Analog Devices Inc. LTC4371CMS#PBF

Overview

LTC4371CMS#PBF from Analog Devices (formerly Linear Technology) is a dual-channel negative-voltage ideal diode-OR controller that drives external N-channel MOSFETs to replace Schottky diodes in –48V telecom power systems. It delivers 15mV forward voltage drop, ±300V transient tolerance, and 220ns reverse-current turn-off time, enabling high-reliability redundant power ORing in AdvancedTCA and network routers.

For engineers reviewing the LTC4371CMS#PBF datasheet, LTC4371CMS#PBF pinout, LTC4371CMS#PBF application, or LTC4371CMS#PBF equivalent, key selection criteria include its dual N-channel gate drive capability, shunt-regulated VZ input for high-voltage biasing, fault detection via FAULTB open-drain output, and MSOP-10 package compatibility with industrial temperature range (0°C to 70°C).

Technical Context

The LTC4371CMS#PBF implements two independent servo loops-AMPA and AMPB-that regulate MOSFET source-drain voltage (∆VSD) to 15mV using Kelvin-sensed DA/SA and DB/SB inputs. Each loop drives GA/GB outputs with 5mA pull-up and 2A pull-down capability, achieving sub-220ns fault turn-off by detecting ∆VSD reversal.

Its VZ pin provides a 12.4V shunt regulator (50µA–10mA range) to bias VDD in high-voltage applications, while internal 130V clamps on DA/DB pins-combined with external series resistors-enable safe operation under ±300V transients without damage.

Key Specifications

Pinout & Package

Package: 10-Lead Plastic MSOP (3mm × 3mm footprint, 1.1mm height), rated for 0°C to 70°C ambient operation. Exposed pad not present in MSOP variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative-voltage ideal diode-OR controller applications.

Compared with LTC4370IMS#PBF, the LTC4371CMS#PBF adds full dual-channel autonomy and fault discrimination; compared with TPS2113APWR, it enables robust –48V infrastructure deployment with integrated transient hardening and diagnostic signaling-making it irreplaceable for carrier-grade power ORing.

Availability

LTC4371CMS#PBF is available at Aetrix Electronics and suitable for telecom power distribution, AdvancedTCA shelf management, and network router line card designs requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.

Supply support for LTC4371CMS#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 acquired Linear Technology in 2017 and maintains its precision analog and power management portfolio. The company specializes in high-reliability ICs for industrial, automotive, and communications infrastructure.

The LTC4371CMS#PBF belongs to Linear's Ideal Diode Controller product line, designed specifically for high-efficiency, fault-tolerant power ORing in negative-voltage telecom and datacom systems-prioritizing ultra-low loss, transient resilience, and diagnostic visibility.

FAQ

What is the maximum continuous voltage the DA and DB pins of the LTC4371CMS#PBF can withstand?

The DA and DB pins of the LTC4371CMS#PBF have an absolute maximum rating of –40V to +100V relative to VSS, but the device is designed to survive ±300V transients when protected by external series resistors (e.g., 20kΩ) that limit clamp current to ≤10mA for 6ms. Internal 130V clamps engage during overvoltage events, and sustained operation above 100V requires proper resistor sizing per Equation 8 in the datasheet. The LTC4371CMS#PBF relies on this external protection scheme-not internal ruggedization-to achieve lightning-survivable performance.

How does the LTC4371CMS#PBF achieve 15mV forward voltage regulation across varying load currents?

The LTC4371CMS#PBF uses dual high-gain servo amplifiers (AMPA and AMPB) that continuously compare Kelvin-sensed ∆VSD (via DA–SA and DB–SB pairs) against an internal 15mV reference. When ∆VSD deviates, the amplifier adjusts GA or GB output voltage to modulate the external N-channel MOSFET's R_DS(ON), forcing ∆VSD back to 15mV. At low loads, gate voltage is held near threshold; at high loads, gate is driven fully on until R_DS(ON)•I_LOAD dominates. This closed-loop control is intrinsic to the LTC4371CMS#PBF architecture and requires no external compensation.

Can the LTC4371CMS#PBF be used in positive-voltage ORing applications?

No-the LTC4371CMS#PBF is explicitly designed for negative-voltage systems (e.g., –48V) and cannot be reconfigured for positive-rail operation. Its DA/DB inputs are referenced to VSS (system return), GA/GB outputs swing from VSS to VDD, and internal amplifiers expect negative ∆VSD polarity during normal conduction. Attempting positive-voltage use violates absolute maximum ratings and disables servo regulation. For positive-rail ORing, Analog Devices offers the LTC4373 or discrete solutions-not the LTC4371CMS#PBF.

What is the role of the VZ pin on the LTC4371CMS#PBF, and how is it typically configured?

The VZ pin on the LTC4371CMS#PBF is a shunt-regulated 12.4V reference input that enables direct biasing of VDD from high-voltage rails like –48V. In standard implementation, a single resistor (e.g., 30kΩ) connects VZ to return, while VDD is tied to VZ and bypassed with 2.2µF. This configuration allows the LTC4371CMS#PBF to operate without an auxiliary DC/DC converter. VZ also controls gate pull-up strength: >11.8V enables 5mA drive; <1.15V permanently enables it; 1.35–10.4V disables it-providing flexible biasing for diverse system architectures.

How does the FAULTB pin on the LTC4371CMS#PBF indicate MOSFET or fuse failure?

The FAULTB pin on the LTC4371CMS#PBF is an open-drain output that pulls low (<0.4V at 5mA sink) when either channel's ∆VSD exceeds 200mV while the corresponding gate (GA or GB) is fully driven on-indicating an open-circuit condition in the MOSFET or upstream fuse. This detection is independent per channel and latches until power cycle or fault clearance. FAULTB can directly drive an LED (with pull-up resistor) or optoisolator for system-level fault reporting. Its behavior is inherent to the LTC4371CMS#PBF's internal fault logic and requires no external configuration.