Summary of Battery-pack fuel gauge with SHA-256 authentication prevents pack cloning
The MAX1720x/MAX1721x are ultra-low power fuel gauges using the ModelGauge m5 algorithm for precise state of charge estimation without host configuration. They feature SHA-256 authentication to prevent cloning, unique 64-bit IDs, and support single-cell or multi-series packs. The ICs offer temperature compensation, cycle aging forecasts, and precision measurements via I2C or 1-Wire interfaces in compact TDFN or WLP packages.
Parts used in the MAX1720x/MAX1721x Fuel Gauge Project:
- MAX17201
- MAX17211
- MAX17205
- MAX17215
- ModelGauge m5 algorithm
- SHA-256 authentication module
- Internal temperature sensor
- External thermistors (up to two)
- I2C interface
- 1-Wire interface
Description
The MAX1720x/MAX1721x are ultra-low power stand-alone fuel gauge ICs that implement the Maxim ModelGauge™ m5 algorithm without requiring host interaction for configuration. This feature makes the MAX1720x/MAX1721x excellent pack-side fuel gauges. The MAX17201/MAX17211 monitor a single cell pack. The MAX17205/MAX17215 monitor and balance a 2S or 3S pack or monitor a multiple-series cell pack.
To prevent battery pack cloning, the ICs integrate SHA-256 authentication with a 160-bit secret key. Each IC incorporates a unique 64-bit ID.
The ModelGauge™ m5 algorithm combines the short-term accuracy and linearity of a coulomb counter with the long-term stability of a voltage-based fuel gauge, along with temperature compensation to provide industry-leading fuel gauge accuracy. The IC automatically compensates for cell aging, temperature, and discharge rate, and provides accurate state of charge (SOC) in milliampere-hours (mAh) or percentage (%) over a wide range of operating conditions. As the battery approaches the critical region near empty, the ModelGauge m5 algorithm invokes a special error correction mechanism that eliminates any error. The ICs provide accurate estimation of time-to-empty and time-to-full, Cycle+™ age forecast, and three methods for reporting the age of the battery: reduction in capacity, increase in battery resistance, and cycle odometer.
The ICs provide precision measurements of current, voltage, and temperature. Temperature of the battery pack is measured using an internal temperature measurement and up to two external thermistors supported by ratiometric measurements on auxiliary inputs. A Maxim 1-Wire® (MAX17211/MAX17215) or 2-wire I2C (MAX17201/MAX17205) interface provides access to data and control registers. The ICs are available in lead-free, 3mm × 3mm, 14-pin TDFN and 1.6mm × 2.4mm 15-bump WLP packages.
Read more: Battery-pack fuel gauge with SHA-256 authentication prevents pack cloning
- How do these ICs prevent battery pack cloning?
The ICs integrate SHA-256 authentication with a 160-bit secret key and each includes a unique 64-bit ID. - What algorithms does the ModelGauge m5 combine?
It combines the short-term accuracy of a coulomb counter with the long-term stability of a voltage-based fuel gauge. - Can these ICs monitor multiple series cell packs?
Yes, the MAX17205 and MAX17215 can monitor and balance 2S or 3S packs or multiple-series cell packs. - Does the algorithm compensate for cell aging?
Yes, the IC automatically compensates for cell aging, temperature, and discharge rate. - What methods are available for reporting battery age?
The IC reports age through reduction in capacity, increase in battery resistance, and a cycle odometer. - How is battery pack temperature measured?
Temperature is measured using an internal sensor and up to two external thermistors supported by ratiometric measurements. - Which communication interfaces are supported?
The MAX17211/MAX17215 use Maxim 1-Wire, while the MAX17201/MAX17205 use a 2-wire I2C interface. - What package types are available for these ICs?
They are available in lead-free 3mm × 3mm 14-pin TDFN and 1.6mm × 2.4mm 15-bump WLP packages. - Does the system require host interaction for configuration?
No, they implement the ModelGauge m5 algorithm without requiring host interaction for configuration. - How does the system handle errors near empty battery levels?
The algorithm invokes a special error correction mechanism that eliminates any error as the battery approaches the critical region.
