AN020

AN020 The Power Management of PDA—The Application of SEPIC Circuit Introduction The PDA (Personal Digital Assistant) appeals to an increasing number of users because of its multifunction such as: Wireless Communication, Organizer, Mobile Phone, Handwriting Recognition, Web Access, Flash Memory, and Data/fax Modem. The users can choose their favorites among various brands according to their individual requirement. And the efficiency and the duration of the battery used in the products are critical to the users. From the designers’ point of view, the circuit for power management becomes obviously substantial. Here goes the block diagram of circuit in PDA. Referred to Fig.1, it is easily seen that there are two possible combinations for input. One way is to combine 2 Ni-MH cells and a 6V adapter. The combination causes the input voltage ranging from 1.8V to 2.6V. The other way is to put a Li-Ion battery and an adapter together. That results in a range from 2.4V to 4.3V for the input ...