Texas Instruments ADS7891IPFBR

Overview

ADS7891IPFBR from Texas Instruments is a 14-bit, 3-MSPS successive approximation register (SAR) analog-to-digital converter with integrated 2.5-V reference, pseudo-differential input (−0.2 V to +0.2 V on −IN), zero-latency operation, and high-speed parallel interface. It delivers 78 dB SNR and 88.5 dB THD at full throughput and supports nap mode (2–3 mA) for dynamic power scaling in high-speed data acquisition systems.

For engineers reviewing the ADS7891IPFBR datasheet, ADS7891IPFBR pinout, ADS7891IPFBR application, or ADS7891IPFBR equivalent, this page provides verified technical context, package-validated pin functions, real-world timing constraints (e.g., 273 ns max conversion time, 25 ns quiet sampling), and selection guidance for optical networking, spectrum analysis, and closed-loop control systems requiring deterministic latency and ≥14-bit linearity.

Technical Context

The ADS7891IPFBR implements a capacitor-based SAR architecture with inherent sample-and-hold, internal clock generation, and straight-binary 14-bit output. Its pseudo-differential input stage accepts 0 V to 2.5 V unipolar spans while rejecting common-mode noise via ±200 mV −IN swing - critical for sensor-ground mismatch compensation in precision signal chains.

It supports three operational modes: full-rate (3 MSPS), nap mode (2–3 mA supply current, 60 ns extended acquisition), and power-down (2.5 µA). Control is managed via dedicated pins: CONVST (edge-triggered acquisition/conversion), BUSY (status), BYTE (8/14-bit bus select), A_PWD (nap enable), and PWD/RST (asynchronous reset/power-down).

Key Specifications

Pinout & Package

ADS7891IPFBR is housed in a 48-pin TQFP (PFB) package with exposed thermal pad, optimized for analog/digital ground separation and low-inductance decoupling. Pin assignments follow TI's standard layout for high-speed ADCs, with dedicated AGND/+VA, BDGND/+VBD, and REFM planes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed SAR ADC applications.

Compared with ADS7891IPFBR, ADS8325IPFBR trades 2 MSPS throughput and parallel interface for 2 extra bits and SPI simplicity, while ADS7854IPFBR matches speed and packaging but omits nap mode - making ADS7891IPFBR uniquely suited for battery-aware, high-throughput embedded systems.

Availability

ADS7891IPFBR is available at Aetrix Electronics and suitable for optical networking, spectrum analysis, and high-speed closed-loop control systems requiring stable component supply, long-term industrial temperature support (−40°C to +85°C), and guaranteed 14-bit monotonicity.

Supply support for ADS7891IPFBR 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 high-performance data converters and precision signal chain solutions.

The ADS7891IPFBR belongs to TI's high-speed SAR ADC family designed for applications demanding zero-latency, deterministic timing, and integrated reference stability - particularly in test equipment, medical imaging, and optical infrastructure.

FAQ

What is the maximum sample rate and resolution of the ADS7891IPFBR?

The ADS7891IPFBR achieves a maximum sample rate of 3 MSPS at full 14-bit resolution with no missing codes across its operating temperature range. Its SAR architecture guarantees monotonicity and zero latency - meaning the digital output corresponds precisely to the analog input sampled at the falling edge of the CONVST signal. This makes ADS7891IPFBR suitable for real-time control loops where timing determinism is critical.

Does the ADS7891IPFBR include an internal voltage reference?

Yes, the ADS7891IPFBR integrates a buffered 2.5 V nominal internal reference with ±0.02 V initial accuracy and 25 ppm/°C temperature drift. When enabled, REFOUT (Pin 2) must be connected to REFIN (Pin 1) with proper decoupling (0.1 µF + 1 µF to REFM). This eliminates external reference components and layout sensitivity, simplifying design for applications like portable spectrum analyzers and ultrasound front-ends where board space and thermal stability matter.

How does the nap mode function on the ADS7891IPFBR?

Nap mode on the ADS7891IPFBR is activated by pulling A_PWD (Pin 37) low, reducing supply current from 17–18 mA to 2–3 mA between conversions. It maintains full 14-bit accuracy but extends acquisition time by 60 ns. This mode is ideal for burst-sampling applications such as optical switch calibration or transient capture in ATE, where high throughput is needed only intermittently - delivering >90% average power reduction without sacrificing fidelity or requiring firmware changes.

What are the key timing constraints for reliable data capture with the ADS7891IPFBR?

Reliable data capture with the ADS7891IPFBR requires adherence to strict timing windows: CONVST pulse width ≥70 ns, CS/ RD setup/hold times ≥10 ns, and a mandatory 25 ns quiet period before CONVST falling edge. Conversion time is ≤273 ns (at +VBD = 5 V), and BUSY remains high throughout. Violating these - especially the quiet sampling window - introduces aperture jitter and degrades SNR/THD. These values are measured under 20 pF load and are validated across −40°C to +85°C.

Can the ADS7891IPFBR interface directly with an 8-bit microcontroller?

Yes, the ADS7891IPFBR supports byte-mode operation via the BYTE pin (Pin 39). When BYTE = high, the lower 6 bits (D5–D0) are mapped to DB13–DB8, allowing two sequential 8-bit reads to reconstruct the full 14-bit word. This eliminates level shifters or bus transceivers when interfacing with legacy 8-bit MCUs like the PIC18F or 8051 derivatives - a feature confirmed in TI's SLAS410 datasheet and validated in reference designs for portable instrumentation.