Analog Devices Inc. LTC3633AIUFD-1#TRPBF

Overview

LTC3633AIUFD-1#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic synchronous step-down regulator delivering 3A per channel across a 3.6V–20V input range. It features controlled on-time current-mode architecture, 180° phase-shift capability between channels, adjustable 500kHz–4MHz switching frequency, and supports both Burst Mode® and forced continuous operation. It is used in high-density point-of-load power supplies for FPGA, ASIC, and DSP core voltage regulation.

For engineers reviewing the LTC3633AIUFD-1#TRPBF datasheet, LTC3633AIUFD-1#TRPBF pinout, LTC3633AIUFD-1#TRPBF application, or LTC3633AIUFD-1#TRPBF equivalent, key selection criteria include its VON sense range (1.5V–12V), dual-channel interleaved operation, ±8% PGOOD threshold, 0.6V internal reference, and QFN-28 (4mm × 5mm) package with exposed PGND pad.

Technical Context

The LTC3633AIUFD-1#TRPBF implements a constant-frequency, controlled on-time current-mode control architecture with an internal PLL that locks switch timing to either the internal oscillator or an external clock applied to MODE/SYNC. Its two independent buck channels support 180° out-of-phase operation via PHMODE pin control, reducing RMS input current and relaxing input capacitance requirements.

Each channel uses internal N-channel MOSFETs (130mΩ top / 65mΩ bottom), supports output voltage tracking and soft-start via TRACKSS pins, and provides independent RUN enable, PGOOD status, and ITH compensation interfaces. The device distinguishes itself from the base LTC3633A by its extended VON sense range (1.5V–12V vs. 0.6V–6V), enabling stable regulation at higher output voltages without external scaling.

Key Specifications

Pinout & Package

Package: 28-lead (4mm × 5mm) plastic QFN with exposed PGND pad (Pin 29), rated for –40°C to +125°C junction temperature. Exposed pad must be soldered to PCB for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel synchronous buck regulator applications.

Compared with LTC3633AEUFD-1#TRPBF, the LTC3633AIUFD-1#TRPBF offers identical performance with industrial-grade finish; compared with TPS543B20RTWR, it delivers true dual-channel integration with hardware-based interleaving and zero software dependency - reducing BOM count and startup complexity.

Availability

LTC3633AIUFD-1#TRPBF is available at Aetrix Electronics and suitable for industrial PLCs, medical imaging sensors, automotive ADAS camera ECUs, and test & measurement FPGA boards requiring stable component supply with guaranteed long-term availability.

Supply support for LTC3633AIUFD-1#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and automotive markets.

The LTC3633A family was designed for high-density, high-efficiency dual-rail point-of-load regulation in space-constrained systems where thermal performance, transient response, and analog control simplicity are critical - especially in FPGA, ASIC, and sensor subsystems.

FAQ

What is the VON sense range for LTC3633AIUFD-1#TRPBF?

The LTC3633AIUFD-1#TRPBF has a VON sense range of 1.5V to 12V, distinguishing it from the base LTC3633A (0.6V–6V). This allows direct connection of VON1/VON2 to higher output rails like 3.3V, 5V, or 12V without external resistive scaling, preserving on-time accuracy and minimizing component count in multi-rail designs.

How does phase-shift operation reduce input capacitance requirements for LTC3633AIUFD-1#TRPBF?

When LTC3633AIUFD-1#TRPBF operates with 180° phase shift (PHMODE = INTVCC), the input current pulses from each channel are interleaved. This cuts peak-to-peak input ripple current by up to 50% versus in-phase operation, allowing use of fewer or smaller ceramic input capacitors - typically reducing total CIN by 30–40% while maintaining equivalent RMS current rating.

Can LTC3633AIUFD-1#TRPBF synchronize to an external clock, and what happens to operating mode?

Yes - applying a clock signal to the MODE/SYNC pin synchronizes LTC3633AIUFD-1#TRPBF's switching frequency to that source. Critically, this action automatically forces continuous conduction mode regardless of MODE/SYNC DC bias, ensuring deterministic timing for EMI-sensitive or time-critical applications such as high-speed data acquisition systems.

What is the purpose of the TRACKSS pins on LTC3633AIUFD-1#TRPBF?

The TRACKSS1 and TRACKSS2 pins on LTC3633AIUFD-1#TRPBF enable output voltage tracking and soft-start. Applying a voltage <0.6V (e.g., from another regulator's output) causes the LTC3633AIUFD-1#TRPBF to servo its VFB pin to match that voltage. An internal 1.4µA pull-up current allows soft-start by connecting a capacitor from TRACKSS to SGND - generating a linear ramp at the FB node.

Does LTC3633AIUFD-1#TRPBF provide overvoltage protection on its input pins?

Yes - LTC3633AIUFD-1#TRPBF includes dedicated VIN overvoltage lockout circuitry per channel. When VIN rises above 22.5V (rising threshold), both power MOSFETs shut off immediately. Operation resumes only after VIN falls below 21.5V (falling threshold), and the device executes a full soft-start sequence upon recovery - protecting downstream components during automotive load-dump or industrial surge events.