Analog Devices Inc. LTC3115HFE-2#PBF

Overview

LTC3115HFE-2#PBF from Analog Devices is a 40V, 2A monolithic synchronous buck-boost DC/DC converter optimized for fast input transients (<1ms), with 2.7V–40V input/output voltage range, programmable 100kHz–2MHz switching frequency, and AEC-Q100 qualification for automotive use in 24V/28V industrial and telecom power systems.

For engineers reviewing the LTC3115HFE-2#PBF datasheet, LTC3115HFE-2#PBF pinout, LTC3115HFE-2#PBF application, or LTC3115HFE-2#PBF equivalent, key selection considerations include its wide VIN/VOUT compatibility, thermal rating up to 150°C junction, Burst Mode® quiescent current (30µA no-load), internal soft-start, and 20-lead TSSOP package with exposed PGND pad for enhanced thermal performance.

Technical Context

The LTC3115HFE-2#PBF implements a four-switch synchronous buck-boost topology with proprietary mode-transition control that ensures seamless regulation when VIN < VOUT (boost), VIN > VOUT (buck), or VIN ≈ VOUT (buck-boost boundary), eliminating output transients and subharmonic oscillation. Its voltage-mode PWM control loop uses an internal 1000mV reference and external compensation via VC/FB pins.

It integrates dual high-side gate drivers (BST1/BST2), internal VCC LDO (4.45V regulated), programmable input UVLO (2.7V threshold), and reverse inductor current limiting (−1.5A). The device supports external clock synchronization up to 2MHz on PWM/SYNC and features 3µA shutdown current with output disconnect.

Key Specifications

Pinout & Package

Package: 20-lead plastic TSSOP (FE) with exposed PGND pad (Pin 21); thermally enhanced for TJMAX = 150°C, θJA = 38°C/W, θJC = 10°C/W. Exposed pad must be soldered to PCB ground plane for rated thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC3115IFE-2#PBF and MP2918GQ-Z, the LTC3115HFE-2#PBF uniquely delivers AEC-Q100 Grade H qualification, guaranteed 150°C operation, and proprietary seamless mode transition-critical for automotive cold-crank resilience and industrial high-temperature reliability where alternatives require design compromises in thermal margin or transient immunity.

Availability

LTC3115HFE-2#PBF is available at Aetrix Electronics and suitable for automotive power systems, industrial 24V/28V supplies, telecom equipment, and FireWire regulator applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.

Supply support for LTC3115HFE-2#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets.

The LTC3115-2 product line delivers high-voltage, high-efficiency buck-boost regulators engineered for automotive and industrial applications demanding wide input range, fast transient response, and extended temperature reliability-specifically targeting power systems with unstable or multi-source inputs.

FAQ

What is the maximum junction temperature rating for the LTC3115HFE-2#PBF?

The LTC3115HFE-2#PBF is rated for a maximum junction temperature of +150°C and is qualified per AEC-Q100 Grade H. This specification is guaranteed over the full −40°C to +150°C operating junction temperature range, enabling reliable operation in under-hood automotive and high-temperature industrial environments where the LTC3115HFE-2#PBF must sustain continuous thermal stress without derating.

How does the LTC3115HFE-2#PBF handle input voltage transients below 1ms?

The LTC3115HFE-2#PBF employs a proprietary low-noise switching algorithm that maintains seamless regulation during fast input transients (<1ms), including cold-crank dips to 4.5V and load-dump spikes up to 45V absolute maximum. Its four-switch architecture and voltage-mode control loop prevent output glitches, subharmonics, or mode-boundary discontinuities-ensuring uninterrupted power delivery to sensitive loads like ADAS sensors or infotainment processors.

Can the LTC3115HFE-2#PBF be synchronized to an external clock?

Yes, the LTC3115HFE-2#PBF supports external clock synchronization via the PWM/SYNC pin (Pin 19), accepting input frequencies from 100kHz to 2MHz. When driven by an external clock, the device operates in fixed-frequency PWM mode with matched timing, reducing EMI in systems with multiple synchronized converters-such as telecom base stations or multi-rail FPGA power supplies where the LTC3115HFE-2#PBF must align switching edges to avoid beat frequencies.

What is the purpose of the BST1 and BST2 pins on the LTC3115HFE-2#PBF?

BST1 (Pin 16) and BST2 (Pin 15) are flying capacitor terminals used to generate boosted gate drive voltages for the internal high-side N-channel MOSFETs (Switch A and Switch D). Each connects via a 0.1µF capacitor to its respective switch node (SW1 or SW2), enabling full enhancement of the high-side devices across the entire 2.7V–40V input range-critical for the LTC3115HFE-2#PBF's ability to sustain high efficiency in both buck and boost modes without external gate drivers.

Does the LTC3115HFE-2#PBF provide output disconnect in shutdown mode?

Yes, the LTC3115HFE-2#PBF features output disconnect during shutdown: when the RUN pin is pulled low, internal power switches open, isolating the output (PVOUT) from the input (PVIN) and preventing backfeed or leakage into the load. This function, combined with a typical 3µA shutdown supply current, makes the LTC3115HFE-2#PBF ideal for battery-powered systems requiring zero-load isolation and ultra-low standby power consumption.