-channel integration cuts board area versus discrete ADCs and reduces BOM cost.
When designing with this device, place the 10-µF AVDH bypass capacitor within 5 mm of the AVDH pin and route AVDD separately from DVDD to avoid digital noise coupling into the analog front-end. For best THD in audio-bandwidth front ends, average the per-channel offset calibration coefficients programmed into each channel's OFFSET register at power-up.
This page synthesizes distributor pricing, drop-in same-package alternatives, and layout guidance that complements the manufacturer datasheet to accelerate multi-channel data-acquisition design.
Alternativas directas para ADS8688IDBTR — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con ADS8688IDBTR (mismo factor de forma y huella) — difiere en Analog Supply Voltage (AVDD), Input Overvoltage Protection, MSL Level, Operating Temperature Range, Package.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
ADS8688IDBT
✅ Sustitución directa✓ En stock
$15.6 / unidad
Ver hoja de datos →ADS8688IDBTR-Q1
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ADS8684IDBTR
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
ADS8688IDBTR Valores máximos y características eléctricas
| Resolución | 16 bits |
| Number of Channels | 8 input, 1 SAR core |
| Frecuencia de muestreo | 500 kSPS |
| ADC Architecture | SAR (Successive Approximation Register) |
| Analog Supply Voltage (AVDD) | 5 V (typical) |
| Digital Supply Voltage (DVDD) | 1.65 V to 5.25 V |
| Bipolar Input Ranges | ±10.24 V, ±5.12 V, ±2.56 V |
| Unipolar Input Ranges | 0 V to 10.24 V, 0 V to 5.12 V |
| Integrated Reference | Yes, 4.096 V internal |
| Interfaz | SPI-compatible, daisy-chain capable |
| Input Overvoltage Protection | ±20 V on each analog input |
| Integral Non-Linearity (INL) | ±1 LSB (max) |
| Rango de temperatura de funcionamiento | -40°C to +125°C |
| Encapsulado | 38-pin TSSOP (DBT), 9.7 mm x 6.4 mm |
| Tipo de montaje | Surface Mount |
| Nivel MSL | 2 (1 year floor life) |
| Estado RoHS | Compliant |
Configuración de pines de ADS8688IDBTR
| Pin 1 | AVDD — Analog supply, 5 V typical |
| Pin 2 | AGND — Analog ground |
| Pin 3 | AVDD — Analog supply, 5 V typical |
| Pin 4 | AIN_P — Analog input, positive input (per range config) |
| Pin 5 | AIN_GND — Analog input reference ground |
| Pin 6 | REFCAP — Internal reference bypass capacitor |
| Pin 7 | REFIO — Internal/external reference voltage output or input |
| Pin 8 | AGND — Analog ground |
| Pin 9 | AIN0P — Analog input channel 0, positive |
| Pin 10 | AIN0M — Analog input channel 0, negative (AGND) |
| Pin 11 | AIN1P — Analog input channel 1, positive |
| Pin 12 | AIN1M — Analog input channel 1, negative (AGND) |
| Pin 13 | AIN2P — Analog input channel 2, positive |
| Pin 14 | AIN2M — Analog input channel 2, negative (AGND) |
| Pin 15 | AIN3P — Analog input channel 3, positive |
| Pin 16 | AIN3M — Analog input channel 3, negative (AGND) |
| Pin 17 | AIN4P — Analog input channel 4, positive |
| Pin 18 | AIN4M — Analog input channel 4, negative (AGND) |
| Pin 19 | AIN5P — Analog input channel 5, positive |
| Pin 20 | AIN5M — Analog input channel 5, negative (AGND) |
| Pin 21 | AIN6P — Analog input channel 6, positive |
| Pin 22 | AIN6M — Analog input channel 6, negative (AGND) |
| Pin 23 | AIN7P — Analog input channel 7, positive |
| Pin 24 | AIN7M — Analog input channel 7, negative (AGND) |
| Pin 25 | AGND — Analog ground |
| Pin 26 | AGND — Analog ground |
| Pin 27 | DVDD — Digital supply, 1.65 V to 5.25 V |
| Pin 28 | DGND — Digital ground |
| Pin 29 | SCLK — Serial-clock input (SPI) |
| Pin 30 | SDI — Serial-data input (SPI MOSI) |
| Pin 31 | SDO — Serial-data output (SPI MISO) |
| Pin 32 | CS — Chip-select input (active low) |
| Pin 33 | RST — Hardware reset input (active low) |
| Pin 34 | DAISYIN — Daisy-chain input from previous device |
| Pin 35 | CDOUT — Daisy-chain output to next device |
| Pin 36 | ALARM — Overrange / alarm digital output |
| Pin 37 | TRIG — External conversion trigger input |
| Pin 38 | DGND — Digital ground |
Aplicaciones típicas
ADS8688IDBTR es adecuado para 6 aplicacións: Industrial PLC Analog Input Modules, Multi-Axis Motor-Drive Feedback, Power-Metering Front-End, Multi-Channel Data-Acquisition Cards, Industrial Process-Control Transmitters, Battery Cell Monitoring & BMS Front-End.
