Texas Instruments ADS8688IDBT

Overview

ADS8688IDBT from Texas Instruments is a 16-bit, 8-channel, single-supply SAR analog-to-digital converter with integrated analog front-end, ±10.24 V bipolar input range support, 500-kSPS aggregate throughput, and on-chip 4.096-V reference. It delivers ±0.75 LSB INL, 92 dB SNR, and operates across –40°C to 125°C for industrial data acquisition systems.

For engineers reviewing the ADS8688IDBT datasheet, ADS8688IDBT pinout, ADS8688IDBT application, or ADS8688IDBT equivalent, this page provides verified technical context, channel-independent programmable input ranges (±10.24 V / ±5.12 V / ±2.56 V), 1-MΩ constant input impedance, and SPI-compatible daisy-chain interface details essential for PLC analog input module design.

Technical Context

The ADS8688IDBT integrates an 8-channel multiplexer with per-channel programmable gain amplifier (PGA), second-order LPF, overvoltage protection (±20 V), and a precision 4.096-V internal reference. Each channel supports independent software-selectable bipolar (±10.24 V, ±5.12 V, ±2.56 V) or unipolar (0–10.24 V, 0–5.12 V) input ranges.

It uses successive approximation register (SAR) architecture with 850 ns conversion time and 1150 ns acquisition time, enabling full 500-kSPS aggregate sampling without latency. The digital interface is SPI-compatible with CS, SCLK, SDI, SDO, and DAISY pins supporting multi-device daisy-chaining and 1.65–5.25-V I/O voltage flexibility.

Key Specifications

Pinout & Package

TSSOP-38 package (9.7 mm × 4.4 mm) with exposed thermal pad; pin-compatible with ADS8684IDBT but with additional AIN_4P/GND through AIN_7P/GND connections.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit multichannel SAR ADC applications.

Compared with ADS8684IDBT, the ADS8688IDBT adds four extra analog input channels while retaining identical timing, accuracy, and thermal specs; versus AD7606C-16BSTZ, it integrates the reference and reduces digital interface complexity at lower power consumption.

Availability

ADS8688IDBT is available at Aetrix Electronics and suitable for power automation, protection relays, and PLC analog input modules requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceable sourcing.

Supply support for ADS8688IDBT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision data converters for industrial applications.

The ADS868x family-including ADS8688IDBT-is designed specifically for ruggedized industrial data acquisition, integrating front-end protection, programmable ranges, and robust serial interfacing to simplify high-channel-count analog input system design.

FAQ

What input voltage ranges does the ADS8688IDBT support?

The ADS8688IDBT supports channel-independent software-selectable input ranges: bipolar ±10.24 V, ±5.12 V, ±2.56 V and unipolar 0–10.24 V, 0–5.12 V. These ranges are enabled by its integrated PGA and referenced to the internal 4.096-V reference. All ranges maintain 1-MΩ input impedance and ±20 V overvoltage protection, making ADS8688IDBT suitable for direct interfacing with industrial sensors and isolation amplifiers without external signal conditioning.

Does the ADS8688IDBT require an external reference voltage?

No, the ADS8688IDBT includes a factory-trimmed, low-drift 4.096-V internal reference with ±10 ppm/°C temperature coefficient. When REFSEL is pulled low, REFIO outputs this reference; when high, REFIO accepts an external 4.046–4.146 V source. The internal reference eliminates BOM cost and layout complexity, and ADS8688IDBT's performance specifications-including 92 dB SNR and ±0.75 LSB INL-are guaranteed with the internal reference enabled.

How many analog input channels does the ADS8688IDBT have, and what is their configuration?

The ADS8688IDBT features eight single-ended analog input channels (AIN_0P through AIN_7P), each with dedicated negative input (AIN_0GND through AIN_7GND) for pseudo-differential operation. It also includes a dedicated auxiliary channel (AUX_IN/AUX_GND). All nine inputs are independently configurable for bipolar or unipolar ranges. Unlike multiplexed single-input ADCs, ADS8688IDBT's per-channel PGA and front-end allow true independent range selection-enabling mixed-signal acquisition (e.g., ±10 V voltage + 4–20 mA current on same device).

What is the maximum sampling throughput of the ADS8688IDBT?

The ADS8688IDBT achieves a guaranteed 500-kSPS aggregate throughput across all eight channels, meaning it can sample each channel at up to 62.5 kSPS in round-robin mode. Its 850 ns conversion time and 1150 ns acquisition time enable this rate without pipeline latency. This throughput is maintained across the full –40°C to 125°C temperature range and with either internal or external reference, making ADS8688IDBT appropriate for real-time control loops and power quality monitoring where deterministic timing is essential.

Is the ADS8688IDBT compatible with daisy-chained SPI configurations?

Yes, the ADS8688IDBT supports daisy-chained SPI operation using the DAISY pin. In daisy-chain mode, multiple ADS8688IDBT devices share a single CS and SCLK line, with SDO of one device connected to SDI of the next. Data is shifted out sequentially, allowing up to 16 devices on one bus. This reduces host controller pin count and simplifies modular analog input expansion-critical for scalable PLC backplanes and distributed I/O systems where ADS8688IDBT serves as the core acquisition node.