What this charge pump does on your board
The Maxim MAX889TESA+T is an adjustable step-down charge pump regulator that generates a negative output voltage from a positive input rail. It delivers up to 200 mA and switches at 2 MHz.
The 2 MHz switching frequency pushes ripple into a band where a small LC post-filter (if needed) is effective, but it also means layout matters: keep the flying capacitor traces short and the ground plane continuous under the IC. No synchronous rectifier inside, so expect a Schottky diode on the output for the return path.