Design of a Fuse-Time Testing System on STM32

Fuse, as a sacrificial device, has been widely used to provide over-current protection for many kinds of wiring systems and electrical equipments. According to the phenomenon that the fuse-time is very short under over-current condition, this paper introduces a fuse-time testing system for the low-voltage power fuse, which is based on STM32F103R8T6 MCU digital controlled parallel voltage-controlled constant-current source electronic load and can provide 0-120A controlled testing DC. Signal´s internal propagation delay in devices is reduced by using the high speed IC. And a 10-bit high precision digital-analog converter is introduced, which makes the current precision of current source reach 50mA. The two problems that the high peak pulsed current breakdowns MOSFET and the operational amplifiers of the electrical load, and the signal´s harmonic components interfere system control software have been solved respectively during system debugging. Testing experience has been successfully implemented to obtain fuse-current and fuse-time characteristics, whose precision reaches 0.01ms in its first scale.