Analog Devices Inc. LTC4444IMS8E-5#PBF

Overview

LTC4444IMS8E-5#PBF from Analog Devices (formerly Linear Technology) is a high-frequency, high-voltage synchronous N-channel MOSFET gate driver IC designed for buck and buck-boost DC/DC converters. It drives both high-side and low-side N-MOSFETs with 1.4A peak top-gate pull-up, 1.75A peak bottom-gate pull-up, adaptive shoot-through protection, and operates with VCC from 4.5V to 13.5V and bootstrapped supply up to 114V above ground. It enables high-efficiency power conversion in automotive and telecom power modules.

For engineers reviewing the LTC4444IMS8E-5#PBF datasheet, LTC4444IMS8E-5#PBF pinout, LTC4444IMS8E-5#PBF application, or LTC4444IMS8E-5#PBF equivalent, key selection criteria include bootstrap voltage tolerance (up to 114V), dual independent inputs with internal level-shifting, undervoltage lockout thresholds (3.55V falling), thermal performance in MS8E package, and timing parameters for high-frequency switching up to 1MHz.

Technical Context

The LTC4444IMS8E-5#PBF integrates CMOS-compatible input buffers with 450mV hysteresis and independent threshold referencing (VIH = 2.75V, VIL = 2.3V), enabling noise-immune control of external MOSFETs. Its output stage uses bipolar NPN pull-up transistors and N-channel MOSFET pull-down devices-RDS(TG) = 1.5Ω typ, RDS(BG) = 0.75Ω typ-to deliver fast transitions (tf(TG) = 5ns, tf(BG) = 3ns @ 1nF).

Adaptive shoot-through protection monitors TS voltage and input timing to prevent simultaneous conduction: if BINP remains high when TINP rises, TG is delayed until BG falls; if TS stays high after TINP turns off, BG activates after 150ns. Undervoltage lockout disables outputs when VCC drops below 3.55V, pulling TG to TS and BG to GND.

Key Specifications

Pinout & Package

Package: 8-lead plastic MSOP (MS8E) with thermally enhanced exposed pad (Pin 9 = GND). Requires soldering of exposed pad to PCB ground for θJA = 40°C/W; unsoldered pad degrades thermal performance significantly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC4446 and LTC4440-5, the LTC4444IMS8E-5#PBF uniquely combines dual N-MOSFET drive, 114V bootstrap, and adaptive shoot-through in one MS8E package-making it optimal for compact, high-reliability synchronous buck designs where integrated timing safety is mandatory.

Availability

LTC4444IMS8E-5#PBF is available at Aetrix Electronics and suitable for automotive power supplies, telecommunication systems, and high-density power modules requiring stable component supply across extended temperature ranges (–40°C to 125°C).

Supply support for LTC4444IMS8E-5#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 precision analog and power management portfolio. Linear Technology was founded in 1981 and specialized in high-performance linear ICs, known for innovation in power conversion and signal conditioning.

The LTC4444IMS8E-5#PBF belongs to Linear's high-voltage gate driver product line, engineered specifically for synchronous DC/DC converters demanding robust shoot-through immunity, wide input voltage range, and fast switching in harsh environments.

FAQ

What is the maximum allowable voltage on the BOOST pin relative to TS for LTC4444IMS8E-5#PBF?

The absolute maximum BOOST–TS voltage for LTC4444IMS8E-5#PBF is 114V, as specified in the Absolute Maximum Ratings table. This defines the upper limit of the bootstrapped high-side supply swing and enables reliable operation with input voltages up to 100V. Exceeding 114V risks permanent damage. The LTC4444IMS8E-5#PBF achieves this rating through internal level-shifting and isolation design, distinguishing it from drivers with lower bootstrap limits like the LTC4440-5 (80V max).

Does LTC4444IMS8E-5#PBF require external bootstrap diodes, and what are the key selection criteria?

Yes, LTC4444IMS8E-5#PBF requires an external bootstrap diode connected between VCC (Pin 3) and BOOST (Pin 6). Key selection criteria include low forward voltage (to maximize BOOST voltage), fast recovery (to minimize reverse recovery charge), and sufficient current rating (≥10mA average). Schottky diodes such as Diodes Inc. B1100-13-F are commonly used. The LTC4444IMS8E-5#PBF datasheet specifies that V_D directly impacts BOOST voltage headroom and thus high-side gate drive strength.

How does the adaptive shoot-through protection in LTC4444IMS8E-5#PBF differ from fixed dead-time schemes?

LTC4444IMS8E-5#PBF's adaptive shoot-through protection dynamically delays TG activation based on real-time TS voltage and BINP state-unlike fixed dead-time, which inserts static delays regardless of actual MOSFET turn-off speed. If BG remains high when TINP rises, TG waits until BG falls; if TS stays high post-TINP-off, BG activates after 150ns. This eliminates unnecessary delay while guaranteeing zero cross-conduction. The LTC4444IMS8E-5#PBF implements this entirely internally, requiring no external timing components.

What is the role of Pin 9 (exposed pad) in LTC4444IMS8E-5#PBF, and why is soldering mandatory?

Pin 9 is the exposed thermal pad of the LTC4444IMS8E-5#PBF MS8E package and serves as the primary thermal and electrical ground path. It must be soldered to a PCB ground plane to achieve the specified θJA of 40°C/W; unsoldered or poorly soldered pads increase thermal resistance beyond 100°C/W, risking thermal shutdown or premature failure. The LTC4444IMS8E-5#PBF datasheet explicitly states that failure to solder the pad results in "a thermal resistance much higher than 40°C/W" and degrades long-term reliability.

Can LTC4444IMS8E-5#PBF drive MOSFETs with gate charges exceeding 100nC?

Yes, LTC4444IMS8E-5#PBF can drive high-Q_G MOSFETs: its 1.4A peak TG pull-up and 1.75A peak BG pull-up currents enable efficient charging of gates with Q_G > 100nC at typical switching frequencies (e.g., 500kHz). Gate charge loss is calculated as P_QG = 2 × V_CC × Q_G × f_IN; for Q_G = 120nC, V_CC = 12V, f_IN = 500kHz, P_QG ≈ 14.4mW - well within LTC4444IMS8E-5#PBF's thermal budget when the exposed pad is properly soldered.