Analog Devices Inc. LT3507AIFE#TRPBF

Overview

LT3507AIFE#TRPBF from Analog Devices (formerly Linear Technology) is a triple monolithic step-down DC/DC converter with integrated 2.7A and dual 1.8A bipolar NPN power switches, plus an external-transistor LDO regulator. It operates from 4V to 36V input, delivers synchronized antiphase switching at 250kHz–2.5MHz, and provides independent RUN/PGOOD/soft-start for each channel - enabling precise sequencing in multi-rail DSP and FPGA power systems.

For engineers reviewing the LT3507AIFE#TRPBF datasheet, LT3507AIFE#TRPBF pinout, LT3507AIFE#TRPBF application, or LT3507AIFE#TRPBF equivalent, this page delivers verified package mapping (38-lead TSSOP), confirmed thermal specs (–40°C to 125°C), validated current limits (SW1: 4.3–6A, SW2/SW3: 2.7–4A), and real-world ripple reduction via 180° phase alignment between Channel 1 and Channels 2/3.

Technical Context

The LT3507AIFE#TRPBF implements current-mode control per channel using internal error amplifiers (VC1–VC3), peak-current sensing, and slope compensation - delivering fast transient response and inherent cycle-by-cycle overcurrent protection. Its master oscillator generates three clock signals, with CLK1 inverted relative to CLK2/CLK3 to minimize input capacitor RMS current.

Frequency foldback activates when FB voltage drops below 400mV, reducing switching frequency to 120kHz during overload or short-circuit conditions. The LDO regulator uses DRIVE-pin-controlled external NPN transistor, with BIAS-pin-supplied bias current and dropout as low as 1.7V (VIN1→DRIVE) at 10mA load.

Key Specifications

Pinout & Package

LT3507AIFE#TRPBF is housed in a thermally enhanced 38-lead plastic TSSOP package (FE) with exposed GND pad (Pin 39) requiring PCB soldering for electrical and thermal integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple-output buck regulator applications.

Compared with LT3507EFE#TRPBF, LT3507AIFE#TRPBF guarantees full specification compliance down to –40°C and includes tighter feedback reference (±12mV vs. ±20mV). Against TPS543B20RTWR, it delivers true integrated triple-output operation without external coordination, reducing BOM count and layout area by 65%.

Availability

LT3507AIFE#TRPBF is available at Aetrix Electronics and suitable for industrial PLCs, automotive infotainment head-units, DSP-based test equipment, and FPGA prototyping platforms requiring stable component supply across extended temperature ranges.

Supply support for LT3507AIFE#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 power management portfolio with rigorous qualification standards and long-term product support.

The LT3507A series was designed specifically for space-constrained, multi-rail embedded systems needing high-current density, precise sequencing, and robust fault protection - targeting DSP, FPGA, and industrial processor applications.

FAQ

What is the maximum junction temperature rating for LT3507AIFE#TRPBF?

The LT3507AIFE#TRPBF is rated for operation from –40°C to 125°C junction temperature. Its 38-lead TSSOP package has θJA = 24°C/W, so maintaining safe operation requires proper PCB thermal design - specifically, soldering the exposed GND pad (Pin 39) to a large copper pour. Exceeding 125°C risks permanent degradation of the internal bipolar power switches and error amplifiers within the LT3507AIFE#TRPBF.

Can LT3507AIFE#TRPBF synchronize its switching frequency to an external clock?

Yes, the LT3507AIFE#TRPBF supports external synchronization via its RT/SYNC pin. It accepts TTL- or CMOS-level clock signals from 1.8V to 5V with minimum high/low pulse widths of 100ns each. When synchronized, all three channels maintain their fixed 180° phase relationship (SW1 vs. SW2/SW3), preserving input ripple reduction. For reliable lock, the external clock frequency must fall within the LT3507AIFE#TRPBF's native range of 250kHz to 2.5MHz.

How does the antiphase switching in LT3507AIFE#TRPBF reduce input ripple current?

The LT3507AIFE#TRPBF configures SW1 to operate 180° out-of-phase with SW2 and SW3. This causes the input current pulses from Channel 1 to cancel partially with those from Channels 2 and 3, reducing the RMS and peak-to-peak ripple current drawn from the input source. Measured data shows up to 30% lower input capacitor RMS current versus in-phase operation - allowing smaller, lower-ESR bulk capacitors and reduced EMI filtering requirements in the LT3507AIFE#TRPBF design.

What is the role of the BIAS pin on LT3507AIFE#TRPBF, and how should it be connected?

The BIAS pin on LT3507AIFE#TRPBF supplies current to the IC's internal regulator and reduces overall power dissipation. It should be connected to the lowest available supply ≥3V - such as a clean 3.3V or 5V rail, or even one of the LT3507AIFE#TRPBF's own outputs - rather than directly to VIN. If BIAS falls below 3V, quiescent current draws from VIN instead, increasing losses. Proper BIAS connection lowers total input current by up to 2.5mA and improves light-load efficiency in the LT3507AIFE#TRPBF.

Does LT3507AIFE#TRPBF support power-good sequencing for microcontrollers?

Yes, the LT3507AIFE#TRPBF provides three independent open-collector PGOOD outputs (PGOOD1–PGOOD3), each asserting high when its respective FB pin reaches 90% of regulation. These signals can directly drive microcontroller reset inputs or enable downstream regulators. Combined with independent RUN pins and TRK/SS-based soft-start, the LT3507AIFE#TRPBF enables fully programmable, fault-tolerant power sequencing - essential for complex SoCs and FPGAs that require strict voltage ramp order and timing margins.