New Buck/Boost Regulator Focuses on Managing Supercapacitor Backup Power Systems

June 01, 2021 by Kate Smith

Today, Maxim Integrated released a new PMIC with supercapacitor backup power supplies in mind.

Supercapacitors, capacitor banks, and batteries are common backup power solutions that require both reliability and power efficiency in charging and discharging power quickly. Today, Maxim Integrated released a new buck/boost regulator PMIC (power management integrated circuit) for managing such backup power systems, the MAX38889.


The simplified block diagram of the MAX38889. Image from Maxim Integrated.


The buck/boost regulator design entails entering buck mode to charge a backup power supply and then entering boost mode to control boosting the needed voltage to sustain the power system until primary power sources are restored.


The Most Noteworthy Specs (According to Maxim)

Maxim highlighted a few specs and accompanying claims with the announcement of this device:

  • 94% power efficiency, 9% higher than their nearest cited competitor
  • 2.5% voltage regulation
  • A 64% reduction in package size compared to their nearest cited competitor

That last point bears repeating as it’s the primary feature touted by Maxim for the MAX38889 overall.


Why Size Matters

Maxim Integrated claims that the MAX38889 has a major leg up over its nearest competitors in terms of device footprint: a 64% reduction in package size, measuring only 3.10 mm x 3.10 mm x 0.80 mm.

Maxim points out that this is a key consideration for the applications they’ve targeted for this component, namely healthcare, automotive, industrial, and especially asset tracking. Across the board for these applications, space is at a high premium as the pressure is on for smaller, more power-efficient devices from biometric monitors to dash cams.


The MAX38889 package. Image from Mouser.


As a note, it’s perhaps not immediately obvious why industrial applications require smaller footprints, given that traditional industrial facilities aren’t precisely short on space.

In a recent interview with Qualcomm (held jointly with our sister site, Control Automation), we spoke with Vieri Vanghi, Vice President of Product Management, about the importance of small form factors in moving towards wireless smart facilities. While Vanghi was talking specifically about this concept in the context of migration to 5G, the lesson is applicable across the board for industrial applications: revolutionizing the factory floor starts at the chip level.

The name of the game appears to be integration, as the MAX38889 press release points out: "Smaller size also makes it easier to integrate into new and existing designs with tight space constraints."

This parallels Vanghi's point that more configurable, updated factory floors start with packing more features into form factors that are easy to drop into existing designs.

All of this being said, the MAX38889 actually ultimately has the same form factor dimensions as its sister component, the MAX38888. They differ in the package type (TDFN-CU for the MAX38888 and TQFN-CU for the MAX38889) and pin number (14 pins for the MAX38888 and 16 pins for the MAX38889). This does not minimize the importance of compact form factors, but may be of consequence when deciding which component to select for a design.


The Continua Family

The MAX38889 is the latest out of Maxim Integrated’s Continua family of buck/boost regulators “for backup power applications.” Other analog PMICs in the Continua family include the MAX38888, which honed in on wearables, home security control panels/gateways, and building automation applications.

By comparison, the MAX38889 focuses on healthcare, automotive, industrial, and asset tracking applications.


A look at some of the intended end devices for the MAX38889. Cropped image used courtesy of Maxim Integrated.


As a minor note, the MAX38888 actually reported 95% peak efficiency, beating out this newest Continua member by 1%. The tradeoff, of course, appears to be range. Where the MAX38888 has a system voltage range of 2.5 V–5.0 V and a peak inductor current of 2.5 A, the new MAX38889 has a system voltage range of 2.5 V–5.5 V and a peak inductor current of 3 A.



An evaluation kit is available, the MAX38889EVKIT, for those who wish to see if this PMIC is a suitable fit for their backup power supply project.


The MAX38889EVKIT. Image from Maxim Integrated.


Have you designed backup power systems? What challenges have you come across and what solutions did you call on to address them? Share your experiences in the comments below.