Toshiba AMOBEADS® and SPIKE KILLERs™ - Toshiba America Electronics Components - #1

Text version of the page

Toshiba’s amorphous magnetic Noise Suppressors are essentially small saturable cores. The square-shaped magnetic hysteresis of these devices is key to their noise suppression ability. They are most effective at suppressing the noise associated with the reverse recovery of diodes. Toshiba offers two types of devices, which have been specifically designed for noise suppression: AMOBEADS®and SPIKE KILLER™. AMOBEADS are smaller than SPIKE KILLERs and have been designed for a single turn. They are simply slipped over the lead of a diode and require no additional circuit board space (also available in a surface mount configuration). SPIKE KILLERs are used when AMOBEADS are insufficient to handle the noise in a particular circuit. They are typically wire wrapped as an inductor. For even larger noise problems, Toshiba’s saturable cores can be used as SPIKE KILLERs.How Do They Work? Amorphous Magnetic Noise Suppressors Figure 2: Magnetic Behavior of a Saturable CoreI H II Figure 1: Current Through a Switching Diode I IIReverseRecovery To better understand the mechanism by which these devices suppress noise, consider a switching diode, with current as shown in Figure 1, in series with a saturable reactor (i.e. wire wrapped saturable core). Figure 2shows the magnetic hysteresis curve the reactor would follow. The Magnetic Field, H, is proportional to the current flowing in the reactor while the slope of the hysteresis curve is proportional to the inductance of the reactor at the corresponding value of current.When the diode is conducting (Region I in Figure 1), current flows in one direction through the reactor. This situation corresponds to the nearly horizontal region in Figure 2. The slope of the curve in this region is small, therefore a very low inductance is put in series with the diode while it is conducting. www.suppressnoise.toshiba.com t rr