Posted on 29 June 2019

Benefits of Digital Power Modules for Advanced Industrial and Communications Applications

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Encapsulated modules in some cases can have four times higher power density

After a long period of development and design, the DC/DC power supply module is coming into its own as an effective and efficient solution for a wide range of communications and industrial applications can finally take advantage of the benefits of non-isolated DC/DC power supply modules, There are several immediate advantages to notice about the DC/DC power module.

By Josh Broline, Intersil


Most notable, they can reduce its size, delivering a complete, integration solution that includes passives, inductors, controllers, and MOSFETS. Also, they can add significantly to the portability of a design design’s portability, while reducing its size. DC/DC non-isolated power modules offer a complete range of current and voltages in rugged, standard packaging at a reasonable cost. They are an excellent design option now for the next generation of communications systems and industrial products.

The DC-DC power module combines most or all of the components necessary to deliver a plug-and-play solution that can replace up to 40 different components. This integration simplifies and speeds designs. It also significantly reduces the total power management footprint. The modules can be placed on the printed circuit board close to the circuits they power, which aids in voltage regulation. Placement becomes even more critical as subsystems operate at higher currents, lower voltages and higher clock frequencies.

The most common of the non-isolated DC-DC power modules are single in-line packages (SIP), open frame solutions that definitely can simplify design. But they typically are useful for lower frequency designs, for example, in the 300kHz range and below. Also, their power density often is not optimal, particularly in comparison with DC-DC modules.

These kinds of modules can help shorten total end product time-tomarket and reduce the need for manufacturers to develop power design expertise. But they require a comprehensive evaluation because there are different options. Engineers must compare their specific application requirements with a module’s electrical and thermal performance, physical dimensions, and reliability specifications available from traditional and emerging, higher power density options with optimal thermal resistivity.

Fully Encapsulated Modules

The newest form of module is the fully encapsulated DC/DC POL digital power module supply, which delivers the ultimate combination of advantages provided by a digital power solution via the PMBus and encapsulated module packaging. Enabled by the internal digital controller, the PMBus can be used to configure a wide variety of parameters to adapt to specific application needs. Various parameters can be monitored and stored in on board nonvolatile memory, and as with most advanced modules now, almost all discrete components are integrated. Advantages can include reduced time-to-market, minimized BOM on the PCB, and increased long-term reliability. Fully encapsulated packaging provides large thermal pads on the bottom of the package for enhanced thermal capability and exposed leads around the edge of the package for ideal solder joint inspectability. With the ability to run off 3.3V, 5V, 12V bias rails and output a voltage from 0.54 to 4V, with a single resistor setting, and up to 12A of output current, a fully encapsulated digital module is versatile enough to meet a fairly wide range of application requirements.

One of the major advantages of an encapsulated digital power module is superior power density enabled by improved package thermal performance. Power density and thermal resistivity of the package go hand-in-hand, especially when considering a high power solution, defined as greater than 25W. There has been a race to improve density/integration for decades in the semiconductor industry. The bottom line reason is systems are growing in functionality (which requires more components and are being reduced in size to stay competitive. So component/solution size is a key part of this trend, which means the customer can fit more content or a higher/larger power processor, for example, on a PCB. One example is the server application or automated test equipment (ATE).

The lower the thermal resistivity, the higher the possible power density — some encapsulated module solutions struggle to meet higher power levels due to their package thermal resistivity. Also, the more thermally efficient the solution is, the less a user needs to be concerned with or design around the solution constraints, such as ensuring there is a specific amount of air flow, or adding a heat sink.

Optimal thermal performance is enabled by the enhanced encapsulated QFN package with the large pads on the bottom of the package and the thermally enhanced package overmold material that acts as a heat spreader. Very low package thermal resistivity can be demonstrated by a package theta junction-to-ambient of 11.5C/W and bottom of the package theta junction-to-case of 2.2C/W. As a result, a higher power solution can be designed in a smaller form factor. Because the theta JC on the backside of the package is so low, the majority of the heat is dissipated through the bottom of the package. In contrast to an open framed module, no air flow is required to run at full load over the industrial ambient temperature range in most operating conditions. The thermal capability of a module package has a major influence in achieving a higher power density than more traditional open-framed modules or discrete power solutions, and makes the encapsulated module a solid choice to replace either.

Encapsulated module solutions tend to have higher reliability and manufacturability. For example, since all the components are fully encapsulated, there is better electrical isolation from the outside world, less solder joints that can go bad over time, lower chance of stresses in a given application causing package cracks, and improved manufacturability since the encapsulated package is more conducive to traditional pick-and-place equipment versus a non-planar open framed solutions.

In addition to the encapsulated package, another advantage of this kind of module comes in the ability to configure and monitor digital power management using the PMBus and I2C interface. The best way to achieve these benefits is through a simple graphical user interface that lets designers adjust various operating parameters such as soft start ramp time, output voltage margining, voltage tracking and power-good threshold. No external circuitry is required using this method, and it is designed to be flexible enough to meet current and future design requirements.

Various parameters can be monitored during the system development stage and after the system is deployed out to the field. For example, the output conditions, voltage and current, can be monitored and stored in the internal nonvolatile memory with a date stamp on a regular bases and read back externally as needed. This enhances system design by speeding up debugging time and increases long-term system reliability by insuring normal operation at all times or enhancing failure analysis if a system is returned. Once a configuration is finalized for a specific application, the config file is produced by using the configuration program.

Significant Advances in Power Density

As an example of the newest DC/DC encapsulated power module, the ZL9101MIRZ from Intersil offers a very unique combination of next generation package technology and easy to use digital power management that will simplify potential sophisticated POL power supply design due to minimal external components, improve reliability over traditional open framed modules or discrete solutions, and improve design cycle time or time to market. It applies a system called PowerNavigator with the PMBus and a GUI to simplify and optimize configuration and monitoring.

Encapsulated modules in some cases can have four times higher power density. For example, comparing the Intersil ZL9101MIRZ to an equivalent open framed module on the market, the ZL9101M has a power density of 38W/cm3 versus 8.6W/cm3, over three times higher than this equivalent open framed module at the equivalent output power level of 30W. There is also a significant difference in the x and y footprint of the two solutions, 2.2cm2 versus 3cm2, a 30 percent difference, which is critical when board space is at a minimum.

Benefits of the Heat Spreading Effect in Encapsulated Module

Encapsulated digital power module technology offers an advantageous combination of next- generation package technology and easily implemented digital power management that will simplify POL power supply design with minimal external components, improved reliability over traditional open framed modules or discrete solutions, and enhanced design cycle time. DC/DC non-isolated power modules offer a complete range of current and voltages in rugged, standard packaging at a reasonable cost. They are an excellent design option now for the next generation of communications systems and industrial products.



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