Texas Instruments ADS7891IPFBT

Overview

ADS7891IPFBT 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 V to 2.5 V full-scale), zero-latency operation, and high-speed parallel interface. It delivers 78 dB SNR and 88.5 dB THD at 3 MSPS and supports nap mode (10 mW) for dynamic power scaling in high-speed data acquisition systems.

For engineers reviewing the ADS7891IPFBT datasheet, ADS7891IPFBT pinout, ADS7891IPFBT application, or ADS7891IPFBT equivalent, this page provides verified technical context, validated pin functions, real-world use cases in optical networking and spectrum analysis, and confirmed alternative options for system-level design continuity.

Technical Context

The ADS7891IPFBT implements a capacitor-based SAR architecture with inherent sample-and-hold, internal conversion clock generation (max 273 ns conversion time), and pseudo-differential input stage where −IN accepts ±200 mV to reject ground mismatch and common-mode noise. Its 14-bit parallel bus supports byte-mode folding for 8-bit microprocessor interfacing.

Control logic enables three sampling start methods (CONVST rise, CS fall with CONVST high, or internal back-to-back trigger), supports conversion abort (outputs 0x3F80), and integrates dedicated nap (A_PWD) and power-down/reset (PWD/RST) inputs with defined wake-up timing (25 ms power-up after reset, 60 ns added acquisition post-nap).

Key Specifications

Pinout & Package

ADS7891IPFBT is housed in a 48-pin TQFP package (PFB designation), with exposed thermal pad, 0.5 mm pitch, and RoHS-compliant finish. Analog and digital grounds are segregated (AGND ×8, BDGND ×2), and power supplies are split (+VA ×5, +VBD ×2) to minimize coupling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8325IPFBT and AD9240ASTZ, the ADS7891IPFBT uniquely balances 3 MSPS throughput, zero-latency parallel output, integrated reference, and 10 mW nap mode - making it optimal for space-constrained, real-time embedded acquisition where latency and power co-constrain design.

Availability

ADS7891IPFBT is available at Aetrix Electronics and suitable for optical networking equipment, spectrum analyzer front-ends, and portable ultrasound systems requiring stable component supply across extended product lifecycles.

Supply support for ADS7891IPFBT 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-speed interface solutions.

The ADS7891IPFBT belongs to TI's high-speed SAR ADC product line, engineered specifically for applications demanding zero-latency digitization, low-power operational flexibility, and robust noise immunity in instrumentation and communications infrastructure.

FAQ

What is the maximum sample rate and effective number of bits (ENOB) of the ADS7891IPFBT?

The ADS7891IPFBT achieves a maximum sample rate of 3 MSPS with 13.0 ENOB at 100 kHz input frequency and 12.5 ENOB at 1 MHz, as measured under standard conditions (+VA = 5 V, Vref = 2.5 V, TA = 25°C). Its 78 dB SNR and −88.5 dB THD directly determine ENOB, and performance remains stable across −40°C to +85°C per Figure 14 in the SLAS410 datasheet. The ADS7891IPFBT maintains monotonicity with no missing codes at full 14-bit resolution.

Does the ADS7891IPFBT require an external reference, or can it operate with its internal reference?

The ADS7891IPFBT can operate with either its internal 2.5-V reference or an external reference. When using the internal reference, pins REFIN (1) and REFOUT (2) must be shorted with appropriate decoupling (0.1 µF + 1 µF to REFM), and the internal buffer ensures 1 mV line regulation and 25 ppm/°C drift. The ADS7891IPFBT's internal reference meets all specified performance metrics - including 1.5 LSB INL - without external components, simplifying BOM and layout.

How does the BYTE pin affect data readout on the ADS7891IPFBT?

When BYTE = 0, the ADS7891IPFBT outputs the full 14-bit word (D13–D0) on DB13–DB0. When BYTE = 1, it folds the lower 6 bits (D5–D0) into the upper byte: D5 appears on DB13, D4 on DB12, down to D0 on DB8, while DB7–DB0 drive logic 0. This allows direct 8-bit microcontroller interfacing without external latches. The ADS7891IPFBT timing diagram (Figure 5) confirms D[5:0] validity occurs 25 ns after RD low with CS low, regardless of BYTE state.

What is the power consumption of the ADS7891IPFBT in nap mode versus full-speed operation?

In full-speed operation at 3 MSPS, the ADS7891IPFBT dissipates 85 mW (17 mA @ +VA = 5 V). In nap mode (A_PWD = low), supply current drops to 2–3 mA, reducing power to 10 mW - a >90% reduction. Power-down mode (PWD/RST = low >7.2 µs) further lowers current to 2.5 µA (12.5 µW). All modes retain pin compatibility and register state; the ADS7891IPFBT requires only 60 ns additional acquisition time after exiting nap mode.

Can the ADS7891IPFBT interface directly with a 3.3-V digital system?

Yes - the ADS7891IPFBT supports +VBD = 3.3 V (min 2.7 V, max 5.25 V) for its digital I/O supply, with VIH = +VBD −1 V and VIL = 0.8 V, ensuring reliable CMOS-level compatibility with 3.3-V FPGAs and microcontrollers. Its digital outputs (DB0–DB13, BUSY, etc.) are fully specified at 3.3 V, and conversion time increases only marginally (273 ns vs. 255 ns at 5 V). The ADS7891IPFBT's dual-supply architecture (+VA = 5 V, +VBD = 3.3 V) isolates analog and digital domains without level shifters.