Analog Devices Inc. LT8648SEV#PBF

Overview

LT8648SEV#PBF from Analog Devices is a 42V, 15A synchronous step-down Silent Switcher 2 regulator with second-generation EMI suppression architecture, 25ns minimum on-time, 200kHz–2.2MHz adjustable switching frequency, and integrated input/boost capacitors. It delivers up to 95.5% efficiency at 1MHz (12VIN→5VOUT) and supports automotive-grade operation from –40°C to 125°C.

For engineers reviewing the LT8648SEV#PBF datasheet, LT8648SEV#PBF pinout, LT8648SEV#PBF application, or LT8648SEV#PBF equivalent, key selection considerations include ultralow radiated EMI compliance (CISPR 25 Class 5), spread spectrum modulation capability, external compensation via VC pin for fast transient response, and thermal performance enabled by its 7mm × 4mm LQFN package with exposed ground pad.

Technical Context

The LT8648SEV#PBF implements peak current mode control with internal 0.6V reference and frequency foldback during startup/overcurrent. Its Silent Switcher 2 architecture integrates ceramic bypass capacitors inside the package for VIN and BST nodes, minimizing high-di/dt loop area and eliminating layout sensitivity for EMI performance.

It supports four operating modes via SYNC/MODE pin: Burst Mode (low IQ = 140µA), forced continuous mode (FCM), spread spectrum (±24% frequency modulation), and external synchronization. The VC pin enables loop compensation tuning, current sharing, and fast load-step response; CLKOUT provides 180° out-of-phase clock output for multi-regulator synchronization.

Key Specifications

Pinout & Package

LT8648SEV#PBF uses a 36-lead 7mm × 4mm LQFN package with exposed ground pad (pins 37–42). Thermal resistance θJA = 26°C/W (JEDEC board), improved to 15°C/W on demo board with proper PCB copper pour and via stitching.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Compared with LT8645SIV#PBF and MPQ4436AGL-AEC1-Z, the LT8648SEV#PBF uniquely combines 15A output, integrated EMI-reducing capacitors, and 2.2MHz operation-enabling smaller total solution size and guaranteed CISPR 25 Class 5 compliance without layout iteration.

Availability

LT8648SEV#PBF is available at Aetrix Electronics and suitable for automotive ADAS, industrial PLC, medical imaging, and 5G infrastructure applications requiring stable component supply, AEC-Q100 qualification, and ultralow EMI performance.

Supply support for LT8648SEV#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 LT8648S/LT8648SP product line delivers high-current, ultralow-EMI power conversion for noise-sensitive automotive and industrial systems where traditional buck regulators fail EMC testing or require costly filtering.

FAQ

What is the maximum output current supported by the LT8648SEV#PBF?

The LT8648SEV#PBF is rated for 15A continuous output current under specified thermal conditions. This rating assumes proper PCB layout with adequate copper area and thermal vias under the exposed ground pad. Derating applies above 85°C ambient; full 15A is guaranteed up to 125°C junction temperature with appropriate heatsinking.

Does the LT8648SEV#PBF require external input capacitors despite its integrated VIN bypass capacitors?

Yes, the LT8648SEV#PBF requires external input capacitors even with integrated VIN capacitors. The internal 10nF ceramic caps handle high-frequency switching noise, but external ≥10µF low-ESR ceramic plus bulk capacitance are mandatory to supply peak current and stabilize input voltage during load transients. Layout guidelines specify three capacitors: two small (<1µF) near the IC and one larger (≥10µF) nearby.

How does the LT8648SEV#PBF achieve CISPR 25 Class 5 compliance without external EMI filters?

The LT8648SEV#PBF achieves CISPR 25 Class 5 compliance through Silent Switcher 2 architecture: integrated ceramic capacitors for VIN and BST nodes minimize high-di/dt loop area, symmetrical SW pin layout cancels magnetic fields, and optimized internal gate drive reduces switching edge ringing. These features eliminate layout sensitivity and enable pass-level radiated emissions on standard 2-layer PCBs per test data in the datasheet (Figure G38–G39).

Can the LT8648SEV#PBF operate with an input voltage below 3V?

No, the LT8648SEV#PBF has a minimum input voltage of 2.6V (typical) at 400kHz and 2.75V (typical) at 2MHz, but the absolute functional minimum is 3V across the full temperature range per datasheet specifications. Operation below 3V may result in regulation loss, UVLO activation, or undefined behavior; it is not characterized or guaranteed.

What is the purpose of the exposed pad (pins 37–42) on the LT8648SEV#PBF package?

The exposed pad (pins 37–42) on the LT8648SEV#PBF is a thermal and electrical ground connection. It must be soldered to a large PCB copper area with multiple thermal vias to achieve specified θJA = 26°C/W (JEDEC board) or better. Leaving it unconnected degrades thermal performance significantly-θJA increases to >45°C/W-and risks thermal shutdown under 15A load.