Analog Devices Inc. LTC3895HFE#TRPBF

Overview

LTC3895HFE#TRPBF 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 phase-locked frequencies up to 850kHz - used in industrial power supplies requiring wide VIN range and high reliability under thermal stress.

For engineers reviewing the LTC3895HFE#TRPBF datasheet, LTC3895HFE#TRPBF pinout, LTC3895HFE#TRPBF application, or LTC3895HFE#TRPBF equivalent, key selection criteria include its –40°C to 150°C junction temperature rating, programmable gate drive (5V–10V), selectable light-load modes (Burst/Pulse-Skipping/Forced Continuous), and 38-lead TSSOP high-voltage package with exposed thermal pad.

Technical Context

The LTC3895HFE#TRPBF implements a constant-frequency current-mode architecture with dual-loop control: inner current loop using differential SENSE+/SENSE– inputs for accurate peak-current sensing, and outer voltage loop with transconductance error amplifier (gm = 2.2 mmho) and OPTI-LOOP® compensation. Its phase-locked loop (PLLIN) synchronizes switching to external clocks from 75kHz to 850kHz while maintaining tight timing alignment across multi-phase systems.

It integrates three independent LDO paths for DRVCC: internal VIN-based (5.6–6.2V), external NMOS NDRV-based (9.6–10.4V), and EXTVCC-based (5.8–6.2V), with switchover thresholds configurable via DRVUV pin. The top-gate driver uses an internal charge pump (ICPUMP = 55–65µA) enabling 100% duty cycle; the bootstrap diode is eliminated by an integrated switch in the BOOST path.

Key Specifications

Pinout & Package

Package: 38-lead plastic TSSOP (FE package), exposed pad (Pin 39) soldered to PCB ground for thermal and electrical performance (θJA = 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 LTC3895IFE#TRPBF and MPQ4333HG-AEC1-P, the LTC3895HFE#TRPBF uniquely combines 150°C operation, full programmability (frequency, gate drive, light-load mode), and triple-source DRVCC regulation - making it optimal for thermally constrained, high-reliability industrial systems requiring design flexibility.

Availability

LTC3895HFE#TRPBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive ADAS modules, telecom rectifier shelves, and high-voltage battery backup systems requiring stable component supply across extended temperature and long product lifecycles.

Supply support for LTC3895HFE#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 acquired Linear Technology in 2017 and maintains its high-performance analog and power management portfolio with rigorous qualification standards.

The LTC3895HFE#TRPBF belongs to Linear's high-voltage DC/DC controller family designed for ruggedized industrial, automotive, and telecom power conversion where input transients, thermal stress, and long-term reliability are critical.

FAQ

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

The LTC3895HFE#TRPBF has an absolute maximum input supply voltage (VIN) of 150V, with guaranteed operation up to 140V across its full –40°C to 150°C junction temperature range. This rating applies to both continuous operation and transient conditions, making it suitable for applications exposed to load dump or lightning-induced surges in industrial and automotive environments. The device includes internal protection circuitry to withstand these stresses without latch-up or degradation.

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

The LTC3895HFE#TRPBF achieves 100% duty cycle operation through its integrated charge pump circuit enabled by the CPUMP_EN pin. When CPUMP_EN is tied to INTVCC, the internal charge pump generates a boosted voltage for the top gate driver, allowing TG to remain high even when VIN approaches VOUT. This eliminates dropout in low-VIN scenarios such as cold-crank conditions in automotive systems. The charge pump delivers up to 65µA output current and supports full regulation down to VIN = VOUT.

Can the LTC3895HFE#TRPBF be synchronized to an external clock source?

Yes, the LTC3895HFE#TRPBF 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 the TG signal to the rising edge of the input clock. Synchronization remains active regardless of MODE pin setting (Burst, Pulse-Skipping, or Forced Continuous), ensuring deterministic timing in multi-phase or noise-sensitive systems without requiring additional timing ICs.

What are the options for powering the DRVCC supply in the LTC3895HFE#TRPBF?

The LTC3895HFE#TRPBF offers three independent DRVCC power sources: (1) internal VIN-based LDO (5.6–6.2V), (2) external NMOS NDRV-based LDO (9.6–10.4V), and (3) EXTVCC-based LDO (5.8–6.2V). Selection is automatic based on voltage levels and configured via DRVUV pin. This redundancy ensures robust gate drive under varying input conditions - for example, EXTVCC takes over during high-VIN operation to reduce power dissipation, while NDRV enables ultra-low dropout performance in battery-fed systems.

Does the LTC3895HFE#TRPBF support fixed output voltages without external resistors?

Yes, the LTC3895HFE#TRPBF supports pin-programmed fixed outputs of 5V or 3.3V without external feedback resistors. This is achieved by tying the VPRG pin to INTVCC (for 5V) or GND (for 3.3V), which activates internal resistor dividers that regulate VFB to the corresponding reference. Floating VPRG enables adjustable operation from 0.8V to 60V using external resistors. All configurations maintain the same 0.8V reference accuracy and load/line regulation specs, ensuring consistent performance across modes.