Analog Devices Inc./Maxim Integrated LT3046ATC+

Overview

LT3046ATC+ from Analog Devices is an ultra-low-noise, ultra-high-PSRR linear regulator delivering 200mA output with 0.8μV_RMS (10Hz–100kHz) noise, 82dB PSRR at 1MHz, and 300mV dropout at full load - designed for powering RF signal chains including VCOs, PLLs, and LNAs where supply integrity directly impacts phase noise and dynamic range.

For engineers reviewing the LT3046ATC+ datasheet, LT3046ATC+ pinout, LT3046ATC+ application, or LT3046ATC+ equivalent, key selection criteria include verified 2.2nV/√Hz wideband noise density, programmable current limit via ILIM pin, precision 100μA SET pin reference, parallelability for noise reduction, and thermally enhanced 3mm × 3mm DFN-12 package with exposed GND pad.

Technical Context

The LT3046ATC+ implements a precision current-reference architecture followed by a high-gain voltage buffer, enabling unity-gain stability across its full 0.2V–19V output range while preserving constant noise, PSRR, and bandwidth regardless of V_OUT. Its dual-output-sense topology (OUT and OUTS pins) supports Kelvin sensing for optimal load regulation under fast transients.

It integrates reverse-battery and reverse-current protection, foldback current limiting active above 11V VIN–VOUT differential, programmable power-good threshold via PGFB resistor divider, and fast-startup mode triggered by PGFB voltage - all operating within –40°C to +125°C junction temperature range with ±0.5% initial SET pin accuracy.

Key Specifications

Pinout & Package

LT3046ATC+ uses a thermally enhanced 12-lead, 3mm × 3mm DFN package with exposed GND pad soldered to PCB ground plane for optimal thermal dissipation (θ_JA = 35°C/W). The package includes dual IN and dual OUT pins for low-impedance power routing and reduced PCB trace resistance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-noise linear regulator applications.

Compared with LT3045EDD#PBF and TPL7407LDR, the LT3046ATC+ uniquely delivers 200mA output in the smallest DFN package while maintaining the lowest measured noise floor (0.8μV_RMS) and highest PSRR (82dB @ 1MHz) among pin-compatible ultra-low-noise regulators - making it optimal for miniaturized RF and precision measurement systems.

Availability

LT3046ATC+ is available at Aetrix Electronics and suitable for RF power supplies, high-speed data converters, low-noise instrumentation, and post-regulation of switching supplies requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.

Supply support for LT3046ATC+ 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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Wilmington, MA, with design centers and manufacturing facilities worldwide.

The LT3046ATC+ belongs to Analog Devices' ultra-low-noise LDO family engineered specifically for noise-sensitive signal-chain applications - emphasizing spectral purity, PSRR, and precision regulation over raw current capability.

FAQ

What is the minimum output capacitance required for stable operation of the LT3046ATC+?

The LT3046ATC+ requires a minimum 4.7μF ceramic output capacitor with ESR below 20mΩ and ESL below 2nH for guaranteed stability across all operating conditions. Lower capacitance values risk oscillation or degraded transient response, especially under heavy load steps. Larger capacitors improve peak voltage suppression during fast load transients but increase start-up time when used with the SET pin bypass capacitor.

Can the LT3046ATC+ be used in parallel to reduce output noise?

Yes, the LT3046ATC+ supports direct paralleling without external ballast components. When two or more LT3046ATC+ devices share a common SET node and common OUTS connection, output noise reduces by √N and total output current scales linearly with N. This architecture maintains individual current limiting and thermal protection per unit while improving overall power delivery integrity.

What is the function of the OUTS pin on the LT3046ATC+ and how should it be connected?

The OUTS pin on the LT3046ATC+ is the noninverting input to the error amplifier and serves as the Kelvin sense point for output voltage regulation. It must be connected directly to the output capacitor's positive terminal and the load's high-side return path - not to the main OUT pin - to eliminate IR drop errors and ensure precise load regulation under dynamic current conditions. Floating or misrouting OUTS degrades accuracy and transient response.

Does the LT3046ATC+ provide reverse-current protection, and how does it behave during reverse input conditions?

Yes, the LT3046ATC+ includes integrated reverse-current protection. When the input voltage is reversed (e.g., battery inserted backward), the device behaves like a series diode - blocking reverse current flow into the IC and preventing negative voltage from appearing at the output. No external diode is needed, eliminating forward voltage drop and associated power loss. Reverse input voltage rating is –22V per Absolute Maximum Ratings.

How is the programmable current limit implemented on the LT3046ATC+ and what is its accuracy?

The LT3046ATC+ implements programmable current limiting via the ILIM pin: connecting a resistor R_ILIM between ILIM and GND sets the current limit as I_LIM ≈ 150mA × R_ILIM(kΩ). For example, a 1kΩ resistor yields ~150mA limit. Accuracy is typically ±10% over temperature and line, with internal foldback protection activating above 11V VIN–VOUT differential. The ILIM pin also provides a proportional 0–290mV current monitor output.