protection
The MPSA56 part of surge protection is a type of fast-acting, axial leaded diode that is used to provide reverse polarity, transient and surge protection for circuits. It is most commonly used to protect sensitive components, such as microcontrollers, from electrostatic discharge (ESD) due to inrush currents. The device is a two-terminal, leaded diode that comes in two varieties: an axial-leaded diode with a conventional leaded package, or an SMD package. It is constructed from silicon, making it a very reliable protection device. The MPSA56 has a low forward voltage drop that allows it to protect against surges up to 20kV.