The rapid development of electronic technology not only makes that a wide range of portable electronic products are moving in the direction of light weight and small-scale development, but also makes products more electrification of the power supply system based on the battery. Therefore, there raises the need for a wide range of chargers to work. In order to more quickly use a variety of electronic products, the requirements of the charger is getting higher and higher.
The issue consisted of AT89S52 single-chip computer as a core control circuit unit, battery capacity sampling, AD0809 analog-to-digital conversion to determine the value of pre-charge, automatic switching current - voltage charge access, and LM317 designed as current source and voltage source.
Hardware design took Protel99 SE tools, software tools took C language programming Keil. Simulation debugging system showed that the design achieved expected object.
Keywords：Sampling voltage；Constant current charge； Constant voltage charge；Single-chip microcomputer system
