Texas Instruments ADS8321E/250G4

Overview

ADS8321E/250G4 from Texas Instruments is a 16-bit SAR analog-to-digital converter with differential bipolar input, 100kHz sampling rate, ±0.018% integral linearity error, and MSOP-8 package. It operates from 4.75V to 5.25V, consumes only 4.5mW at full rate, and supports SPI/SSI-compatible serial interface for microcontroller integration in portable data acquisition.

For engineers reviewing the ADS8321E/250G4 datasheet, ADS8321E/250G4 pinout, ADS8321E/250G4 application, or ADS8321E/250G4 equivalent, key selection considerations include its 16-bit resolution with tested INL over –40°C to +85°C, differential input range up to ±VREF, reference voltage flexibility (0.5V to VCC/2), and power-down current of ≤3µA - critical for battery-powered remote sensing and isolated DAQ systems.

Technical Context

The ADS8321E/250G4 implements a capacitive redistribution SAR architecture fabricated in 0.6µm CMOS, enabling single-cycle 16-bit conversion in 16 clock cycles with no pipeline delay. Its analog front-end features matched differential inputs (+In/–In) and internal sample/hold, supporting both single-ended and fully differential signal acquisition.

Digital interface uses synchronous 3-wire SPI/SSI protocol: CS/SHDN initiates conversion and controls shutdown mode; DCLOCK synchronizes bit transfer on falling edge; DOUT outputs 16-bit two's complement data MSB-first. Reference input impedance exceeds 5GΩ, and input capacitance is 25pF with 4.5 clock-cycle acquisition time.

Key Specifications

Pinout & Package

ADS8321E/250G4 is housed in an MSOP-8 (DGK) package - 3.0mm × 3.0mm, 0.65mm pitch, exposed pad optional - optimized for space-constrained PCB layouts in portable instrumentation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7816U and ADS8322E/250, the ADS8321E/250G4 uniquely balances ultra-low power (4.5mW), differential input capability, and cost-effective MSOP-8 packaging - making it optimal for battery-operated DAQ where precision and noise rejection are prioritized over maximum speed or ultimate linearity.

Availability

ADS8321E/250G4 is available at Aetrix Electronics and suitable for battery-powered data loggers, isolated industrial sensors, remote vibration monitoring nodes, and multi-channel simultaneous sampling systems requiring stable component supply across extended production lifecycles.

Supply support for ADS8321E/250G4 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 and low-power signal chains.

The ADS8321E/250G4 belongs to TI's precision SAR ADC product line, engineered specifically for portable, isolated, and multi-channel data acquisition where microamp-level shutdown current and differential input integrity are mandatory design requirements.

FAQ

What is the maximum sampling rate supported by the ADS8321E/250G4?

The ADS8321E/250G4 supports a maximum sampling rate of 100kHz under specified conditions (VCC = 5V, fCLK = 2.4MHz). This rate is achievable with 16 clock cycles per conversion and requires the external clock to operate within 24kHz–2.4MHz. At lower rates such as 10kHz, average power drops to <1mW, enabling extended battery operation. The device maintains tested specifications across –40°C to +85°C at this rate.

Does the ADS8321E/250G4 require an external reference voltage?

Yes, the ADS8321E/250G4 requires an external reference voltage applied to the VREF pin. It accepts any stable voltage from 0.5V to VCC/2 (e.g., 2.5V at VCC = 5V), which directly defines the full-scale differential input range (±VREF). Reference current ranges from 0.1µA to 80µA depending on sample rate and CS state. A clean, low-noise reference - such as buffered OPA627 output - is recommended to preserve 16-bit ENOB.

How does the power-down mode function on the ADS8321E/250G4?

The ADS8321E/250G4 enters full power-down mode when CS/SHDN is driven HIGH, reducing supply current to ≤3µA. In this state, both analog and digital sections are disabled. When CS is LOW but no conversion is active, only the analog section shuts down; digital logic remains active, consuming more current. For minimum power, assert CS HIGH between conversions - especially critical in battery-powered ADS8321E/250G4 deployments where duty cycling extends operational lifetime.

Is the ADS8321E/250G4 pin-compatible with other TI ADCs?

Yes, the ADS8321E/250G4 is pin-compatible with the ADS7816 and ADS7822 in the same MSOP-8 (DGK) package. This allows direct substitution in existing designs without PCB changes, though functional differences exist: ADS7816 is single-ended only, while ADS7822 offers 12-bit resolution. Engineers should verify reference configuration, input drive strength, and timing margins before drop-in replacement of ADS8321E/250G4.

What digital interface protocol does the ADS8321E/250G4 use?

The ADS8321E/250G4 uses a synchronous 3-wire serial interface compatible with SPI and SSI standards. Communication requires CS/SHDN (active-low chip select), DCLOCK (data synchronization), and DOUT (serial data output). Data is transmitted MSB-first on the falling edge of DCLOCK, with one null bit preceding the 16-bit two's complement result. No external frame sync or MOSI line is needed, simplifying microcontroller integration in ADS8321E/250G4-based systems.