Industrial PLC Analog Input Modules
The Texas Instruments ADS8688IDBTR is purpose-built for multi-channel PLC analog-input modules. Its 8-channel integrated MUX lets one IC service an entire 8-point analog input card with no external mux, saving roughly $3 in BOM versus a discrete MUX-plus-ADC architecture. The per-channel programmable ±10.24 V, ±5.12 V, and ±2.56 V bipolar ranges allow direct connection to standard 4-20 mA current-loop receivers via a 250 Ω sense resistor producing ±10 V full-scale signals - all from a single 5 V AVDD rail thanks to the integrated input attenuation and level-shift front-end. At 500 kSPS aggregate throughput (62.5 kSPS per channel at full multiplexing), the device comfortably handles typical PLC scan rates below 200 Hz with margin for oversampling. The ±20 V input clamp protects against field wiring transients and crossed wires common in plant retrofits. SPI daisy-chaining lets a single CS line service two ADS8688IDBTRs, expanding a single MCU peripheral to 16 channels without using additional GPIO - a key advantage when the host has limited SPI chip-select pins.
Recomendado
Multi-Axis Motor-Drive Feedback
Each axis of a 3-phase servo or stepper drive needs at least two analog feedback channels - phase current and DC-bus voltage - making a 3-axis drive a natural 6- or 8-channel data-acquisition problem. The ADS8688IDBTR's 8-channel integrated MUX lets one IC replace four discrete two-channel ADCs in a 3-axis servo controller, shrinking the analog front-end by half and freeing PCB area for power-stage layout. The 2 µs per-channel conversion time and zero conversion latency are critical for the deterministic current-loop control demanded by field-oriented control (FOC), which typically executes at 16 kHz to 32 kHz. The wide ±10.24 V bipolar input accepts scaled-down shunt-current-amplifier outputs directly, while the internal 4.096 V reference eliminates a discrete reference IC and its associated drift compensation. The 1.65 V to 5.25 V DVDD range lets the ADC connect directly to a 3.3 V Cortex-M4 MCU without level translation.
Recomendado
Power-Metering Front-End
Three-phase four-wire electricity meters simultaneously sense three phase voltages, three phase currents, and the neutral - a classic 7- or 8-channel measurement requirement. The ADS8688IDBTR's 8-channel MUX with auto-scan handles this with one chip, applying the per-channel input-range registers to scale CT (current transformer) and PT (potential transformer) outputs independently. The ±10.24 V range is compatible with shunts or CT burdens producing ±10 V outputs after signal conditioning. The 500 kSPS aggregate throughput enables simultaneous sampling class-0.5 metrology when combined with the device's zero-latency guarantee; the digital host can perform 32-cycle per-channel averaging to achieve the 1 kHz effective sample rate needed for 60 Hz fundamental and 50 harmonic components (per IEC 61000-4-7). The internal 4 ppm/°C reference removes the need for an external voltage reference or for routine periodic re-calibration across operating-temperature extremes of a meter installed in a service panel.
Recomendado
Multi-Channel Data-Acquisition Cards
PC-based DAQ cards for vibration monitoring, structural-health monitoring, or laboratory instrumentation routinely need 16 to 64 simultaneously sampled analog channels - which the ADS8688IDBTR can address efficiently using SPI daisy-chaining of up to four devices on a single bus, yielding 32 channels with one MCU peripheral. Each ADS8688IDBTR provides 8 channels at 500 kSPS aggregate and ±10 V input range, eliminating external input-protect circuits and signal-conditioning amplifiers. The integrated 4.096 V reference guarantees ±0.05% absolute accuracy at room temperature without a separate precision reference, lowering BOM and removing drift-sensitive components from the design. For applications requiring higher sampling rates on fewer channels, two ADS8688IDBTRs can be interleaved, with the MCU reading the channels in time-multiplexed fashion - delivering 1 MSPS effective per channel on 4 channels.
Recomendado
Industrial Process-Control Transmitters
Loop-powered 4-20 mA process transmitters typically sense one primary process variable (pH, conductivity, pressure, temperature) plus 2-3 secondary variables (ambient temperature, line voltage) that are calibrated or used for diagnostics. The ADS8688IDBTR integrates these into a single ADC IC, eliminating the second sensor-channel ADC and reducing standby current in the strict 4-20 mA loop budget of less than 3.6 mA total. The 16-bit resolution provides ample dynamic range for the primary variable across the entire 4-20 mA loop span, while the per-channel input ranges allow different transducers (pH probe, RTD bridge, current shunt) to be conditioned and digitized using a single ADC with software-scaling only - no analog gain switching. The wide -40 °C to +125 °C operating temperature range covers outdoor and process-field installations, and the integrated ±20 V overvoltage protection handles field surge events (per IEC 61000-4-5) without external protection that would load the 4-20 mA loop budget.
