Analog Devices Inc. LTC3851AEMSE-1#TRPBF

Overview

LTC3851AEMSE-1#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance synchronous step-down switching regulator controller driving dual N-channel MOSFETs in constant-frequency current-mode operation. It delivers 0.8V to 5.5V output with ±1% accuracy, supports 4V–38V input, operates up to 750kHz, and features precision power-good monitoring and adjustable soft-start. It is used in telecom intermediate bus converters requiring stable, high-efficiency regulation under wide input and load transients.

For engineers reviewing the LTC3851AEMSE-1#TRPBF datasheet, LTC3851AEMSE-1#TRPBF pinout, LTC3851AEMSE-1#TRPBF application, or LTC3851AEMSE-1#TRPBF equivalent, key selection criteria include its 0.8V reference tolerance, phase-lockable frequency range (250–750kHz), PGOOD open-drain output behavior, OPTI-LOOP® compensation flexibility, and thermal performance in the 16-lead MSOP package with exposed pad.

Technical Context

The LTC3851AEMSE-1#TRPBF implements a constant-frequency current-mode control architecture with an internal transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and slope compensation. Its ITH pin serves as both error amplifier output and current threshold control, enabling precise peak-current limiting and transient response tuning via OPTI-LOOP®.

It integrates dual gate drivers (TG/BG) with matched 25ns transition times, 30ns dead-time control, and on-resistance specs (TG RUP = 2.2Ω, BG RDOWN = 1.1Ω). The improved PLL versus LTC3851-1 enables robust synchronization to external clocks up to 750kHz while maintaining forced continuous mode during sync.

Key Specifications

Pinout & Package

Package: 16-lead plastic MSOP (MSE) with exposed thermal pad (Pin 17 = GND), rated for –40°C to 125°C junction temperature (θJA = 35–40°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck controller applications.

Compared with LTC3851AIMSE-1#TRPBF, the LTC3851AEMSE-1#TRPBF offers identical functionality but with extended temperature characterization assurance rather than guaranteed test coverage; compared with MP2918GL-Z, it provides superior design flexibility (frequency adjust, DCR sensing, three light-load modes) at the cost of external MOSFETs and slightly higher layout complexity.

Availability

LTC3851AEMSE-1#TRPBF is available at Aetrix Electronics and suitable for telecom intermediate bus converters, industrial PLC power supplies, and automotive infotainment core supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC3851AEMSE-1#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The LTC3851A series belongs to Linear's high-efficiency synchronous controller product line, designed specifically for demanding DC/DC conversion in telecom, industrial, and automotive systems where precision, reliability, and thermal robustness are critical.

FAQ

What is the absolute maximum input voltage rating for the LTC3851AEMSE-1#TRPBF?

The LTC3851AEMSE-1#TRPBF has an absolute maximum input supply voltage (VIN) rating of 40V. Exceeding this voltage-even momentarily-may cause permanent damage. The recommended operating range remains 4V to 38V, and the INTVCC regulator derives power from VIN, so maintaining VIN within specification ensures stable internal biasing and gate drive performance for the LTC3851AEMSE-1#TRPBF.

How does the PGOOD pin on the LTC3851AEMSE-1#TRPBF behave during startup and fault conditions?

The PGOOD pin on the LTC3851AEMSE-1#TRPBF is an open-drain output that remains low during soft-start, shutdown (RUN < 1.1V), or whenever VFB falls outside the ±10% window around 0.8V. It transitions high only after VFB stabilizes within 0.72V–0.88V and remains high for ≥17µs. This 17µs mask prevents false trips from transient noise. The LTC3851AEMSE-1#TRPBF requires an external pull-up resistor (to ≤6V) to assert logic-high status.

Can the LTC3851AEMSE-1#TRPBF support DCR current sensing, and what design considerations apply?

Yes, the LTC3851AEMSE-1#TRPBF supports both RSENSE and DCR current sensing via SENSE+ and SENSE– pins. For DCR sensing, an RC network filters inductor DCR voltage; component values must compensate for temperature drift and ensure signal bandwidth exceeds switching frequency. The LTC3851AEMSE-1#TRPBF's ±1µA sense pin bias current and wide common-mode range (0–6V) simplify DCR implementation while maintaining accuracy across temperature.

What is the purpose of the TK/SS pin on the LTC3851AEMSE-1#TRPBF, and how is it configured for tracking?

On the LTC3851AEMSE-1#TRPBF, the TK/SS pin controls output voltage ramp rate during startup and enables supply tracking. For ratiometric tracking, connect a resistor divider from a master supply to TK/SS and GND, scaling the master voltage to match the target VOUT ratio. For coincident tracking, tie TK/SS directly to the master supply. The LTC3851AEMSE-1#TRPBF regulates VFB to TK/SS voltage until it reaches 0.8V, ensuring synchronized rise/fall of output rails.

Does the LTC3851AEMSE-1#TRPBF require external components for phase-locking, and what is the recommended configuration?

Yes, the LTC3851AEMSE-1#TRPBF requires an external RC network between FREQ/PLLFLTR and GND to serve as the PLL loop filter when synchronizing to an external clock applied to MODE/PLLIN. A typical configuration uses a 10kΩ resistor and 1nF capacitor. The external clock must be 250–750kHz and applied before enabling RUN; if not, a parallel resistor (e.g., 100kΩ) across the RC network prevents low-frequency startup glitches. This configuration ensures stable lock and jitter suppression for the LTC3851AEMSE-1#TRPBF.