Analog Devices Inc. LTC3787IUFD#PBF

Overview

LTC3787IUFD#PBF from Analog Devices (formerly Linear Technology) is a dual-phase synchronous boost controller IC driving two N-channel MOSFET stages out-of-phase to reduce input/output capacitance and power supply noise. It supports 4.5V–38V input, up to 60V output, ±1% 1.200V reference, and operates down to 2.5V after startup - ideal for high-power industrial DC-DC boost conversion in battery-powered or wide-input systems.

For engineers reviewing the LTC3787IUFD#PBF datasheet, LTC3787IUFD#PBF pinout, LTC3787IUFD#PBF application, or LTC3787IUFD#PBF equivalent, key selection criteria include phase-lockable frequency (75–850 kHz), RSENSE/DCR current sensing, 100% duty cycle capability, low 135μA quiescent current, and thermal performance in the 4mm × 5mm QFN package with exposed pad.

Technical Context

The LTC3787IUFD#PBF implements constant-frequency current-mode control with two independent channels operating 180° out-of-phase. Its error amplifier compares VFB against a precision 1.200V reference, while ITH sets peak inductor current; internal slope compensation ensures stability across duty cycles.

It integrates a phase-locked loop (PLL) for synchronization, programmable oscillator (50–900 kHz), and three light-load modes (Burst Mode®, pulse-skipping, forced continuous) selected via PLLIN/MODE. The INTVCC LDO (5.4V) powers gate drivers and logic, optionally bypassed by EXTVCC ≥4.8V to reduce thermal load.

Key Specifications

Pinout & Package

Package: 28-lead (4mm × 5mm) plastic QFN with exposed thermal pad (Pin 29 = GND). θJA = 43°C/W enables high-power density without heatsink in thermally constrained PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous boost controller applications.

Compared with LTC3781IUFD#PBF and MP9942GQ-P, the LTC3787IUFD#PBF uniquely delivers dual-phase interleaving, 60V output support, and full programmability - making it the only option for high-reliability, high-power (>10A), wide-input industrial and automotive boost systems requiring EMI control and thermal efficiency.

Availability

LTC3787IUFD#PBF is available at Aetrix Electronics and suitable for industrial motor drives, automotive ADAS power supplies, medical portable imaging, and military ruggedized comms requiring stable component supply, extended temperature operation, and long-term lifecycle assurance.

Supply support for LTC3787IUFD#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 legacy of high-performance analog and power management ICs with rigorous automotive, industrial, and military qualification standards.

The LTC3787IUFD#PBF belongs to Linear's PolyPhase® controller family, designed specifically for high-efficiency, low-EMI, multi-phase DC-DC boost conversion in demanding power systems where thermal density, transient response, and reliability are critical.

FAQ

What is the maximum output voltage supported by the LTC3787IUFD#PBF?

The LTC3787IUFD#PBF supports output voltages up to 60V, enabled by its robust 76V absolute maximum rating on BOOST1/BOOST2 pins and integrated gate drivers capable of sustaining high-side floating bias. This makes LTC3787IUFD#PBF suitable for high-voltage industrial and medical applications such as LED drivers and detector bias supplies where standard 36V controllers fall short.

Does the LTC3787IUFD#PBF support DCR current sensing, and how is it configured?

Yes, the LTC3787IUFD#PBF supports both RSENSE and inductor DCR current sensing. DCR sensing is implemented using the SENSE1+/SENSE1− and SENSE2+/SENSE2− differential inputs, which accept the voltage drop across the inductor's parasitic resistance. A small RC network (typically 100Ω + 1nF) filters the switching noise, and the common-mode range (2.5V–38V) ensures compatibility across the full input range - a key advantage of LTC3787IUFD#PBF over many competing controllers.

How does the LTC3787IUFD#PBF achieve low quiescent current, and what is its shutdown behavior?

The LTC3787IUFD#PBF achieves 135μA quiescent current in pulse-skipping mode and <8μA in full shutdown via the RUN pin. Pulling RUN below 0.7V disables all control loops, gate drivers, and the INTVCC LDO. Its internal 4.5μA RUN pin current source enables resistor-divider hysteresis, and the 11V internal clamp allows direct connection to VIN - features that make LTC3787IUFD#PBF ideal for always-on battery systems requiring ultra-low standby drain.

Can the LTC3787IUFD#PBF be synchronized to an external clock, and what is the valid frequency range?

Yes, the LTC3787IUFD#PBF can be synchronized to an external clock applied to the PLLIN/MODE pin. The internal phase-locked loop locks to input frequencies from 75kHz to 850kHz, ensuring deterministic timing alignment across multiple phases or with system clocks. This capability is essential for EMI reduction in dense PCB layouts and deterministic timing in time-sensitive applications - a distinguishing feature of LTC3787IUFD#PBF versus fixed-frequency alternatives.

What thermal considerations apply to the LTC3787IUFD#PBF in the 4mm × 5mm QFN package?

The LTC3787IUFD#PBF in the UFD package has θJA = 43°C/W when the exposed pad (Pin 29) is properly soldered to a minimum 200mm² PCB copper pour. Junction temperature must remain ≤125°C for industrial-grade operation; at 10A/24V output, typical power dissipation is ~1.2W, requiring ≥4cm² thermal pad area. Unlike SSOP variants (θJA = 90°C/W), the QFN package enables higher power density - a critical design advantage of LTC3787IUFD#PBF in space-constrained applications.