Texas Instruments ADS7890IPFBR

Overview

ADS7890IPFBR from Texas Instruments is a 14-bit, 1.25 MSPS successive approximation register (SAR) analog-to-digital converter with internal 2.5-V reference, pseudo-differential input (0 V to 2.5 V span), SPI/DSP-compatible serial interface, and zero-latency operation. It delivers 77.5 dB SNR and −95 dB THD at 0.5 MHz input frequency, and supports Nap mode (10 mW) and full power-down (2.5 µA) for dynamic power management in high-speed data acquisition systems.

For engineers reviewing the ADS7890IPFBR datasheet, ADS7890IPFBR pinout, ADS7890IPFBR application, or ADS7890IPFBR equivalent, this page provides verified technical context, real-world timing behavior, validated pin functions, confirmed analog input constraints (±200 mV on −IN), and precise alternative selection guidance for optical networking, spectrum analysis, and closed-loop control designs.

Technical Context

The ADS7890IPFBR implements a capacitor-based SAR architecture with inherent sample-and-hold, enabling true zero-latency conversion. Its pseudo-differential input stage accepts +IN (−0.2 V to 2.7 V) and −IN (−0.2 V to +0.2 V), allowing ±200 mV common-mode swing to reject ground mismatch and noise-critical for sensor interfacing in noisy industrial environments.

It supports dual digital interfaces: SPI (CS/SCLK only, FS held high) and DSP (CS/SCLK/FS), both delivering 14-bit straight-binary output with MSB-first timing. Conversion is initiated by CS falling edge (SPI) or FS rising edge (DSP), with BUSY asserted for 365 ns; internal clock generation eliminates external timing dependencies.

Key Specifications

Pinout & Package

ADS7890IPFBR is housed in a 48-pin TQFP (PFB) package with exposed thermal pad, optimized for analog signal integrity via dedicated AGND/+VA and BDGND/+VBD power domains. Pin assignments follow TI's standard layout for high-speed ADCs, with analog and digital grounds isolated and decoupled per design guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8325IPFB and AD7890-10BRZ, the ADS7890IPFBR uniquely combines 14-bit speed, internal reference, Nap mode, and pseudo-differential input in a 48-pin TQFP-making it optimal for space-constrained, noise-sensitive, high-throughput systems where reference integration and power adaptability are critical.

Availability

ADS7890IPFBR is available at Aetrix Electronics and suitable for optical networking infrastructure, spectrum analysis instrumentation, and high-speed closed-loop control systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for ADS7890IPFBR 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 high-reliability industrial ICs.

The ADS7890IPFBR belongs to TI's high-speed SAR ADC product line, engineered for applications demanding fast, accurate digitization with minimal system-level overhead-particularly in telecom, test equipment, and real-time control.

FAQ

What is the absolute input voltage limit for −IN on the ADS7890IPFBR?

The ADS7890IPFBR specifies an absolute −IN voltage range of −0.2 V to +0.2 V. Exceeding this violates the pseudo-differential architecture and risks linearity degradation or damage. This constraint enables common-mode rejection while maintaining internal CDAC stability. The +IN input spans −0.2 V to (VREF + 0.2 V), with full-scale defined as (+IN − −IN) = 0 V to 2.5 V. Always verify source impedance matching between +IN and −IN to avoid gain/offset errors.

Does the ADS7890IPFBR require an external reference, or can it operate with its internal reference?

The ADS7890IPFBR operates with its internal 2.5-V reference by default and does not require an external reference. When using the internal reference, REFOUT (Pin 2) must be connected to REFIN (Pin 1) with a 0.1-µF ceramic bypass capacitor and a 1-µF storage capacitor to REFM (Pins 47/48). External references are supported but necessitate disconnecting REFOUT from REFIN and decoupling REFIN to AGND with 0.1 µF-adding complexity the ADS7890IPFBR avoids in most implementations.

How does the Nap mode function in the ADS7890IPFBR, and what is its power impact?

The ADS7890IPFBR enters Nap mode automatically after conversion completion and remains there until the 8th SCLK rising edge. In Nap mode, analog circuitry remains biased but digital logic idles, reducing power dissipation from 45 mW to 10 mW at 1.25 MSPS. This state is distinct from full power-down (2.5 µA), which requires a sustained low pulse on PWD/RST. Nap mode enables rapid wake-up (<25 ms REFOUT startup) and preserves reference stability-ideal for burst-mode acquisition in ADS7890IPFBR-based systems.

What are the timing-critical pins for achieving specified SNR and THD in the ADS7890IPFBR?

To achieve the datasheet's 77.5 dB SNR and −95 dB THD, SCLK jitter must be minimized-TI explicitly states that SCLK jitter directly degrades SNR performance. BUSY (365 ns pulse width) and SDO (9 ns delay from SCLK rising edge) also demand tight board-level timing control. Layout best practices include short, matched SCLK/SDO traces, separate AGND/BGDGND planes tied under the device, and strict decoupling of +VA, +VBD, and REFOUT. Failure to manage SCLK edge integrity will measurably reduce ADS7890IPFBR dynamic performance.

Can the ADS7890IPFBR interface with a 3.3-V microcontroller without level shifters?

Yes-the ADS7890IPFBR supports +VBD from 2.7 V to 5.25 V, making direct 3.3-V logic interfacing fully compatible. VIH is defined as +VBD − 1 V (min 2.3 V at 3.3 V), and VOL is 0.4 V max-well within standard 3.3-V CMOS thresholds. SDO output drives 2 TTL loads, and BUSY/CS/FS/SCLK inputs meet 3.3-V logic levels without translation. However, +VA must remain at 5 V (4.75–5.25 V) for analog performance compliance; mixing 3.3-V digital and 5-V analog supplies is standard practice for ADS7890IPFBR designs.