Analog Devices Inc. LTC3895HFE#PBF

Overview

LTC3895HFE#PBF from Analog Devices (formerly Linear Technology) is a high-voltage, synchronous step-down DC/DC controller driving all-N-channel MOSFETs with input voltage support up to 140V, 40μA no-load quiescent current, and 0.8V precision reference. It enables 100% duty cycle operation via integrated charge pump and supports programmable gate drive (5–10V) for optimized FET selection in industrial power supplies.

For engineers reviewing the LTC3895HFE#PBF datasheet, LTC3895HFE#PBF pinout, LTC3895HFE#PBF application, or LTC3895HFE#PBF equivalent, key selection criteria include its –40°C to 150°C junction temperature rating, phase-lockable 75–850kHz switching frequency, OPTI-LOOP® compensation for wide output capacitor/ESR tolerance, and dual LDO options (VIN-, EXTVCC-, or NDRV-based) for DRVCC regulation.

Technical Context

The LTC3895HFE#PBF implements a constant-frequency current-mode architecture with internal transconductance error amplifier (gm = 2.2 mmho), programmable current limit thresholds (50/75/100 mV), and selectable light-load modes (Burst Mode®, pulse-skipping, or forced continuous). Its gate drivers feature matched rise/fall times (25/15 ns) and dead-time control (50–55 ns) to prevent shoot-through.

It integrates three independent DRVCC supply paths-internal VIN LDO, external NMOS NDRV LDO, and EXTVCC LDO-with switchover thresholds (4.7V or 7.7V) set by DRVUV. The charge pump (ICPUMP = 55–65 µA) sustains BOOST voltage for high-side driver operation during dropout, enabling true 100% duty cycle when CPUMP_EN = INTVCC.

Key Specifications

Pinout & Package

Package: 38-lead plastic TSSOP (FE package), exposed pad (Pin 39) soldered to PCB ground for thermal and electrical performance. θ_JA = 28°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage synchronous buck controller applications.

Compared with MPQ4333-AEC1 and LTC3891HFE#PBF, the LTC3895HFE#PBF uniquely combines 140V input, 150°C operation, fully programmable gate drive, and multi-source DRVCC - making it the only option for high-reliability, high-input-voltage, externally driven synchronous buck designs requiring thermal headroom and system-level timing coordination.

Availability

LTC3895HFE#PBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive on-board chargers, and telecom rectifier modules requiring stable component supply with extended temperature qualification.

Supply support for LTC3895HFE#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 high-performance analog IC portfolio, emphasizing precision, reliability, and ruggedized operation for demanding applications.

The LTC3895HFE#PBF belongs to Linear's high-voltage DC/DC controller product line, designed specifically for industrial, automotive, and telecom systems requiring wide input ranges, high ambient temperature resilience, and flexible power-stage control.

FAQ

What is the maximum input voltage rating for the LTC3895HFE#PBF?

The LTC3895HFE#PBF has an absolute maximum input voltage rating of 150V and a specified operating input range of 4V to 140V. This makes it suitable for high-voltage battery systems, telecom rectifiers, and industrial power supplies where transient overvoltages must be accommodated without external clamping. The H-grade temperature rating ensures reliable operation even under sustained high-voltage stress at elevated ambient temperatures.

How does the LTC3895HFE#PBF achieve 100% duty cycle operation?

The LTC3895HFE#PBF achieves 100% duty cycle operation using an internal charge pump enabled via the CPUMP_EN pin. When CPUMP_EN is tied to INTVCC, the charge pump generates BOOST voltage above VIN, sustaining gate drive for the top N-MOSFET even when VIN ≈ VOUT. This eliminates the need for an external bootstrap diode and supports dropout-free regulation in high-input, low-output voltage applications.

Can the LTC3895HFE#PBF drive both logic-level and standard MOSFETs?

Yes - the LTC3895HFE#PBF supports programmable gate drive voltage from 5V to 10V via the DRVSET pin. By connecting a resistor (50k–100kΩ) between DRVSET and GND, users can set DRVCC to intermediate voltages (e.g., 6.4V or 7.0V), enabling optimal enhancement of logic-level MOSFETs (low V_GS(th)) while maintaining sufficient overdrive for standard devices - maximizing efficiency across diverse power-stage designs.

What is the purpose of the PHASMD pin on the LTC3895HFE#PBF?

The PHASMD pin on the LTC3895HFE#PBF controls the phase relationship between the CLKOUT signal and the TG gate drive waveform. Pulling PHASMD to GND, INTVCC, or leaving it floating selects 90°, 120°, or 180° phase offset respectively - enabling precise interleaving of multiple LTC3895HFE#PBF controllers in multiphase configurations to reduce input/output ripple and improve thermal distribution.

Does the LTC3895HFE#PBF support synchronization to an external clock source?

Yes - the LTC3895HFE#PBF supports external synchronization via the PLLIN pin, accepting clock signals from 75kHz to 850kHz. When an external clock is applied, the internal phase-locked loop aligns the rising edge of TG with the rising edge of the input clock. This enables deterministic timing across multiple power stages, essential for EMI reduction and coordinated load sharing in polyphase or modular power systems.