■ LTM4657, High-Efficiency Step-Down μModule® Device

The LTM4657 is a very small, high-efficiency step-down μModule® device.

The LTM4657 operates at a lower switching frequency than its pinout-equivalent counterparts, the LTM4626 and LTM4638, while achieving excellent efficiency at output currents up to 8A.

The LTM4657 fills the gap between the LTM4626 and LTM4638, combining the high efficiency of the LTM4638 with the low profile of the LTM4626.





The LTM4657 provides up to 8A of continuous output current from an input voltage of 3.1V to 20V.

The LTM4657 uses the same component-on-package design as the LTM4626 and LTM4638, maintaining the compact 6.25mm x 6.25mm footprint while operating at a lower device temperature.

The LTM4626, LTM4638, and LTM4657 are pin-compatible and have the same footprint, allowing users to leverage previously designed layouts and conveniently select the Module device that best suits their application.

The LTM4626, LTM4638, and LTM4657 are step-down solutions featuring industry-leading power density.

The attractive size and high efficiency of these Module products provide flexible turnkey solutions for a wide range of applications.

Minimizes the use of external components required for step-down solutions by integrating the inductor, FET, top feedback resistor, frequency resistor, and optional compensation function internally.

With minimal design, this module technology offers a variety of optional features using a 49-pin BGA package that maximizes pin count.





PGOOD, RUN, TRACK/SS pins etc. In addition to common features, the LTM4657 uses CLKIN, CLKOUT, and PHMODE functions to improve parallel and EMI operation.

Differential remote sensing amplifiers improve output voltage accuracy.

It also includes a temperature sensing pin to protect the internals from overheating.





■ Suitable for applications with high switching loss and low conduction loss

The LTM4657 uses higher value inductors than the LTM4626 or LTM4638. This allows operation at lower frequencies and reduces switching losses.

The LTM4657 is ideal for applications with high switching losses and low conduction losses, such as low load current and high input voltage applications.





Figure 4 compares the efficiency of the LTM4626 and LTM4657 when operating at the same switching frequency with the same configuration on the DC2989A demo board.

This 12V IN 5V OUT configuration clearly demonstrates the LTM4657's advantages in terms of switching losses.

The higher value inductor of the LTM4657 reduces the output voltage ripple. However, the LTM4626 can provide higher load current than the LTM4657.

■ Providing an attractive solution for users seeking low switching loss and high efficiency

The LTM46xx family offers different load currents with the same footprint and pinout.

The LTM4657 enables maximum performance in designs with low load currents.

Along with the LTM4626 and LTM4638, we will continue to add products in this ultra-small footprint family to deliver even more advanced performance.

The LTM4657 provides an attractive solution for users seeking low switching losses and high efficiency at low to medium loads (up to 8A).

By integrating various functions into an ultra-small package, higher efficiency is achieved in a limited area without sacrificing performance.

Author: Timothy Kozono

Timothy Kozono is an Applications Engineer (AE) in the Power Products Group at ADI, where he is responsible for developing module devices and software. He received his bachelor's and master's degrees in electrical engineering from California Polytechnic State University, San Luis Obispo, in 2008 and 2010, respectively.