Thyristor Semiconductor Products Page 21 Thyristor

2014 Littelfuse, Inc. Specifications are subject to change without notice. Revised: 12/14/14 Teccor brand Thyristors AN1001 Electrical Characteristic Curves of Thyristors Reverse Breakdown Voltage Forward Breakover Voltage Specified Minimum Off - State Blocking Voltage (V DRM ) +I -I +V -V Minimum Holding Current (I H ) Voltage Drop (V T ) at Specified Current (i T ) Latching Current (I L ) Off - State Leakage Current - (I DRM ) at Specified V DRM Specified Minimum Reverse Blocking Voltage (V RRM ) Reverse Leakage Current - (I RRM ) at Specified V RRM +I -I 10 mA +V -V Breakover Current I BO Breakover Voltage V BO V -V +I V DRM +V V S I S I H R S I DRM I BO V BO V T I T (I S - I BO ) (V BO - V S ) R S = -I Breakover Voltage Specified Minimum Off-state Blocking Voltage (V DRM ) +I -I +V -V Minimum Holding Current (I H ) Voltage Drop (v T ) at Specified Current (i T ) Latching Current (I L ) Off-state Leakage Current - (I DRM ) at Specified V DRM Methods of Switching on Thyristors Three general methods are available for switching Thyristors to on-state condition: Application Of Gate Signal Gate signal must exceed I GT and V GT Thyristor used. For an SCR (unilateral device), this signal must be positive with respect to the cathode polarity. A Triac (bilateral device) can be turned on with gate signal of either polarity; however, different polarities have different requirements of I GT and V GT which must be satisfied. Since DIACs and SIDACs do not have a gate, this method of turn- on is not applicable. In fact, the single major application of DIACs is to switch on Triacs. Static dv/dt Turn-on Figure AN1001.16 Internal Capacitors Linked in Gated Thyristors Static dv/dt turn-on comes from a fast-rising voltage applied across the anode and cathode terminals of an SCR or the main terminals of a Triac. Due to the nature of Thyristor construction, a small junction capacitor is formed across each PN junction. Figure AN1001.16 shows how typical internal capacitors are linked in gated Thyristors. Fundamental Characteristics of Thyristors (continued)

Previous Page
Next Page