Analog Devices Inc. LTC2921IGN-3.3#TRPBF

Overview

LTC2921IGN-3.3#TRPBF from Analog Devices (formerly Linear Technology) is a 3-supply power tracking and monitoring IC for multi-rail systems, featuring ±1% accurate 0.5V monitor thresholds, adjustable electronic circuit breaker (50mV trip), and GATE drive output (9.1V typical at VCC = 3.3V) for external N-channel MOSFETs. It supports synchronized ramp-up of 5V, 3.3V, and 2.5V supplies in desktop computers and telecom infrastructure.

For engineers reviewing the LTC2921IGN-3.3#TRPBF datasheet, LTC2921IGN-3.3#TRPBF pinout, LTC2921IGN-3.3#TRPBF application, or LTC2921IGN-3.3#TRPBF equivalent, key selection considerations include its 16-pin narrow SSOP package, –40°C to 85°C industrial temperature grade, guaranteed 50mV circuit breaker trip voltage, 1.2V TIMER threshold, and 0.5V monitor input accuracy across temperature.

Technical Context

The LTC2921IGN-3.3#TRPBF implements a deterministic 6-step power-on sequencing controller with dual TIMER-based delays (600ms/µF), automatic remote sense switching via three integrated N-channel feedback switches (R_DS(ON) ≤ 10Ω), and latch-based fault handling for undervoltage lockout, monitor error, and circuit breaker trip events.

Its control logic uses internal charge-pump–derived rails (VPUMP ≈ 9.1V at VCC = 3.3V) to drive GATE and PG outputs, while V1–V4 inputs monitor supply voltages via precision 0.5V comparators with glitch immunity and 0.7V overvoltage detection - all operating with <2.5mA supply current at 3.3V.

Key Specifications

Pinout & Package

Package: 16-lead narrow plastic SSOP (GN), 0.15mm lead pitch, JEDEC MO-179AA compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-rail power tracking applications.

Compared with LTC2921IGN-3.3#TRPBF, the LTC2921IGN#TRPBF requires VCC redesign but offers higher GATE drive for 5V systems, while TPS652860RGER integrates conversion but sacrifices remote sensing and fine-grained ramp control - making LTC2921IGN-3.3#TRPBF optimal for high-precision, externally switched multi-rail platforms.

Availability

LTC2921IGN-3.3#TRPBF is available at Aetrix Electronics and suitable for desktop computers, telecom infrastructure, and industrial PLCs requiring stable component supply with guaranteed long-term availability and full industrial temperature support.

Supply support for LTC2921IGN-3.3#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.

The LTC2921 series was designed specifically for hardware-based, glitch-immune power sequencing in mission-critical multi-voltage systems where firmware-controlled timing is unacceptable.

FAQ

What is the maximum allowable voltage on the GATE pin of the LTC2921IGN-3.3#TRPBF?

The LTC2921IGN-3.3#TRPBF includes an internal clamp limiting GATE voltage to ≤12.2V relative to ground. This protects external N-channel MOSFETs from overvoltage stress during ramp-up. At VCC = 3.3V, the typical GATE output reaches 9.1V, well within safe operating limits for logic-level FETs. Exceeding 12.2V risks permanent damage to the internal charge pump driver stage of the LTC2921IGN-3.3#TRPBF.

Can the LTC2921IGN-3.3#TRPBF monitor fewer than four supplies?

Yes - unused V2, V3, and V4 pins on the LTC2921IGN-3.3#TRPBF must be tied to a used monitor input (e.g., V1) or to a valid supply rail within the 0.5V–0.7V window. Leaving them floating violates the requirement that all four monitor inputs remain within threshold bounds to initiate sequencing. The LTC2921IGN-3.3#TRPBF does not disable unused inputs automatically; external connection is mandatory for reliable operation.

How is the circuit breaker on the LTC2921IGN-3.3#TRPBF reset after tripping?

The LTC2921IGN-3.3#TRPBF circuit breaker is reset by pulling the V1 pin below 0.490V for >150µs after the overcurrent condition ends. Alternatively, a VCC undervoltage event lasting >10µs will also clear the fault latch. The LTC2921IGN-3.3#TRPBF does not auto-reset; deliberate reset action is required to prevent uncontrolled re-engagement of faulty loads. This ensures safety-critical systems maintain fail-safe behavior.

Does the LTC2921IGN-3.3#TRPBF support remote sensing for all monitored supplies?

No - the LTC2921IGN-3.3#TRPBF provides three integrated remote sense switches (S1/D1, S2/D2, S3/D3) for compensation of IR drop across external pass FETs, but it does not assign dedicated switches per supply. These switches are shared resources activated sequentially after GATE ramp completes. The LTC2921IGN-3.3#TRPBF supports remote sensing for up to three supplies simultaneously; fourth and fifth rails require external circuitry.

What is the minimum recommended TIMER capacitor value for stable operation of the LTC2921IGN-3.3#TRPBF?

The LTC2921IGN-3.3#TRPBF requires the TIMER pin voltage to fall below 150mV before initiating a delay cycle. For reliable timing, Analog Devices specifies ≥60pF minimum capacitance to suppress noise-induced false triggers. Below 60pF, stray PCB capacitance dominates, causing inconsistent delay timing and potential sequencing failures. Always use C0G/NP0 dielectric capacitors with tight tolerance for critical applications involving the LTC2921IGN-3.3#TRPBF.