The main difference between the MAX17048 and MAX17049 fuel gauges is the number of lithium-ion (Li+) battery cells they are designed for. The MAX17048 operates with a single lithium cell, while the MAX17049 operates with two lithium cells in series.

The advantages of using the MAX17048 are its simplicity and lower cost for single lithium cell applications. It is suitable for devices that require a smaller battery capacity, such as wearables, IoT devices, and small portable electronics.

On the other hand, the MAX17049 is ideal for applications that require a higher voltage or more energy capacity, as it can monitor two lithium cells in series. This makes it suitable for devices that demand more energy, such as laptops, power tools, and other high-capacity portable devices.

Both fuel gauge ICs provide accurate battery state-of-charge (SOC) estimation and other useful battery monitoring features. The choice between the MAX17048 and MAX17049 depends on your specific application requirements. If your project is powered by a single lithium cell, go for the MAX17048. If it requires two lithium cells in series, then choose the MAX17049.

Should I use the MAX17043 or the MAX17048 for my application considering I'm designing a PCB for a wearable?

Both the MAX17043 and MAX17048 are suitable for wearable applications, as they are designed for monitoring single lithium-ion (Li+) battery cells. They both offer low power consumption and small form factors, making them ideal for wearable devices, IoT devices, and portable electronics.

The primary difference between the MAX17043 and MAX17048 lies in their communication interfaces. The MAX17043 uses an I2C interface, while the MAX17048 uses an SPI interface. Therefore, the choice between these two ICs depends on your design preference, available microcontroller peripherals, and overall system requirements.

If your microcontroller or system is more suited for or has available I2C communication, then the MAX17043 would be a better fit. On the other hand, if your system design favors SPI communication or has available SPI peripherals, then you should opt for the MAX17048.