ADI 50-A µModule regulator sports outboard inductors as heat sinks

By Brian Santo, contributing writer

Analog Devices Inc. (ADI) has been expanding its line of micromodule (µModule) regulators, introducing more than a half-dozen new models this year. Its latest has a unique twist, though: The inductors of the LTM4678 are exposed on the surface of the BGA so that they’ll do double duty as heat sinks.

In April, the company announced a particularly small, low-power module: the LTM4661 . This module is a step-up regulator that integrates only a few capacitors and a single resistor. It occupies less than 1 cm² single-sided or 0.5 cm² on double-sided PCBs. ADI has also begun marketing a set of other µModules in various configurations.

The new Power by Linear LTM4678 step-down µModule regulator is integrated with a PMBus digital interface, designed for digital management of power supplies.

By stacking and exposing its two inductors on top of the BGA package, the LTM4678 uses the inductors as heat sinks to transfer heat from inside, keeping the device cool. On-board EEPROM and PMBus I² C enables a user to measure, alter, and record parameters including voltage, load current, temperature, and sequencing, said ADI.

Applications include PCIe boards, communication infrastructure, cloud computing, and optical as well as medical, industrial, and test and measurement devices.

The LTM4678 comes in two configurations: dual 25 A or single 50 A. ADI said that designers can group up to five of the devices; they will current-share at 50 A each to deliver up to 250 A to loads such as processors, FPGAs, and ASICs.

The LTM4678 integrates a DC/DC controller, EEPROM, power FETs, inductors, and supporting components in a 16 × 16 × 5.86-mm BGA package. ADI said that it guarantees output voltage accuracy of ±0.5% over line, load, and temperature (−40°C to 125°C).

The LTM4678 operates from 4.5-V to 16-V input range, and the two output voltages are digitally controlled from 0.5 V to 3.3 V. The switching frequency is 350 kHz to 1 MHz and can be synchronized to an external clock from 350 kHz to 1 MHz for noise-sensitive applications.

Available now, pricing starts at $47.48 in quantities of 1,000.