Texas Instruments ADS7957SDBTR

Overview

ADS7957SDBTR from Texas Instruments is a 12-bit, 16-channel, single-ended SAR analog-to-digital converter with 1-MSPS sample rate, zero-latency operation, and 20-MHz SPI-compatible serial interface. It features two programmable alarm thresholds per channel, four configurable GPIOs (in TSSOP), and operates from 2.7–5.25 V analog supply and 1.7–5.25 V I/O supply. It is used in PLC analog input modules for real-time sensor monitoring.

For engineers reviewing the ADS7957SDBTR datasheet, ADS7957SDBTR pinout, ADS7957SDBTR application, or ADS7957SDBTR equivalent, key selection considerations include channel count (16), resolution (12-bit), unipolar input ranges (0 to VREF or 0 to 2×VREF), auto/manual channel sequencing, and GPIO alarm functionality in industrial data acquisition systems.

Technical Context

The ADS7957SDBTR implements a capacitor-based SAR architecture with integrated sample-and-hold, accepting analog inputs via a 16-channel single-ended multiplexer with MXO output. Conversion is triggered on the falling edge of CS, and serial data transfer uses SCLK-synchronized SDI/SDO with active-low CS control.

It supports dual software-selectable unipolar input ranges (0 to VREF and 0 to 2×VREF), auto-sequencing across preselected channels or manual channel selection per conversion cycle, and independent configuration of two alarm thresholds per channel. The device includes four GPIOs in the TSSOP package-GPIO0 (alarm), GPIO1 (low-alarm), GPIO2 (range select), and GPIO3 (power-down)-all programmable via SPI register writes.

Key Specifications

Pinout & Package

ADS7957SDBTR is packaged in a 38-pin TSSOP (DBT) with nominal body size 9.70 mm × 4.40 mm. All pins are electrically validated per TI SLAS605C Rev C (July 2018).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7957SDBTR, ADS7953SDBT simplifies supply design but sacrifices I/O voltage flexibility, while AD7949BCPZ-RL7 trades channel density and integrated alarms for increased resolution-making ADS7957SDBTR optimal for industrial systems needing 16-channel autonomy with minimal host overhead.

Availability

ADS7957SDBTR is available at Aetrix Electronics and suitable for PLC/IPC systems, optical line card monitoring, and medical instrumentation requiring stable component supply across extended production lifecycles.

Supply support for ADS7957SDBTR 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 company specializing in analog and embedded processing technologies, with leadership in precision data converters and industrial interface solutions.

The ADS79xx family was designed specifically for high-channel-count, real-time industrial data acquisition-emphasizing zero-latency conversion, integrated alarm logic, and flexible power domain separation to meet PLC, test equipment, and automation requirements.

FAQ

What is the maximum input frequency supported by ADS7957SDBTR before aliasing occurs?

The ADS7957SDBTR has a 47-MHz 3-dB input bandwidth and 1-MSPS sampling rate, meaning its Nyquist frequency is 500 kHz. To prevent aliasing, input signals must be band-limited to ≤500 kHz using an external anti-aliasing filter. The 47-MHz analog front-end ensures minimal attenuation and phase distortion up to that point, preserving signal integrity for accurate reconstruction. ADS7957SDBTR does not include an on-chip filter.

Does ADS7957SDBTR support differential input configurations?

ADS7957SDBTR accepts only single-ended analog inputs on CH0–CH15, with dedicated AINP/AINM pins supporting one differential auxiliary channel. It does not provide full differential input capability across all 16 channels. For true 16-channel differential acquisition, consider the ADS8688 or similar devices. ADS7957SDBTR's primary topology is single-ended multiplexed conversion with optional external PGA buffering via MXO.

How many GPIOs are available on ADS7957SDBTR and what are their default functions?

ADS7957SDBTR provides four GPIOs (GPIO0–GPIO3) in its 38-pin TSSOP package. By default: GPIO0 is configured as active-high alarm output, GPIO1 as active-high low-alarm output, GPIO2 as range-select input (high = 0 to 2×VREF), and GPIO3 as active-low power-down input. All GPIO functions are reprogrammable via SPI register writes per the ADS79xx programming model.

What reference voltage sources are compatible with ADS7957SDBTR?

ADS7957SDBTR accepts external reference voltages applied to REFP and REFM pins. TI's REF5025 (2.5-V, ±0.1% initial accuracy, 3-ppm/°C drift) is explicitly recommended in the datasheet. Other precision references meeting 2.5-V ±0.1-V tolerance, <10-μV p-p noise, and ≥10-mA output current capability (e.g., ADR4525) are also compatible. Internal reference is not provided - ADS7957SDBTR requires an external reference.

Can ADS7957SDBTR operate with different analog and I/O supply voltages simultaneously?

Yes. ADS7957SDBTR supports independent analog supply (+VA = 2.7–5.25 V) and digital I/O supply (+VBD = 1.7–5.25 V). This allows interfacing with 1.8-V FPGAs or 3.3-V microcontrollers while powering the analog core from a clean 5-V rail - reducing noise coupling and enabling mixed-voltage system designs. The ADS7957SDBTR datasheet specifies separate absolute maximum ratings and operating conditions for each domain.