Recomendado
Battery Cell Monitoring & BMS Front-End
Lithium-ion battery management systems for energy storage and EV packs need precise cell-voltage measurement across many series-connected cells. The ADS8688IDBTR's 8-channel MUX lets a single ADC digitize an entire 8-cell module, while the ±10.24 V range covers the 0-5 V cell voltage plus headroom needed for pack-level diagnostics. Zero conversion latency lets the BMS controller trigger measurements synchronously with cell-balancing FET switching, avoiding the noise artifact that arises during FET transitions. The 5 V single analog supply matches the typical auxiliary rail in a battery pack, eliminating negative charge pumps required by bipolar-input ADCs that run off 3.3 V. When paired with a higher-count stack like a 96-cell battery, 12 ADS8688IDBTR devices can be daisy-chained (in groups of 4 per SPI bus using the device's CDOUT pin) to monitor 96 channels with only 3 GPIO lines from the BMS host MCU - a significant saving versus parallel-ADCs that require 96 chip-select lines or a large analog mux.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para ADS8688IDBTR — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | ADS8688IDBT | ADS8688IDBTR-Q1 | ADS8684IDBTR |
|---|---|---|---|---|
| Package | TSSOP-38 (DBT) | TSSOP-38 (DBT) - same | TSSOP-38 (DBT) - same | TSSOP-38 (DBT) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Resolution | 16 bits | 16 bits | 16 bits | 16 bits |
| Number of Channels | 8 channels | 8 channels | 8 channels | 4 channels |
| Sampling Rate | 500 kSPS | 500 kSPS | 500 kSPS | 500 kSPS |
| Bipolar Input Range | ±10.24 V | ±10.24 V | ±10.24 V | ±10.24 V |
| Automotive Qualified | No | No | Yes (AEC-Q100 Grade 1) | No |
| Daisy-Chain Capable | Yes (up to 4 devices) | Yes | Yes | Yes |
| Approx. Unit Price (qty 1000) | $9.85 | ~$9.00 (tray packing slight savings) | ~$13.50 (automotive grade premium) | ~$7.20 (4-channel version) |
Diferenciadores clave
- Integrated 8-input MUX with per-channel programmable ranges (frente a ADS8166 single-channel SAR ADC)
- True bipolar ±10.24 V input from a single 5 V analog supply (frente a External bipolar input ADC using negative charge pump)
- Automotive-grade variant available with identical die (frente a Generic industrial-grade 8-channel ADC from a third party)
Notas de diseño
Per the TI ADS8688 datasheet, the AVDD rail must be a low-noise 5 V supply capable of sourcing at least 25 mA per running ADS8688; use a ferrite bead from the system 5 V followed by a 10 µF X7R bulk plus 0.1 µF HF bypass within 5 mm of each AVDH/AVDD pin pair. DVDD can be supplied from 1.65 V to 5.25 V; provide a separate 0.1 µF ceramic near each DVDD pin. AVDD and DVDD grounds should be tied at a single-point star to avoid digital-return currents modulating the analog reference - this is the single largest contributor to spurious harmonics in SAR data converters.
Route analog input traces AINxP/AINxM as a 100 Ω differential pair from each channel to the ADC, kept short and isolated from digital traces (SDO, SCLK, SDI) by at least 0.5 mm. Place the 10 µF REFCAP capacitor within 2 mm of the REFCAP pin with a short trace to AGND - any series inductance at REFCAP directly degrades INL and adds channel-to-channel gain error. Confine the analog ground plane beneath the AIN signals and AGND pins only; cut the AGND plane away from the DGND-pin side of the package to break ground loops. A 4-layer PCB with a dedicated ground layer and a 5 V power layer is recommended.
Do not drive AINxP/AINxM with signals exceeding ±20 V or leave inputs floating while AVDD is on - the internal ±20 V clamps protect the device but sustained over-voltage dissipates thermal energy that can damage the package. Always toggle RST before the first conversion in SPI mode to ensure correct register initialization, particularly when the host MCU's POR tail is faster than the ADC's. When daisy-chaining, do not exceed 4 devices in one daisy-chain - cumulative SDO-to-SDI propagation delay degrades SPI timing margin. Estimated: at SCLK = 50 MHz with 4 daisy-chained parts, propagation delay through the CDOUT drivers adds approximately 32 ns (8 ns x 4 stages) to the readback, reducing setup time to ~8 ns.
Información de cumplimiento
Per TI product page: RoHS compliant, lead-free, halogen-free. The automotive-grade ADS8688IDBTR-Q1 variant is AEC-Q100 Grade 1 qualified (-40 °C to +125 °C) for automotive applications. The TSSOP-38 (DBT) package is Pb-free and JEDEC MSL-2 rated.
