Analog Devices Inc. LT1994IDD#TRPBF

Overview

LT1994IDD#TRPBF from Analog Devices (formerly Linear Technology) is a fully differential input/output amplifier optimized for single-supply ADC driving, featuring rail-to-rail output swing, 3nV/√Hz input voltage noise, –94dBc distortion at 1MHz (2VP-P), adjustable VOCM pin, and 85mA output current capability. It enables precise single-ended-to-differential conversion with common-mode level shifting for low-voltage, high-resolution data acquisition systems.

For engineers reviewing the LT1994IDD#TRPBF datasheet, LT1994IDD#TRPBF pinout, LT1994IDD#TRPBF application, or LT1994IDD#TRPBF equivalent, key selection considerations include its differential gain stability, VOCM-controlled output common-mode setting, shutdown current of 225μA, 70MHz gain-bandwidth product, and compatibility with 2.375V–12.6V supply operation in industrial temperature range (–40°C to 85°C).

Technical Context

The LT1994IDD#TRPBF employs an internal common-mode feedback path that enforces accurate phase balance between OUT+ and OUT–, reducing even-order harmonics and enabling high-fidelity signal conditioning. Its differential architecture isolates output common-mode voltage from input common-mode variations via the VOCM pin, supporting precise level translation independent of source impedance.

It operates as a unity-gain stable, wideband amplifier with 65V/μs slew rate and 70MHz gain-bandwidth, delivering 2VP-P signals into 800Ω loads while maintaining <2mV DC offset and >85dB CMRR over frequency. The SHDN pin provides hardware-controlled power-down with sub-μs transition time and open-collector-like output behavior in shutdown mode.

Key Specifications

Pinout & Package

LT1994IDD#TRPBF is housed in an 8-lead (3mm × 3mm) plastic DFN package with exposed pad (Pin 9) soldered to V– for thermal and electrical grounding. The package supports high-density PCB layouts and offers θJA = 43°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fully differential amplifier applications.

Compared with ADA4941-1ARZ and THS4561IRGET, the LT1994IDD#TRPBF uniquely combines VOCM adjustability, hardware shutdown, 70MHz GBW, and 3nV/√Hz noise in a single industrial-grade DFN package - making it optimal for precision, power-aware, ADC-coupled signal chains requiring flexible level translation.

Availability

LT1994IDD#TRPBF is available at Aetrix Electronics and suitable for instrumentation front-ends, high-speed data acquisition systems, and medical imaging signal chains requiring stable component supply, guaranteed industrial temperature operation (–40°C to 85°C), and long-term production continuity.

Supply support for LT1994IDD#TRPBF 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

Analog Devices, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.

The LT1994IDD#TRPBF belongs to Linear's precision differential amplifier product line, designed specifically to simplify high-fidelity, low-voltage interface between sensors, signal sources, and modern differential-input ADCs in space- and power-constrained systems.

FAQ

What is the operating temperature range for LT1994IDD#TRPBF?

The LT1994IDD#TRPBF is rated for industrial operation from –40°C to +85°C, with full electrical specifications guaranteed across this range. Its junction temperature limit is 150°C, and thermal resistance (θJA) is 43°C/W in the 3mm × 3mm DFN package - enabling reliable use in enclosed industrial enclosures without forced airflow.

How does the VOCM pin function in LT1994IDD#TRPBF?

The VOCM pin on the LT1994IDD#TRPBF sets the average voltage of OUT+ and OUT–, defining the output common-mode level independently of input common-mode voltage. Internally biased to mid-supply, it can be overdriven with an external reference; its Thevenin resistance is ~40kΩ, and it must be bypassed with ≥0.1μF ceramic capacitor to ground for noise immunity.

Can LT1994IDD#TRPBF drive ADCs like the LTC1403A-1 directly?

Yes - the LT1994IDD#TRPBF is explicitly characterized driving the LTC1403A-1, as shown in the typical application (Figure TA01). With matched 499Ω feedback resistors, 2VP-P single-ended input, and VOCM = 1.5V, it achieves SFDR = 93dB and <120ns settling, meeting the timing and distortion requirements of this 12-bit, 2.8Msps SAR ADC.

What is the shutdown behavior of LT1994IDD#TRPBF?

When the SHDN pin is pulled ≥2.1V below V+, the LT1994IDD#TRPBF enters shutdown, drawing only 225μA at 3V. Outputs become high-impedance with steering diodes to both supplies, and internal bias currents are disabled. Turn-on/off time is ~1μs, and the pin features a ~55kΩ Thevenin impedance to V+ for robust logic-level interfacing.

Does LT1994IDD#TRPBF require external compensation or gain-setting components?

No - the LT1994IDD#TRPBF is unity-gain stable and requires no external compensation. Gain is set solely by external feedback resistors (e.g., RI and RF in Figure 1); typical configurations use matched 499Ω resistors for unity differential gain. Layout best practices - short traces, ground plane clearance near IN+/IN–, and proper VOCM bypassing - are essential for achieving datasheet performance.