Analog Devices Inc. LTC3621EMS8E-23.3#PBF

Overview

LTC3621EMS8E-23.3#PBF from Analog Devices is a 2.25MHz, 3.3V fixed-output synchronous step-down regulator delivering up to 1A output current with 3.5µA quiescent current and ±1% output voltage accuracy. It operates from 2.7V to 17V input, supports Burst Mode™, pulse-skipping, and forced continuous operation, and integrates Power Good (PGOOD) and independent SGND for noise-sensitive industrial power rails.

For engineers reviewing the LTC3621EMS8E-23.3#PBF datasheet, LTC3621EMS8E-23.3#PBF pinout, LTC3621EMS8E-23.3#PBF application, or LTC3621EMS8E-23.3#PBF equivalent, this page delivers verified electrical parameters, MS8E package terminal mapping, thermal performance data (θJA = 40°C/W), and validated alternative options for automotive-grade 3.3V point-of-load conversion.

Technical Context

The LTC3621EMS8E-23.3#PBF implements a constant-frequency peak current mode control architecture with internal compensation, enabling stable regulation across 2.7V–17V input while maintaining 3.3V ±1% accuracy over temperature and load. Its 2.25MHz switching frequency supports compact external components including 2.2µH inductors and ceramic capacitors.

It features three selectable operating modes via the MODE/SYNC pin: Burst Mode™ (3.5µA IQ, 400mA clamp), pulse-skipping (low ripple), and forced continuous (zero-load capability). The MS8E package includes dedicated SGND and PGOOD pins with ±7.5% detection window and 32-cycle blanking delay.

Key Specifications

Pinout & Package

8-lead plastic MSOP (MS8E) package with exposed pad (Pin 9 = GND), thermally enhanced for high-power density. Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output buck regulator applications.

Compared with TPS62130ARGTR and MP2315GJ-Z, the LTC3621EMS8E-23.3#PBF provides superior light-load efficiency (3.5µA vs ≥17µA), integrated PGOOD with blanking, and signal/power ground separation - making it uniquely suited for battery-backed, automotive, and industrial applications demanding reliability and low-noise operation.

Availability

LTC3621EMS8E-23.3#PBF is available at Aetrix Electronics and suitable for portable-handheld scanners, industrial embedded computing, and automotive infotainment systems requiring stable component supply with long-term lifecycle assurance.

Supply support for LTC3621EMS8E-23.3#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC3621 series is designed for high-efficiency, low-quiescent-current point-of-load conversion in space-constrained and battery-sensitive applications - emphasizing ultralow IQ, fixed-frequency stability, and robust thermal performance in MSOP and DFN packages.

FAQ

What is the output voltage tolerance of the LTC3621EMS8E-23.3#PBF over temperature?

The LTC3621EMS8E-23.3#PBF delivers a fixed 3.3V output with ±1% accuracy over its full operating junction temperature range of –40°C to 125°C. This is confirmed in the Electrical Characteristics table (page 4), where VOUT for LTC3621-23.3 variants is specified as 3.267V (min) to 3.333V (max) under E/I-grade conditions. The part achieves this via a precision 0.6V internal reference and trimmed feedback network.

Does the LTC3621EMS8E-23.3#PBF require an external feedback resistor divider?

No, the LTC3621EMS8E-23.3#PBF does not require an external feedback resistor divider. As a factory-programmed fixed-output variant, its FB pin is internally connected to the 3.3V output. Per the Pin Functions section (page 8), "For Fixed VOUT options, connect the FB pin directly to VOUT" - and the datasheet confirms FB is tied internally in -23.3 versions, eliminating external component count and layout sensitivity.

How does the PGOOD function work on the LTC3621EMS8E-23.3#PBF?

The PGOOD pin on the LTC3621EMS8E-23.3#PBF is an open-drain output that goes high when VOUT is within ±7.5% of 3.3V (i.e., 3.05V–3.55V) and remains high for ≥32 switching cycles after entering regulation. If VOUT falls outside this window, PGOOD pulls low via a 275Ω internal FET. This blanking delay prevents false triggering during load transients - a key feature for reliable system power sequencing in industrial controllers.

Can the LTC3621EMS8E-23.3#PBF synchronize to an external clock?

Yes, the LTC3621EMS8E-23.3#PBF can synchronize to an external clock via the MODE/SYNC pin (Pin 7). When driven with a TTL/CMOS clock signal, it locks to frequencies within ±40% of its nominal 2.25MHz (i.e., 1.35MHz–3.15MHz). Upon sync engagement, the device enters forced continuous mode and eliminates beat frequencies - essential for EMI-sensitive automotive and medical applications.

What thermal performance can be expected from the LTC3621EMS8E-23.3#PBF in a typical 4-layer PCB layout?

In a standard 4-layer PCB with 2oz copper, 1in² exposed pad area, and adequate thermal vias, the LTC3621EMS8E-23.3#PBF achieves θJA ≈ 40°C/W (per datasheet page 2). At 1A output with 12V input and 3.3V output, power dissipation is ~1.5W, resulting in ~60°C junction rise above ambient - well within its 125°C max junction rating. Derating begins above 100°C, so airflow or larger copper areas are recommended for sustained 1A operation at high ambient temperatures.