Analog Devices Inc. LTC2251IUH#PBF

Overview

LTC2251IUH#PBF from Analog Devices (formerly Linear Technology) is a 10-bit, 125Msps low-noise pipelined analog-to-digital converter operating from a single 3V supply (2.85V–3.4V), delivering 61.6dB SNR and 85dB SFDR at Nyquist for high-fidelity digitization of wideband RF and imaging signals in demanding communications and ultrasound systems.

For engineers reviewing the LTC2251IUH#PBF datasheet, LTC2251IUH#PBF pinout, LTC2251IUH#PBF application, or LTC2251IUH#PBF equivalent, key selection considerations include its 640MHz full-power bandwidth, clock duty cycle stabilizer, flexible ±0.5V to ±1V differential input range, and support for offset binary or 2's complement output formats via MODE pin configuration.

Technical Context

The LTC2251IUH#PBF implements a six-stage CMOS pipelined ADC architecture with 5-cycle pipeline latency, enabling deterministic timing for real-time signal processing. Its sample-and-hold front-end features 3.5pF sampling capacitors and supports both differential and single-ended analog drive, with VCM pin providing a buffered 1.5V common-mode bias.

Internal reference generation allows programmable input ranges via SENSE pin voltage selection (VCM = ±0.5V range; VDD = ±1V range), while the clock duty cycle stabilizer ensures consistent AC performance across wide input clock duty cycles (30%–70%). Output drivers are independently powered by OVDD (0.5V–3.6V), supporting interfacing with diverse logic families.

Key Specifications

Pinout & Package

32-lead (5mm × 5mm) plastic QFN package with exposed pad (Pin 33) soldered to ground for optimal thermal and electrical performance. Pin pitch: 0.5mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD9208BCPZ-500 and LTC2261IUP#PBF, the LTC2251IUH#PBF delivers optimal balance of 10-bit accuracy, 125Msps throughput, and sub-400mW power in a simple parallel CMOS interface - making it ideal for cost-sensitive, thermally constrained, or legacy-FPGA-based designs requiring proven analog performance without JESD204B complexity.

Availability

LTC2251IUH#PBF is available at Aetrix Electronics and suitable for wireless infrastructure, medical ultrasound, spectral analysis, and high-speed data acquisition requiring stable component supply, long-term industrial temperature support, and mature production qualification.

Supply support for LTC2251IUH#PBF 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#PBF belongs to ADI's high-speed precision ADC product line, designed specifically for applications demanding wide input bandwidth, low noise, and robust operation in thermally challenging environments - including communications receivers, medical imaging, and automated test equipment.

FAQ

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

The LTC2251IUH#PBF is rated for industrial operation from –40°C to +85°C (I-grade). This is confirmed by the "I" suffix in the part number and specified in the Absolute Maximum Ratings table. All key AC and DC parameters-including ±0.6LSB INL/DNL, 61.6dB SNR, and 85dB SFDR-are guaranteed across this full range, making LTC2251IUH#PBF suitable for deployed equipment in uncontrolled environments.

Does the LTC2251IUH#PBF require an external reference, or does it have an internal one?

The LTC2251IUH#PBF includes an internal 1.5V bandgap reference and supports both internal and external reference configurations. When SENSE is tied to VCM, the internal reference sets a ±0.5V input range; tying SENSE to VDD configures a ±1V range. External references can also be applied to REFL/REFH pins, but the internal reference is fully functional and optimized for low-noise performance without external components.

How does the MODE pin affect the output format and clock duty cycle stabilizer in the LTC2251IUH#PBF?

The MODE pin on the LTC2251IUH#PBF controls two functions simultaneously: output data format (offset binary vs. 2's complement) and clock duty cycle stabilizer enable/disable. GND selects offset binary + stabilizer off; 1/3VDD selects offset binary + stabilizer on; 2/3VDD selects 2's complement + stabilizer on; VDD selects 2's complement + stabilizer off. This dual functionality simplifies system-level configuration without additional control lines.

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

Yes - the LTC2251IUH#PBF supports OVDD from 0.5V to 3.6V, and its digital outputs are fully specified at OVDD = 1.8V. At that supply, VOH is guaranteed ≥1.79V and VOL ≤0.09V under 1.6mA load, meeting standard LVCMOS18 input thresholds. OGND must be connected to the FPGA's I/O ground, and proper decoupling (0.1µF ceramic) is required on OVDD.

What is the significance of the exposed pad (Pin 33) on the LTC2251IUH#PBF QFN package?

The exposed pad (Pin 33) on the LTC2251IUH#PBF is electrically connected to GND and serves as the primary thermal and low-impedance ground path. It must be soldered to a solid PCB ground plane using multiple thermal vias. Failure to do so degrades thermal resistance (θ_JA = 34°C/W only when properly mounted), increases junction temperature, and risks violating the 125°C T_JMAX limit under continuous 395mW operation.