The ISL9238 uses the same buck-boost operation with the four switching FETs, an inductor, and a battery connecting FET. However, it can operate in reverse boost and buck-boost mode as well to deliver power out of the USB port for charging an external electronic device. With the ISL9238, Renesas added a new “autonomous charging and end of charge feature” that allows the user to charge the battery without waking up the system. This device is pin-to-pin compatible with the ISL9237, and the EC code is also compatible if the new feature is not used.