January 21, 2020
| By: Sagar Khare
Executive Business Manager, Mobile Solutions Business Unit, Maxim Integrated
With the increasing popularity of portable devices, lithium-ion (Li-ion) batteries have become ubiquitous. These batteries, however, have stringent safety requirements which typically require battery packs with integrated protectors.
The characteristics of Li-ion batteries also often warrant battery fuel gauges to accurately report state-of-charge (SOC) under various operating and environmental conditions. Depending on the type of applications, the system may be designed with a host-side fuel gauge (Figure 1) or a pack-side fuel gauge (Figure 2). A host-side fuel gauge resides on the host system and is connected to the application processor, while a pack-side fuel gauge resides on the battery pack and is connected to the Li-ion cell.
Figure 1. Host-side fuel-gauge implementation.Host-side fuel gauges are useful when the battery pack is replaceable and lower SOC accuracy is acceptable for the application. Increasingly, however, devices are being designed with captive batteries with no option to replace them. In these cases, a pack-side fuel gauge may be suitable for the technical reasons as outlined below, or for logistical reasons. For example, there may be multiple cells being used by multiple battery pack makers for supply assurance, as each battery can carry its cell parameters inside the pack-side fuel gauge.
Figure 2. Pack-side fuel-gauge implementation.
In the pack-side approach, the proximity of the cells to the fuel gauge results in a number of unique advantages:
Maxim's MAX17301/11 fuel gauge with protector and SHA-256 authentication (Figure 3) is an example of a solution that simplifies pack-side fuel-gauge implementation. The IC integrates a 2-level protector and SHA-256 authentication to the industry's most accurate battery fuel gauge. MAX17301/11 offers the following features that are useful for pack-side fuel gauging:
Figure 3. MAX17301/11 functional diagram
So, for your next Li-ion battery-based design, consider a pack-side fuel-gauge implementation. The battery—and the device user—might just thank you for this!