Description ¡El FAN49103 is a high efficiency buck−boost switching mode regulator which accepts input voltages either above or below the regulated output voltage. Using full− bridge architecture with synchronous rectification, the FAN49103 is capable of delivering up to 2.5 A while regulating the output at 3.4 V. ¡El FAN49103 exhibits seamless transition between step−up and step−down modes reducing output disturbances. ¡El output voltage and operation mode of the regulator can be programmed through an I2C interface. At moderate and light loads, Pulse Frequency Modulation (PFM) is used to operate the device in power−save mode to maintain high efficiency. In PFM mode, the part still exhibits excellent transient response during load steps. At moderate to heavier loads or Forced PWM mode, the regulator switches to PWM fixed−frequency control. While in PWM mode, the regulator operates at a nominal fixed frequency of 1.8 MHz, which allows for reduced external component values. ¡El FAN49103 is available in a 20−bump 1.615 mm x 2.15 mm with 0.4 mm pitch WLCSP.