Analog Devices Inc./Maxim Integrated LT3046ATC+T

Overview

LT3046ATC+T from Analog Devices is an ultra-low-noise, ultra-high-PSRR linear regulator delivering 200mA output current with 300mV dropout, 0.8μVRMS (10Hz–100kHz) output noise, and 82dB PSRR at 1MHz-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+T datasheet, LT3046ATC+T pinout, LT3046ATC+T application, or LT3046ATC+T equivalent, key selection criteria include verified 2.2nV/√Hz spectral noise at 10kHz, programmable 0.2V–19V output via single resistor, ±0.5% SET pin current accuracy, and validated DFN-12 (3mm × 3mm) thermal performance under 200mA continuous load.

Technical Context

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

It integrates programmable current limiting (via ILIM pin with 150mA/kΩ scale factor), fast-startup circuitry activated by PGFB, and reverse-battery/reverse-current protection-enabling robust operation in battery-powered instrumentation without external diodes or foldback compensation.

Key Specifications

Pinout & Package

LT3046ATC+T is housed in a thermally enhanced, lead-free, RoHS-compliant 12-lead 3mm × 3mm DFN package with exposed pad electrically connected to GND for optimal thermal dissipation (θJA = 35°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT3045EDD#PBF and TPL7407LDR, the LT3046ATC+T uniquely combines programmable output, ultra-low 1/f noise, and integrated power-good signaling-making it the only option among the three suitable for RF PLL biasing and high-resolution data acquisition where both spectral purity and system-level monitoring are mandatory.

Availability

LT3046ATC+T is available at Aetrix Electronics and suitable for RF power supplies, high-speed data converters, precision instrumentation, and post-regulation applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LT3046ATC+T 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, serving industrial, communications, automotive, and healthcare markets with precision technologies.

The LT3046ATC+T belongs to Analog Devices' ultra-low-noise LDO family, engineered specifically for noise-critical analog signal chains-including RF, metrology, and high-fidelity audio-where conventional regulators introduce unacceptable spectral contamination.

FAQ

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

The LT3046ATC+T requires a minimum 4.7μF ceramic output capacitor with ESR below 20mΩ and ESL below 2nH. This value ensures phase margin >60° across all operating conditions and prevents oscillation during large load transients. Using lower capacitance or higher-ESR types risks instability and degraded PSRR-verified in Figure 22 of the LT3046 datasheet Rev. B.

Can the LT3046ATC+T be used in parallel configurations, and what design considerations apply?

Yes, the LT3046ATC+T supports direct paralleling without external ballast resistors due to its precision current-source architecture. When paralleled, output noise reduces by √N, current capacity scales linearly, and thermal load spreads across devices. Key requirements include matched PCB layout, identical SET and output capacitors per device, and shared PGFB/EN/UV nets for synchronized startup-details in Applications Information Section 25 of the datasheet.

How does the SET pin current accuracy affect output voltage tolerance in the LT3046ATC+T?

The LT3046ATC+T features ±0.5% initial accuracy on its 100μA SET pin current, which directly determines output voltage via V_OUT = 100μA × R_SET. Combined with standard 1% resistor tolerance, total output error remains within ±1.5% at room temperature-enabling accurate, resistor-programmed outputs from 0.2V to 19V without trimming. Temperature drift adds <±0.01%/°C additional error.

Does the LT3046ATC+T provide reverse-current protection, and how is it implemented?

Yes, the LT3046ATC+T includes integrated reverse-current protection. When V_IN < V_OUT, internal circuitry blocks conduction from OUT to IN, preventing backfeed into upstream supplies or batteries. This is achieved without external diodes and remains active across the full –40°C to +125°C junction temperature range-confirmed in Absolute Maximum Ratings Table 2 and Protection Features Section 37.

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

The OUTS pin is the non-inverting input of the error amplifier and serves as the remote output voltage sense point. For optimal load regulation and transient response, OUTS must be Kelvin-connected directly to the load or output capacitor's high-side terminal-separate from the main GND return path. This eliminates IR drop errors caused by PCB trace resistance, ensuring <±0.01% load regulation even at 200mA step loads.