Analog Devices Inc. LTC2291CUP#PBF

Overview

LTC2291CUP#PBF from Analog Devices (formerly Linear Technology) is a dual 12-bit, 25Msps low-power analog-to-digital converter operating from a single 3V supply (2.7V–3.4V), delivering 71.4dB SNR and 90dB SFDR at 5MHz input, with 110dB channel isolation at 100MHz. It serves as a high-fidelity digitizer for dual-channel RF and baseband signal acquisition in portable instrumentation and spectral analysis systems.

For engineers reviewing the LTC2291CUP#PBF datasheet, LTC2291CUP#PBF pinout, LTC2291CUP#PBF application, or LTC2291CUP#PBF equivalent, key selection criteria include its 25Msps sample rate, ±0.3LSB INL, 575MHz full-power bandwidth, flexible 1VP-P to 2VP-P differential input range, and support for multiplexed or separate digital output buses - all in a 64-pin QFN package with exposed thermal pad.

Technical Context

The LTC2291CUP#PBF implements a six-stage CMOS pipelined ADC architecture per channel, achieving 5-cycle pipeline latency and supporting independent or synchronized sampling via CLKA/CLKB inputs. Its integrated clock duty cycle stabilizer maintains AC performance across wide input duty cycles without external circuitry.

Each channel features programmable input range (±0.5V to ±1V) via SENSEA/SENSEB pins, internal 1.5V common-mode bias (VCMA/VCMB), and configurable output format (offset binary or 2's complement) via MODE pin. Dual reference structures (REFHA/REFLA, REFHB/REFLB) enable precise differential input termination and high channel isolation.

Key Specifications

Pinout & Package

Package: 64-lead (9mm × 9mm) plastic QFN with exposed thermal pad (Pin 65 = GND), θ_JA = 20°C/W, T_JMAX = 125°C. Exposed pad must be soldered to PCB ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel ADC applications.

Compared with AD9233BCPZ-25, LTC2291CUP#PBF provides true dual-channel synchronization and built-in clock stabilization in one package; compared with LTC2292CUP#PBF, it trades 15Msps speed for 85mW lower power - making it optimal for battery-constrained 25Msps applications where thermal headroom is limited.

Availability

LTC2291CUP#PBF is available at Aetrix Electronics and suitable for portable instrumentation, spectral analysis, and wireless communication test equipment requiring stable component supply, long-term obsolescence management, and traceable sourcing.

Supply support for LTC2291CUP#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, communications, automotive, and healthcare markets.

The LTC2291 belongs to ADI's high-speed precision ADC product line, designed specifically for applications demanding simultaneous dual-channel sampling, low power, and exceptional dynamic range in compact form factors.

FAQ

What is the maximum input frequency supported by the LTC2291CUP#PBF before SNR degradation exceeds 1dB?

The LTC2291CUP#PBF maintains 71.3dB SNR up to 70MHz input frequency (–1dBFS, 2V range), dropping to 70.9dB at 70MHz and 69.8dB at 140MHz. Its 575MHz full-power bandwidth ensures minimal amplitude roll-off, but SNR degrades gradually above 70MHz due to aperture jitter and front-end noise - design margins should cap input tones below 70MHz for <1dB SNR loss.

How does the MODE pin configuration affect the digital output timing of the LTC2291CUP#PBF?

The MODE pin on the LTC2291CUP#PBF controls both output data format (offset binary or 2's complement) and clock duty cycle stabilizer enable/disable. When MODE = GND, offset binary format is selected and duty cycle stabilization is off - requiring external 50% clock sources. When MODE = 1/3 VDD, stabilizer is enabled, relaxing clock source requirements while preserving t_D (CLK-to-data delay) within 1.4–5.4ns.

Can the LTC2291CUP#PBF operate with separate analog and digital supplies?

No - the LTC2291CUP#PBF uses a single 3V analog supply (VDD = 2.7V–3.4V) for core ADC operation, but features a separate output driver supply (OVDD = 0.5V–3.6V) to interface with diverse logic families. This separation allows the digital outputs to drive 1.8V, 2.5V, or 3.3V receivers independently of the analog supply, reducing noise coupling while maintaining signal integrity.

What is the purpose of the exposed thermal pad (Pin 65) on the LTC2291CUP#PBF QFN package?

The exposed thermal pad (Pin 65) on the LTC2291CUP#PBF is electrically connected to GND and serves dual functions: (1) thermal dissipation - lowering junction-to-board θ_JA from 20°C/W to ≤12°C/W when soldered to a 4-layer PCB with ≥4 thermal vias, and (2) grounding - minimizing analog ground bounce and improving PSRR. Leaving it unconnected degrades SNR by >2dB and risks thermal runaway at full sample rate.

Does the LTC2291CUP#PBF support independent power-down of each ADC channel?

Yes - the LTC2291CUP#PBF provides per-channel shutdown control via SHDNA/SHDNB and OEA/OEB pins. Setting SHDNA = VDD + OEA = VDD places Channel A in sleep mode (2mW), while SHDNB = GND + OEB = GND keeps Channel B active. This enables asymmetric power management - e.g., keeping one channel monitoring while the other sleeps - reducing average power in burst-mode acquisition systems.