Analog Devices Inc. LTC2251IUH#TRPBF

Overview

LTC2251IUH#TRPBF from Analog Devices (formerly Linear Technology) is a 10-bit, 125Msps low-noise pipelined analog-to-digital converter designed for high-frequency signal digitization in demanding communications and imaging systems. It operates from a single 3V supply (2.85V–3.4V), delivers 61.6dB SNR and 85dB SFDR at Nyquist, supports ±0.5V to ±1V differential input range, and features a 640MHz full-power bandwidth sample-and-hold stage.

For engineers reviewing the LTC2251IUH#TRPBF datasheet, LTC2251IUH#TRPBF pinout, LTC2251IUH#TRPBF application, or LTC2251IUH#TRPBF equivalent, key selection criteria include its 125Msps sampling rate, 32-pin QFN package with exposed ground pad, clock duty cycle stabilizer, flexible reference configuration via SENSE pin, and industrial temperature range (–40°C to +85°C).

Technical Context

The LTC2251IUH#TRPBF implements a six-stage CMOS pipelined ADC architecture with 5-cycle pipeline latency and integrated correction logic. Its sample-and-hold uses 3.5pF sampling capacitors and exhibits 0.2psRMS aperture jitter, enabling high-fidelity digitization of RF and IF signals up to 140MHz.

It supports dual output formats (offset binary or 2's complement) selected via MODE pin voltage, offers programmable input range (±0.5V to ±1V) via SENSE pin, and includes dedicated OF (over/underflow) flag output. The internal 1.5V VCM reference provides common-mode bias and can drive external circuitry.

Key Specifications

Pinout & Package

The LTC2251IUH#TRPBF is housed in a 32-lead (5mm × 5mm) plastic QFN package with exposed thermal pad (Pin 33) that must be soldered to PCB ground for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD9215BRUZ-125 and LTC2261IUP#PBF, the LTC2251IUH#TRPBF uniquely combines 125Msps speed with on-chip VCM, SENSE-programmable range, and duty cycle stabilization - reducing external component count and simplifying layout in space- and power-constrained RF digitizers.

Availability

LTC2251IUH#TRPBF is available at Aetrix Electronics and suitable for wireless infrastructure, medical ultrasound, spectral analysis, and portable RF test equipment requiring stable component supply across industrial temperature grades and long production lifecycles.

Supply support for LTC2251IUH#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.

The LTC2251IUH#TRPBF belongs to ADI's high-speed precision ADC product line, engineered specifically for wideband, low-noise digitization in communications infrastructure, medical imaging, and instrumentation where SNR, SFDR, and thermal stability are critical.

FAQ

What is the operating temperature range for the LTC2251IUH#TRPBF?

The LTC2251IUH#TRPBF is rated for industrial operation from –40°C to +85°C. This specification is validated across all AC and DC parameters in the datasheet, including SNR, SFDR, INL, and DNL. The "I" grade designation in the part number explicitly confirms this extended temperature range, making LTC2251IUH#TRPBF suitable for deployment in outdoor base stations, medical scanners, and field instruments where ambient conditions exceed commercial limits.

Does the LTC2251IUH#TRPBF require an external reference voltage?

No, the LTC2251IUH#TRPBF includes an internal 1.5V bandgap reference and supports fully self-contained operation using its internal reference. The SENSE pin allows configuration of ±0.5V or ±1V differential input range without external reference components. External references may be used for higher accuracy, but are not required - the LTC2251IUH#TRPBF functions correctly with only VDD, OVDD, and proper decoupling.

How does the MODE pin affect the output format and clock stabilizer in the LTC2251IUH#TRPBF?

The MODE pin on the LTC2251IUH#TRPBF controls both output coding format and clock duty cycle stabilizer state. Grounding MODE selects offset binary output with stabilizer disabled; applying 1/3 VDD enables offset binary with stabilizer active; 2/3 VDD selects 2's complement with stabilizer active; and tying to VDD selects 2's complement with stabilizer off. This dual-function pin eliminates the need for separate control lines, simplifying interface design while maintaining flexibility for timing-critical systems.

Can the LTC2251IUH#TRPBF interface directly with a 1.8V FPGA I/O bank?

Yes, the LTC2251IUH#TRPBF supports direct interfacing with 1.8V FPGA I/O through its independent OVDD supply pin (Pin 21). When OVDD is set to 1.8V, the D0–D9 outputs meet 1.8V LVCMOS logic thresholds (VOH ≥ 1.79V, VOL ≤ 0.09V at 1.6mA), eliminating level shifters. This capability is confirmed in the Digital Outputs section of the datasheet and applies across the full industrial temperature range for LTC2251IUH#TRPBF.

What is the purpose of the OF (Over/Under Flow) pin on the LTC2251IUH#TRPBF?

The OF pin on the LTC2251IUH#TRPBF is an active-high, open-drain output that asserts when the analog input exceeds ±FS/2 - indicating saturation or clipping. It provides real-time overflow detection without requiring post-processing, enabling immediate AGC adjustment, alarm triggering, or data discard in high-speed streaming applications. The OF signal is synchronized to the data output and reflects the current conversion result, making LTC2251IUH#TRPBF suitable for closed-loop signal conditioning systems.