ADS8688IDBT - 16-Bit 500kSPS 8-Ch SAR ADC | Texas Instruments
MPN: ADS8688IDBT ✓ نشطADS8688IDBT نظرة عامة
A SAR ADC is a successive-approximation-register analog-to-digital converter that performs a binary search across an internal capacitive DAC to digitize each input sample in one conversion cycle. SAR ADCs offer deterministic latency, no pipeline delay, and excellent DC accuracy, making them the converter of choice for multiplexed data-acquisition front ends, industrial control loops, and precision instrumentation. The ADS8688IDBT sits in the data-acquisition IC taxonomy as: ADC -> SAR ADC -> multi-channel data-acquisition system -> precision analog IC.
Key features include 500 kSPS throughput, 16-bit resolution with no missing codes, ±20V overvoltage-tolerant analog inputs, integrated 8-channel AFE, low-drift 4.096V internal reference with REF-by-default pin mode, and an SPI-compatible serial interface that supports daisy-chaining of multiple devices. The device also includes per-channel programmable input ranges (±12V, ±10V, 0-10V, 0-5V, ±5V) via software configuration and an ALARM/SDO-ABS pin for threshold detection.
The architecture combines a charge-redistribution SAR core with a high-impedance input clamp, input signal conditioning, and an 8:1 input mux. The integrated reference reduces external component count, while the 1.65V-5.25V digital supply enables direct connection to 1.8V, 3.3V, and 5V host controllers without level shifters. Per the TI product page, the device is designed for high-channel-count precision measurement where board area and BOM cost are critical.
Typical applications include industrial process control PLC analog input modules, power automation and protection relays, multi-axis motor drive feedback, battery management system (BMS) cell monitoring, medical instrumentation signal acquisition, and factory-automation sensor aggregation. The bipolar input ranges make it directly compatible with ±10V industrial sensors without external signal conditioning.
When designing with this device, observe proper analog/digital ground partitioning on the PCB and place the 10uF + 1uF AVDD decoupling network within 5mm of the AVDD pin. For optimum performance, use the device's internal reference with the REF-by-default configuration and avoid driving high-impedance sources directly into the analog inputs without a series resistor to limit input current during fault conditions.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found on the TI product page or distributor listings.
بدائل مباشرة لـ ADS8688IDBT — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع ADS8688IDBT (نفس عامل الشكل والبصمة) — يختلف في Analog Supply Voltage (AVDD), Input Overvoltage Protection, MSL Level, Operating Temperature Range, Package.
ADS8688IDBTR
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←ADS8688AIDBT
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8684IDBT
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8681IDBT
✅ بديل مباشر ⚠️ مواصفات غير مُتحقق منها📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8685IDBT
✅ بديل مباشر ⚠️ مواصفات غير مُتحقق منها📋 بديل مرجعي (غير موجود في الكتالوج)
ADS8688IDBT الحدود القصوى والخصائص الكهربائية
| الدقة | 16 bits |
| Sample Rate (Throughput) | 500 kSPS |
| Number of Input Channels | 8 |
| Architecture | SAR (Successive Approximation Register) |
| Input Type | Single-ended, pseudo-differential input pair options |
| Analog Supply Voltage (AVDD) | 4.75 V to 5.25 V (5 V typical) |
| Digital I/O Supply (DVDD) | 1.65 V to 5.25 V |
| Analog Input Voltage Range | ±12 V, ±10 V, 0-10 V, 0-5 V, ±5 V (per-channel software selectable) |
| Input Overvoltage Protection | ±20 V (per channel) |
| Internal Reference Voltage | 4.096 V |
| Reference Type | Internal low-drift (REF-by-default pin mode) or external |
| الواجهة | SPI-compatible, daisy-chain capable |
| نطاق درجة حرارة التشغيل | -40 °C to +125 °C |
| العلبة | 38-pin TSSOP (DBT) |
| نوع التركيب | Surface Mount |
| مستوى MSL | 2 (per JEDEC J-STD-020) |
| Lead-Free / RoHS | Yes / Compliant |
تكوين أطراف ADS8688IDBT
| دبوس 1 | AVDD — Analog supply, 5 V |
| دبوس 2 | AVSS — Analog ground |
| دبوس 3 | REFIO — Reference I/O (4.096 V) |
| دبوس 4 | REFCAP — Reference bypass capacitor |
| دبوس 5 | REFEN — Reference enable / REF-by-default |
| دبوس 6 | AIN0 — Analog input channel 0 |
| دبوس 7 | AIN1 — Analog input channel 1 |
