Small gas gauging devices have found their way into many consumer, industrial, and medical applications. In a previous blog post, we introduced our bq274xx series of Li-Ion gas gauges. In this video, we introduce the bq27xx series of gas gauges. The biggest difference between the bq274xx and bq275xx series is that the latter has configurable data flash to allow for more precise modeling of the rechargeable battery. Having more precise modeling of the battery provides a more accurate state-of-charge estimation. 

The bq27520-G4 and bq27541-G1 in the bq275xx series have more configurable features such as HDQ mode (one-wire communication) and SHA-1 authentication. The firmware is more advanced on bq275xx gas gauges as well, with the ability to handle swapping between two batteries, detection of internal shorts and lifetime logging parameters.

The bq27541-G1 is a pack side gas gauge which makes it very versatile for any application as it resides in a battery pack. One benefit of the solution is that it has lifetime parameters which track the maximum and minimum temperature, current, and voltage that the battery pack has gone through. System makers will often use this data to help debug a system or battery pack that has been returned from an end customer.

The bq27520-G4 is a system side gas gauge and can be placed on any system side PCB. Being on the system side eliminates the need to authenticate the battery pack. It contains the gauging algorithm and can provide interrupts to a system to indicate battery status such as low state of charge. This reduces SW overhead for the system processor allowing it to process other information and rely on the gas gauge for accurate battery monitoring.

The bq27520-G4 and bq27541-G1 also use Impedance Track technology. This allows the devices to maintain the highest accuracy across the entire life of the battery. With one device being pack side and one being system side, the bq27520-G4 and bq27541-G1 cover the necessary configurations needed to add SoC indication to any system using a rechargeable battery.

For a demonstration of how to use these two devices with their evaluation modules (EVMs), please check out these unboxing videos: