Other Parts Discussed in Thread: BQ27220,
Tool/software:
Dear TI team.
Our device originally used the BQ27220 fuel gauge, and we're now reevaluating our fuel gauge choice during a design revision phase. While reviewing alternatives, we came across Impedance Track-based algorithms and learned from TI's documentation that it offers higher accuracy than the CEDV algorithm, particularly over a wider range of load and battery aging conditions.
Upon closer inspection, we noticed that BQ27220 and BQ27427 appear to have very similar electrical characteristics, including quiescent current, and even the reference schematic and pinout look almost identical. This led us to consider migrating to BQ27427 for improved SoC accuracy without changing our hardware much.
Here's a brief of our application:
- Battery: 50 mAh Li-Polymer
- Sleep current: < 50 µA
- Active current: ~1–2 mA
- Usage pattern: The device is usually fully recharged before each use and operated continuously until nearly empty.
We would appreciate your support on the following questions:
- Would migrating from BQ27220 to BQ27427 provide noticeably better SoC accuracy in our usage case?
- Are these two parts pin-to-pin compatible (or nearly so) for straightforward replacement?
- Can the Impedance Track algorithm operate reliably with our charge/discharge pattern?
- Do you recommend any other fuel gauge ICs that may be even more suitable for our low-capacity, low-power IoT device?
Our system uses I2C communication, and we prefer minimal host MCU involvement, along with very low quiescent current, especially during sleep.
We would greatly appreciate your guidance.