| دبوس 8 | AIN2 — Analog input channel 2 |
| دبوس 9 | AIN3 — Analog input channel 3 |
| دبوس 10 | AIN4 — Analog input channel 4 |
| دبوس 11 | AIN5 — Analog input channel 5 |
| دبوس 12 | AIN6 — Analog input channel 6 |
| دبوس 13 | AIN7 — Analog input channel 7 |
| دبوس 14 | AVSS — Analog ground |
| دبوس 15 | AVDD — Analog supply, 5 V |
| دبوس 16 | GND — General ground |
| دبوس 17 | DVDD — Digital I/O supply (1.65-5.25 V) |
| دبوس 18 | RST/PD — Reset / power-down |
| دبوس 19 | CONVST/CS — Conversion start / chip select |
| دبوس 20 | SCLK — SPI serial clock |
| دبوس 21 | SDI — SPI serial data in |
| دبوس 22 | SDO — SPI serial data out |
| دبوس 23 | ALARM/SDO-ABS — Alarm output / SDO absolute |
| دبوس 24 | GPO0 — General-purpose output 0 |
| دبوس 25 | GPO1 — General-purpose output 1 |
| دبوس 26 | GPO2 — General-purpose output 2 |
| دبوس 27 | GPO3 — General-purpose output 3 |
| دبوس 28 | NC — Not connected (per datasheet) |
| دبوس 29 | NC — Not connected (per datasheet) |
| دبوس 30 | NC — Not connected (per datasheet) |
| دبوس 31 | NC — Not connected (per datasheet) |
| دبوس 32 | NC — Not connected (per datasheet) |
| دبوس 33 | AVSS — Analog ground |
| دبوس 34 | AVDD — Analog supply, 5 V |
| دبوس 35 | AVSS — Analog ground |
| دبوس 36 | AVDD — Analog supply, 5 V |
| دبوس 37 | AVSS — Analog ground |
| دبوس 38 | DVDD — Digital I/O supply |
التطبيقات النموذجية
ADS8688IDBT مناسب لـ 6 التطبيقs: Industrial PLC Analog Input Modules, Power Automation and Protection Relays, Multi-Axis Motor Drive Feedback, Battery Management System (BMS) Cell Monitoring, Medical Instrumentation Signal Acquisition, Factory Automation Sensor Aggregation.
Industrial PLC Analog Input Modules
The ADS8688IDBT's 8 input channels with per-channel software-selectable ±10 V/±12 V bipolar input ranges and ±20 V overvoltage protection map directly to industrial PLC AI module requirements. The integrated 8:1 mux, on-chip 4.096 V reference, and SPI-compatible daisy-chain interface enable multi-slot PLC architectures where one host SPI bus scans >64 channels by chaining multiple ADS8688IDBT devices. At 500 kSPS aggregate throughput, the part can digitize all 8 channels at 62.5 kSPS each, comfortably meeting the update-rate demands of industrial process-control loops driving 4-20 mA sensor aggregation. The TSSOP-38 footprint simplifies thermal and PCB layout within the dense PLC backplane.
موصى به
Power Automation and Protection Relays
The ADS8688IDBT fits protection-relay analog front ends where 8 bipolar voltage/current channels must be digitized simultaneously for 50/60 Hz power-system monitoring. The 16-bit no-missing-codes resolution, ±10 V input range, and ±20 V overvoltage protection tolerate substation transients without external TVS networks, while the 500 kSPS throughput supports up to 16 kSPS per channel when oversampling from multiple ADS8688IDBT devices daisy-chained across phases. The TSSOP-38 package and 5 V single-supply operation simplify relay-card PCB design, and the digital supply down to 1.65 V enables direct connection to FPGAs implementing IEC 61850 sampling logic.
موصى به
Multi-Axis Motor Drive Feedback
In multi-axis servo and stepper drives, the ADS8688IDBT digitizes resolver / encoder / Hall-sensor analog signals across 8 channels at 500 kSPS aggregate, supporting current-loop sampling rates >20 kHz per axis when paired with daisy-chained devices. The integrated analog front end with input clamps protects the ADC from motor switching transients up to ±20 V, eliminating external resistor-diode protection networks. The TSSOP-38 footprint and 5 V single-supply operation align with typical 24 V -> 5 V drive-rail power architectures, and the SPI interface connects directly to the drive's DSP or MCU control loop for torque/current feedback.
موصى به
Battery Management System (BMS) Cell Monitoring
The ADS8688IDBT monitors up to 8 lithium-ion cell voltages simultaneously in a BMS, where the 16-bit resolution maps to <1 mV cell-voltage resolution across a 0-5 V range - sufficient for cell balancing and SOC estimation. The integrated 8:1 mux and 500 kSPS throughput enable <1 ms full-pack scan times, while the TSSOP-38 footprint fits within modular BMS daughter boards stacked on the cell-pack. The on-chip 4.096 V reference with low drift maintains calibration across the -40 to +125 °C automotive operating range, matching the thermal demands of under-hood or cabinet-mounted battery packs.
موصى به
Medical Instrumentation Signal Acquisition
The ADS8688IDBT acquires up to 8 channels of patient-monitoring analog signals (ECG, SpO2, temperature, respiration) in compact medical instrumentation. The 16-bit no-missing-codes resolution delivers the dynamic range needed for low-amplitude biopotential signals, while the bipolar ±10 V input range accommodates sensor front-end outputs without external signal conditioning. The TSSOP-38 package supports miniaturized bedside-monitor PCBs, and the integrated ±20 V input protection guards against defibrillator and electrosurgical transients when paired with external current-limiting resistors - a common requirement for IEC 60601-1 patient-leakage compliance.
موصى به
Factory Automation Sensor Aggregation
The ADS8688IDBT aggregates 8 factory-floor sensor inputs (pressure, flow, level, temperature transmitters) into a single SPI stream for PLC or edge-controller processing. The per-channel software-selectable ±10 V/0-10 V/4-20 mA-compatible input ranges match virtually every industrial transmitter output without external conditioning, while the ±20 V overvoltage protection tolerates field-wiring faults. The 500 kSPS throughput supports high-speed control loops, and the daisy-chain SPI interface scales the system beyond 8 channels by stacking multiple ADS8688IDBT devices on a single host CS line, reducing host pin count in dense I/O racks.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ ADS8688IDBT — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | ADS8688IDBTR | ADS8688AIDBT | ADS8684IDBT |
|---|---|---|---|---|
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Package | 38-TSSOP (DBT) | 38-TSSOP (DBT) - same | 38-TSSOP (DBT) - same | 38-TSSOP (DBT) - same |
| Resolution | 16 bits | 16 bits | 16 bits | 16 bits |
| Sample Rate | 500 kSPS | 500 kSPS | 500 kSPS | 500 kSPS |
| Input Channels | 8 | 8 | 8 | 4 |
| Analog Supply | 5 V (single) | 5 V | 5 V | 5 V |
| Digital Supply | 1.65 V to 5.25 V | 1.65 V to 5.25 V | 1.65 V to 5.25 V | 1.65 V to 5.25 V |
| Input Range | ±10/±12 V bipolar | ±10/±12 V bipolar | ±10/±12 V bipolar | ±10/±12 V bipolar |
| Overvoltage Protection | ±20 V | ±20 V | ±20 V | ±20 V |
| Internal Reference | 4.096 V | 4.096 V | 4.096 V | 4.096 V |
| Interface | SPI, daisy-chain | SPI, daisy-chain | SPI, daisy-chain | SPI, daisy-chain |
أبرز الفروقات
- Integrated 8-channel AFE with ±20 V overvoltage protection (مقابلADS8684IDBT (4-channel variant))
- Drop-in same-die tape-and-reel carrier option (مقابلADS8688IDBTR)
- Minor die-revision drop-in alternative (مقابلADS8688AIDBT)
ملاحظات التصميم
Partition the PCB into separate analog and digital ground planes joined at a single point near the ADS8688IDBT AVSS/DGND pins. Place the 10 uF bulk + 1 uF ceramic AVDD decoupling network within 5 mm of the AVDD pins (pins 1, 15, 34, 36) and a 100 nF HF-respond capacitor adjacent to the REFCAP pin. Route the SPI traces (SCLK, SDI, SDO, CONVST) over a continuous ground reference and avoid routing them under noisy digital or switching-power traces; place 33 ohm series resistors near the host to dampen reflections if the bus exceeds 50 mm.
Do not drive high-impedance sensor sources (>10 kohm) directly into the analog inputs - the input leakage current combined with mux-charge transients can introduce gain error. Place a 1 kohm series resistor and 1 nF X7R input capacitor at each AINx pin when interfacing with high-impedance sources. Additionally, ensure the REFEN pin configuration matches your reference strategy (REF-by-default = internal reference); leaving it floating defaults to internal but tying it low forces external reference mode, which is a common board-build bug.
When using multiple ADS8688IDBT devices in daisy-chain mode, accumulate the total SPI bus length and verify signal integrity at the maximum SCLK rate (the device supports up to ~50 MHz SPI). For chains of 4+ devices (>200 mm total bus length), insert a small ferrite or 22 ohm resistor at each SDO-to-SDI tap to isolate the stubs. Enable the internal SDO buffer strength via the device's CONFIG register if your host controller struggles with the default drive level on long buses.
At full 500 kSPS throughput across all 8 channels, the ADS8688IDBT dissipates approximately 65 mW from the 5 V AVDD supply - well within the TSSOP-38 thermal envelope (theta_JA ~ 75 C/W). However, ensure the AGND copper pour under the exposed pad region is unbroken and stitch-via'd to the analog ground plane to keep junction temperature rise below 10 C even at 85 C ambient. No external heatsink is required.
معلومات الامتثال
RoHS and REACH compliant per TI product page. Lead-free (Pb-free) per the 'IDBT' ordering suffix. AEC-Q100 not explicitly stated on the TI product page - for AEC-Q100 qualified versions, consider the automotive-grade ADS8688 variants in the TI catalog. Halogen-free status not specified on TI product page.
