SMBus Level 2 Battery Charger with Remote Sense
The MAX8731 is an SMBus™ programmable multichem- istry battery charger. The MAX8731 uses a minimal command set to easily program the charge voltage, charge current, and adapter current limit. The MAX8731 charges one to four Li+ series cells and delivers up to 8A charge current. The MAX8731 drives n-channel MOSFETs for improved efficiency and reduced cost. Low-offset current-sense amplifiers provide high accuracy with 10m Ω sense resistors. The MAX8731 current-sense amplifiers provide high accuracy (3% at 3.5A) and also provide fast cycle-by-cycle current-mode control to protect against battery short circuit and system load transients. The charger employs dual remote-sense, which reduces charge time by measuring the feedback voltage directly at the battery, improving accuracy of initial transition into constant-voltage mode. The MAX8731 provides 0.5% battery voltage accuracy directly at the battery terminal. The MAX8731 provides a digital output that indicates the presence of the AC adapter, as well as an analog output that indicates the adapter current within 4% accuracy.