Analog Devices Inc. LTC3634MPFE#TRPBF

Overview

LTC3634MPFE#TRPBF from Analog Devices (formerly Linear Technology) is a high-efficiency, dual-channel monolithic synchronous step-down regulator optimized for DDR1/DDR2/DDR3 memory power supplies. It delivers ±3A per channel across 3.6V–15V input, supports 180° out-of-phase operation to reduce input ripple, and provides tightly regulated VDDQ (0.6V–3V) and bidirectional VTT (±3A at 0.9V) rails with VTTR reference buffer (±10mA, ±1.6% accuracy at 0.75V). It is deployed in server memory modules and industrial DDR controllers requiring robust thermal performance.

For engineers reviewing the LTC3634MPFE#TRPBF datasheet, LTC3634MPFE#TRPBF pinout, LTC3634MPFE#TRPBF application, or LTC3634MPFE#TRPBF equivalent, this page delivers verified specifications, validated pin functions, confirmed DDR-specific timing architecture, and real-world design context for point-of-load DDR power delivery under –55°C to 150°C extended temperature operation.

Technical Context

The LTC3634MPFE#TRPBF implements current-mode control with controlled on-time architecture, enabling stable high-frequency operation (500kHz–4MHz) from 12V input while maintaining low duty-cycle regulation for DDR VDDQ. Its dual independent channels feature programmable phase shift (90°/180°), external synchronization via MODE/SYNC, and separate VIN1/VIN2 inputs for flexible power domain partitioning.

Channel 1 uses an internal 0.6V reference and supports Burst Mode® for light-load efficiency; Channel 2 references VTTR = VDDQIN × 0.5 and operates in forced continuous mode only. VTTR is buffered (±10mA, 0.01µF capacitive load capability) and serves as both VTT regulation reference and DDR VREF source.

Key Specifications

Pinout & Package

Package: 28-lead plastic TSSOP with exposed PGND pad (θ_JA = 25°C/W); pin-compatible with QFN variant but distinct lead frame layout and thermal path.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel DDR power supply applications.

Compared with LTC3634MPFE#TRPBF, TPS51200DRCR requires external circuitry to replicate VDDQ+VTTR functionality, while LTC3633AEUFD#TRPBF lacks DDR-specific features entirely-making LTC3634MPFE#TRPBF uniquely suited for integrated DDR memory power where rail coupling, reference buffering, and phase interleaving are mandatory.

Availability

LTC3634MPFE#TRPBF is available at Aetrix Electronics and suitable for DDR memory power supplies, industrial server memory modules, and aerospace onboard computer systems requiring stable component supply across extended temperature ranges.

Supply support for LTC3634MPFE#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 analog and power management product lines with rigorous military- and aerospace-grade qualification processes.

The LTC3634MPFE#TRPBF belongs to Linear's DDR-specific power management family, engineered to replace discrete solutions with integrated VDDQ/VTT generation, VTTR reference buffering, and thermally robust packaging for mission-critical memory subsystems.

FAQ

What is the maximum supported switching frequency for LTC3634MPFE#TRPBF?

The LTC3634MPFE#TRPBF supports a programmable switching frequency range of 500kHz to 4MHz, set by an external resistor on the RT pin. At RT = 80.6kΩ, it achieves 2MHz; at RT = 162kΩ, it operates at 1.4MHz. The upper limit of 4MHz enables use of sub-1µH inductors in space-constrained DDR designs while maintaining stability and efficiency.

Does LTC3634MPFE#TRPBF support independent enable control for each channel?

Yes, LTC3634MPFE#TRPBF provides fully independent enable control via RUN1 (Pin 3) and RUN2 (Pin 6). Each pin activates its respective channel when driven above 1.22V and places it in shutdown below 1.01V. This allows precise power sequencing-for example, enabling VDDQ before VTT in DDR initialization-and supports dynamic rail disabling during low-power states.

How does the VTTR output function in LTC3634MPFE#TRPBF?

The VTTR pin (Pin 21) in LTC3634MPFE#TRPBF outputs a buffered voltage equal to VDDQIN × 0.5, with ±1.6% accuracy at 0.75V and ±10mA drive capability. It serves dual roles: as the feedback reference for Channel 2 (VTT regulation) and as the DDR VREF supply. Its low-noise, capacitive-load-tolerant design eliminates external op-amps in compliant DDR implementations.

What thermal advantages does the TSSOP package of LTC3634MPFE#TRPBF offer?

The LTC3634MPFE#TRPBF in 28-lead TSSOP (FE package) features an exposed PGND pad and θ_JA = 25°C/W-significantly lower than the QFN variant's 43°C/W. This enables higher sustained power delivery in convection-cooled environments and simplifies thermal design in legacy PCBs where QFN reflow is impractical, especially under the –55°C to 150°C operating range.

Can LTC3634MPFE#TRPBF operate with different input voltages on VIN1 and VIN2?

Yes, LTC3634MPFE#TRPBF supports independent input supplies: VIN1 (Pins 24,25) powers Channel 1 and the INTVCC LDO, while VIN2 (Pins 18,19) powers Channel 2 only. This allows optimization-e.g., feeding Channel 1 from a clean 5V rail for VDDQ and Channel 2 from a higher-current 12V rail for VTT-without cross-regulation or shared noise coupling.