The ADP3401 is a multifunction power system chip optimized for GSM cell phone power management. It contains four LDOs, one to power each of the critical GSM sub-blocks, a step-up converter for the SIM module, and level translation circuitry to adapt logic signals for 3 V or 5 V SIM modules. Sophisticated controls are available for power up during battery charging, keypad interface and charging of an auxillary lithium coin cell battery for the real time clock. * Handles all GSM Baseband Power Management Functions * Four LDOs Optimized for Specific GSM Subsystems