Battery-pack fuel gauge with SHA-256 authentication prevents pack cloning

June 01, 2016 // By Graham Prophet
Implementing pack-side battery gauges in portable devices is easier and more secure, Maxim asserts, with its ModelGauge m5 portfolio of MAX17201/MAX17205 and MAX17211/MAX17215.

Fuel gauging can be difficult because battery voltage varies with temperature and load, while coulomb-counting requires sophisticated compensation to eliminate offset accumulation errors. Maxim’s ModelGauge m5 fuel gauges include a sophisticated algorithm that converts raw measurements such as battery voltage, current, and temperature into accurate state-of-charge (SOC%), absolute capacity (mAhr), time-to-empty, and time-to-full (while charging), all of which improve the user experience of the host device while enabling maximum run-time. To ease the design process, the ModelGauge m5 EZ configuration eliminates the time and resource-consuming characterization process for a large number of battery types. ModelGauge m5 fuel gauges are also the first to integrate SHA-256 for secure authentication to prevent battery clones.

 

Battery packs generally need to be replaced every few years—when batteries age, their characteristics change over time and no longer provide adequate run-time. The ModelGauge m5 robust algorithm detects the smallest changes in the capacity of the battery to more accurately predict how long the battery will last before the capacity degrades rapidly. With the Cycle+ age forecast information from ModelGauge m5 fuel gauges, system designers are able to adjust charger parameters to extend the battery life, or to plan a timely replacement of the battery. ModelGauge m5 devices are suitable for any rechargeable battery operated device.

 

Features include;

 

- Fast time to market: No battery characterization or calibration required with EZ configuration

- Highest accuracy: No need to reset to track battery usage correctly; learns capacity without battery going to full, empty, or relaxed state

- Unique Cycle+ age forecasting: Predicts aging and how long the battery will last before replacement is required

- Strongest security: SHA-256 authentication combined with a 160 bit secret key , makes it harder to clone battery packs

- Low quiescent current: 9 µA low-power operation (MAX17201/MAX17211); 12 µA low-power operation (MAX17205/MAX17215)

 

In a 14-pin, TDFN package (3 x 3 mm) and specified over the -40to +85C temperature