LTM4644IY#PBF Datasheet, Pinout, Equivalents, and Specs

The LTM4644IY#PBF is a quad-output DC/DC step-down µModule (micromodule) regulator developed by Analog Devices. It integrates switching controllers, power FETs, inductors, and supporting components into a single surface-mount BGA package. This high level of integration provides a complete power solution designed to simplify and accelerate the design of complex, multi-rail power systems for high-density applications.

What is the LTM4644IY#PBF?

The LTM4644IY#PBF is a complete System-in-Package (SiP) power management solution. Internally, it contains four independent synchronous step-down switching regulator channels, each capable of delivering up to 4A of continuous output current. The device's architecture is engineered to minimize external component count and reduce the design complexity associated with discrete power supply implementations. Its primary engineering benefit is the significant reduction in required PCB area, improved thermal performance, and minimized electromagnetic interference (EMI) due to the shielded, integrated inductors. The target market includes designers of telecom infrastructure, industrial automation, and high-performance computing systems that utilize FPGAs, ASICs, and processors requiring multiple low-voltage, high-current power rails.

Pinout Configuration and Packaging

The LTM4644IY#PBF is offered in a 9mm × 15mm × 4.92mm BGA (Ball Grid Array) package. This package format is critical for both space savings and thermal management, as it allows heat to be dissipated directly into the PCB through the solder ball array. Key pins include the main input voltage (VIN), the four independent output voltage pins (VOUT1-VOUT4), associated feedback pins (FB1-FB4), and control signals such as RUN and PGOOD for each channel. The BGA pinout requires careful PCB layout and advanced assembly processes, but provides superior electrical and thermal performance compared to leaded packages.

Core Architectural Features

• Quad 4A Outputs with PolyPhase Current Sharing: The device features four independent DC/DC converter channels, each rated for 4A. For higher current requirements, these channels can be paralleled to create a single output of 8A, 12A, or up to 16A. This current sharing capability is configured with minimal external components, providing significant design flexibility for various load requirements.
• Wide Operating Voltage Ranges: The LTM4644IY#PBF operates from an input voltage range of 4V to 14V, or down to 2.375V with an external bias supply. The output voltages are user-adjustable from 0.6V to 5.5V, accommodating a wide variety of digital logic core, memory, and I/O voltage levels.
• Integrated Power Stage and Magnetics: The complete integration of power MOSFETs and inductors within the package eliminates the complex tasks of component selection, loop compensation, and layout optimization. This reduces design risk and time-to-market while also minimizing high-frequency switching noise and EMI.
• Advanced Control and Protection Features: Each channel includes selectable Burst Mode® operation for high efficiency at light loads or forced continuous conduction mode for low-noise performance. The module also provides comprehensive protection, including output overvoltage protection, overcurrent protection, and thermal shutdown. Independent tracking/soft-start and power good (PGOOD) indicators allow for reliable power sequencing in complex systems.

Specifications Parameter Table

LTM4644IY#PBF Equivalents, Cross Reference, and Lifecycle

The LTM4644IY#PBF is currently in "Active" production status. Due to the highly integrated and proprietary nature of µModule regulators, finding a direct pin-to-pin compatible, drop-in replacement from a competing manufacturer is generally not feasible. The BGA footprint and internal architecture are specific to Analog Devices. When sourcing alternatives due to allocation or long lead times, engineers should first consider other parts within the LTM464x family. For example, the LTM4644-1 offers similar functionality with different default settings. Any potential replacement, even within the same family, requires careful review of the datasheet to verify differences in electrical characteristics, pin functions, and thermal performance. Functional alternatives from other manufacturers, such as the Texas Instruments TPSM series or MPS MPM series, would necessitate a complete PCB redesign.

Typical Application & Circuit Considerations

The LTM4644IY#PBF is typically used to power multi-rail systems such as FPGAs, ASICs, and embedded computing platforms. A typical application circuit requires minimal external components: input and output bulk capacitors and small ceramic capacitors for each channel, along with feedback resistors to set the output voltages. For optimal performance, low ESR ceramic capacitors should be placed as close as possible to the BGA pins. PCB layout is critical; a large, unbroken ground plane directly beneath the module is essential for thermal dissipation and to provide a low-inductance return path for switching currents. Feedback traces should be routed away from noisy switch nodes (PH pins) to prevent noise coupling and ensure stable regulation.

Video Demonstration

Market Availability and Pricing Trends

High-performance, integrated power modules

Alan Carter

Senior Hardware Engineer & Component Specialist

Alan has over 15 years of expertise in embedded systems design, FPGA architecture, and global semiconductor supply chains. He specializes in component cross-referencing, lifecycle management, and helping OEMs navigate supply shortages.