Analog Devices Inc. LTC3851AMPMSE-1#TRPBF

Overview

LTC3851AMPMSE-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 topology. It operates from 4V to 38V input, delivers 0.8V–5.5V output with ±1% accuracy, supports phase-lockable 250–750kHz switching, and features PGOOD monitoring and OPTI-LOOP® compensation. It is used in automotive power supplies requiring extended temperature operation.

For engineers reviewing the LTC3851AMPMSE-1#TRPBF datasheet, LTC3851AMPMSE-1#TRPBF pinout, LTC3851AMPMSE-1#TRPBF application, or LTC3851AMPMSE-1#TRPBF equivalent, key selection criteria include its –55°C to 150°C MP-grade temperature rating, RSENSE/DCR current sensing flexibility, 99% duty cycle capability for low-dropout operation, and selectable light-load modes (Burst Mode®, pulse-skipping, or forced CCM).

Technical Context

The LTC3851AMPMSE-1#TRPBF implements a voltage-mode-compensated current-mode control architecture with integrated transconductance error amplifier (gm = 2 mmho, GBW = 3 MHz) and slope compensation. Its OPTI-LOOP® compensation network minimizes required output capacitance by adapting loop response to wide ESR/capacitance variations.

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 across 250–750kHz while maintaining ±1% VFB accuracy over –55°C to 150°C.

Key Specifications

Pinout & Package

Package: 16-lead plastic MSOP with exposed thermal pad (Pin 17 = GND), θJA = 40°C/W, rated for –55°C to 150°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3851AIMSE-1#TRPBF and LM5116PWPR, the LTC3851AMPMSE-1#TRPBF uniquely combines extended –55°C to 150°C operation, integrated PGOOD, programmable soft-start/tracking, and phase-lockable frequency - making it the only option qualified for mission-critical automotive power conversion.

Availability

LTC3851AMPMSE-1#TRPBF is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLCs, and telecom base station bias supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC3851AMPMSE-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, serving aerospace, automotive, industrial, and communications markets.

The LTC3851A-1 product line delivers high-efficiency, robust synchronous buck controllers optimized for demanding power conversion in automotive, telecom, and industrial systems - emphasizing precision regulation, thermal resilience, and flexible control architecture.

FAQ

What is the operating temperature range of the LTC3851AMPMSE-1#TRPBF?

The LTC3851AMPMSE-1#TRPBF is an MP-grade device rated for continuous operation from –55°C to 150°C junction temperature. This specification is fully tested and guaranteed, distinguishing it from E-, I-, or H-grade variants. Its thermal performance is validated with θJA = 40°C/W in the 16-lead MSOP package, and the exposed pad (Pin 17) must be soldered to PCB ground for compliance.

How does the LTC3851AMPMSE-1#TRPBF implement output voltage tracking?

The LTC3851AMPMSE-1#TRPBF uses the TK/SS pin to enable both soft-start and supply tracking. An internal 1µA current charges an external capacitor for linear ramping (soft-start), or an external resistor divider from a master supply can be connected to TK/SS to achieve ratiometric or coincident tracking. During tracking, the controller regulates VFB to match the TK/SS voltage instead of the 0.8V reference - a behavior confirmed in the Applications Information section.

Does the LTC3851AMPMSE-1#TRPBF support both RSENSE and DCR current sensing?

Yes, the LTC3851AMPMSE-1#TRPBF supports both methods: SENSE+ and SENSE– pins accept either a discrete shunt resistor (RSENSE) or a DCR network across the inductor. DCR sensing eliminates power loss and cost of shunts, while RSENSE provides higher accuracy for current limiting. The datasheet confirms compatibility with both schemes and specifies ±1µA input bias current and 6V common-mode range for robust operation.

What protection features are integrated into the LTC3851AMPMSE-1#TRPBF?

The LTC3851AMPMSE-1#TRPBF integrates output overvoltage protection (OV comparator disabling TG and enabling BG), current foldback limiting during short circuits, undervoltage lockout on INTVCC (3.25V threshold), and anti-shoot-through logic between TG and BG drivers. It also includes a 17µs power-bad mask on PGOOD to prevent false triggering during transients - all verified in the Absolute Maximum Ratings and Electrical Characteristics tables.

Can the LTC3851AMPMSE-1#TRPBF be synchronized to an external clock?

Yes, the LTC3851AMPMSE-1#TRPBF supports external synchronization via the MODE/PLLIN pin, which functions as a phase detector input. When driven by a clean clock signal between 250kHz and 750kHz, the internal oscillator locks to it while operating in forced continuous mode. A series RC network on FREQ/PLLFLTR serves as the PLL loop filter - a configuration explicitly detailed in the "Frequency Selection and Phase-Locked Loop" section.