The power of DIY: Simplifying your design process with user-programmable PMICs

By Andrew Goodson, product marketing engineer, Texas Instruments Inc.

Imagine that you found the perfect processor for your application. This processor has the performance and the peripherals you need, including serial peripheral interface, universal asynchronous receiver transmitter, USB, and I² C. It also has all of the correct communication protocols, like Ethernet and EtherCAT. This processor matches your project requirements perfectly.

Your next logical focus shifts to the power solution for the processor. You sort through tens of thousands of DC/DC regulators, low-dropout regulators, boosts, sequencers, and supervisors. With your small form factor, how will you squeeze all of these components onto your board? Will you have time to complete the design before the project deadline? Will the sequencing work for the processor? How will you manage the software between the processor and the power solution? The challenges begin to mount.

To address many of these challenges, design engineers often choose to work with multi-channel power-management integrated circuits (PMICs). PMICs are tightly coupled with processors because they integrate many discrete components into one power solution and provide the necessary voltages, power-up/power-down sequencing, and system diagnostics that the processor requires. These settings are stored in a nonvolatile memory so that when the PMIC is powered on, it can operate according to the processor specifications. By choosing a PMIC, you can reduce the overall board size, simplify your design effort, and decrease time to market.

Getting ahead of design changes

So let’s assume that you select a companion PMIC for your processor, but later in the design, the project requirements change. Now you must use a higher-power processor. The PMIC that you previously selected can technically provide the power needed for this new processor, but the default output voltages and startup sequence are a mismatch. Your old PMIC was programmed by the PMIC manufacturer with custom settings for your old processor. Assuming that you are still committed to designing with a PMIC because of its system benefits, you now face some major challenges in adapting the PMIC from the first processor you selected to the second processor, including a lengthy standard sample timeline and an even lengthier standard schedule for product release.

Here is an example of a typical workflow for factory programming a PMIC with customized settings:

1.     The designer has interest in a PMIC, but it requires customization.

2.     The designer engages with the PMIC supplier to determine PMIC default settings such as the output voltages, power-up and power-down sequencing, or other special device features; the timeline is approximately one week.

3.     The PMIC supplier programs samples of the factory-programmable PMIC; the timeline is approximately two to four weeks.

4.     The PMIC supplier ships the programmed samples to the designer; the timeline is approximately three days.

5.     The designer evaluates the newly factory-programmed PMIC settings based on whether the settings fit their system requirements; the timeline is approximately one to two weeks.

6.     If the designer has different system requirements or the processor requirements change, repeat Steps 2 through 5 as necessary.

The lead time for each step varies by supplier, but if you consider discussion response time, sample programming time, material availability of the PMIC, and even the shipping time, the sample process can take anywhere from five to eight weeks or more for a factory-programmed PMIC with customized settings.

Choosing the DIY route

What if you were able to reprogram the PMIC yourself during the prototyping phase so that it works for the new processor? With a user-programmable PMIC, the device is released to market with the default settings typically blank, eliminating the factory-programmable development process. A user-programmable PMIC simplifies the development process because it’s user-programmable; thus, it matches the power requirements of your new processor.

User-programmable PMICs offer similar benefits to factory-programmed PMICs in terms of space savings, cost savings, and simplicity in the final design. They also solve the challenges associated with factory-programmed PMICs and drastically reduce the sample and product release timelines.

Contrary to the sample process for a factory-programmable PMIC, sampling a user-programmable PMIC is much faster and much simpler. You can quickly program a user-programmable PMIC by using a sample toolkit like a socketed programming board and a sample of the PMIC.

Here is an example of a typical workflow for programming a PMIC if you customized the settings yourself:

1.     The designer has interest in a PMIC, but it requires customization.

2.     The designer orders a socketed programming board and samples of the user-programmable PMIC; the timeline is approximately three days.

3.     Referencing the appropriate training collateral, the designer programs samples of the user-programmable PMIC in as fast as a few minutes. The settings that can be programmed are output voltages, power-up and power-down sequencing, or other special device features.

4.     The designer evaluates the newly programmed samples.

Taking advantage of reusability

An additional benefit of user-programmable PMICs is that they enable PMIC reusability across platforms.

Let’s consider a scenario in which you’ve completed a PMIC power design for a processor. The next project requires you to design a new system, and you select a different processor. If you were to design with a customized PMIC for both projects, you might end up designing with either two completely different PMICs or two customized variants of the same PMIC.

Designing with two different PMICs will introduce a steep learning curve, wherein you must learn the features of a new device. You cannot reuse the knowledge gained during the design process for the previous PMIC. Even if you design with two customized variants of the same PMIC, you cannot benefit from the improved prototype development.

Often considered a custom option, or exclusively for high-volume opportunities, today’s PMICs are becoming more widely available. You can implement pre-configured PMICs for a given application immediately without much design effort, but you may face some challenges when requirements change mid-design.

A user-programmable PMIC allows you to reuse the same PMIC for multiple projects, provided that the PMIC has the ability to satisfy the power requirements of each project, all while speeding up your prototyping and reducing time to market.

Andrew Goodson is a product marketing engineer for TI’s multiphase and controller solutions. Andrew earned his B.S. and M.S. in electrical engineering from Southern Methodist University.