Analog Devices Inc. LT3587EUD#TRPBF

Overview

LT3587EUD#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage monolithic inverter and dual-boost DC/DC converter IC designed for compact, multi-rail bias generation in portable imaging and display systems. It delivers three regulated outputs - +15V @ 50mA (Boost1), –8V @ 100mA (Inverter), and +15V @ 20mA (Boost3) - from a single 2.5V–6V Li-ion input, with integrated power switches, soft-start sequencing, and output disconnect MOSFETs.

For engineers reviewing the LT3587EUD#TRPBF datasheet, LT3587EUD#TRPBF pinout, LT3587EUD#TRPBF application, or LT3587EUD#TRPBF equivalent, key selection considerations include its triple-output topology, programmable Boost3 current/voltage regulation, fault-latched FLT pin behavior, and 20-pin 3mm × 3mm QFN package with exposed thermal pad.

Technical Context

The LT3587EUD#TRPBF integrates three independent current-mode PWM controllers: two boost regulators (Boost1 and Boost3) and one inverting regulator, all operating at a fixed 1MHz switching frequency. Each channel features dedicated feedback references (1.22V for Boost1, 0.8V for Boost3, ground-referenced for inverter), internal soft-start ramp generators, and output disconnect PMOS transistors (R_DISC1 = 5–8Ω, R_DISC3 = 10–15Ω).

Sequencing is hardware-controlled: Boost1 enables first, then the inverter activates only after Boost1 reaches ≥87% of regulation; Boost3 operates independently via EN/SS3. Fault detection monitors all enabled outputs continuously, asserting the open-drain FLT pin low after 16ms of regulation loss - latching until EN/SS pins are cycled or VIN is recycled.

Key Specifications

Pinout & Package

LT3587EUD#TRPBF is housed in a 20-lead plastic QFN package (3mm × 3mm, 0.5mm pitch) with an exposed thermal pad (Pin 21) that must be soldered to PCB ground. Pin functions are electrically isolated per channel and validated per Linear Technology's official pinout documentation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-output high-voltage DC/DC converter applications.

Compared with LTC3589-2 and MAX17710, the LT3587EUD#TRPBF uniquely integrates an inverter alongside dual boost regulators in a single 3mm × 3mm QFN, making it the only option among the three capable of generating matched +15V/–8V rails without external inverter stages or complex sequencing ICs.

Availability

LT3587EUD#TRPBF is available at Aetrix Electronics and suitable for CCD imager bias, white LED backlighting, and OLED display driver applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LT3587EUD#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 full product support, datasheets, and application notes for the LT3587EUD#TRPBF under the Linear brand legacy.

The LT3587EUD#TRPBF belongs to Linear's high-voltage DC/DC converter product line, engineered specifically for portable imaging, medical sensing, and display systems demanding compact, multi-rail, battery-efficient bias generation.

FAQ

What is the maximum output voltage capability of the LT3587EUD#TRPBF?

The LT3587EUD#TRPBF supports up to +32V on its Boost1 and Boost3 outputs and up to –32V on its inverter output. The CAP3 pin includes an internal overvoltage clamp that disables SW3 switching if voltage exceeds 27–31V, protecting downstream components. These ratings are specified in the Absolute Maximum Ratings table and confirmed across the –40°C to 125°C junction temperature range.

How does the LT3587EUD#TRPBF implement output sequencing between Boost1 and the inverter?

The LT3587EUD#TRPBF uses internal hardware sequencing: the inverter remains disabled until the Boost1 output reaches ≥87% of its final regulated value, as verified by FB1 feedback monitoring. This behavior is intrinsic to the IC's block diagram and does not require external timing components. Sequencing ensures stable startup and prevents cross-regulation issues in sensitive imaging circuits.

Can the LT3587EUD#TRPBF operate Boost3 as both a voltage regulator and a current regulator?

Yes - the LT3587EUD#TRPBF's Boost3 channel selects regulation mode based on feedback priority: if the voltage at VFB3 exceeds that at IFB3, it regulates output voltage (e.g., 15V); if IFB3 voltage dominates, it regulates output current (e.g., 20mA). This dual-mode capability is implemented in silicon and documented in the Operation section of the datasheet.

What is the function of the FLT pin on the LT3587EUD#TRPBF, and how does it behave during fault conditions?

The FLT pin on the LT3587EUD#TRPBF is a bidirectional open-drain fault indicator that pulls low when any enabled output remains out of regulation for more than 16ms. Once asserted, FLT latches low until either EN/SS1 and EN/SS3 are pulled below 0.2V or VIN is cycled - ensuring persistent fault signaling without software polling.

Is the exposed thermal pad (Pin 21) on the LT3587EUD#TRPBF required to be connected to ground?

Yes - the exposed pad (Pin 21) on the LT3587EUD#TRPBF is electrically connected to GND and must be soldered to the PCB ground plane using multiple thermal vias. This connection is mandatory for both thermal dissipation (θ_JA = 68°C/W) and electrical integrity, as stated in the Absolute Maximum Ratings and Package Description sections.