March 12, 2008—Littelfuse, Inc., has announced an expansion of its SP72x Series of SCR Diode Arrays for Electrostatic Discharge (ESD) and other overvoltage protection of telecomm and datacom interface circuits. The SP725 is particularly well suited for protection of microprocessor/logic inputs, data bus lines, analog device inputs, and many other voltage clamp applications, according to Littelfuse.
The thyristor-based design of the SP725 silicon diode array utilizes two bipolar SCR/diode structures to protect each of the four inputs (typically external signal or bus lines). Its operation is similar to what is known as a steering diode, but it has lower capacitance and leakage current for a given impulse rating. This means less chance of communication signal distortion, explains Littelfuse. Each SCR structure is triggered on by any current that biases the SCR into conduction against the supply rails. These internally triggered SCRs offer improved impulse protection compared to conventional diode offerings, and will serve a broader range of applications, including medical imaging, industrial equipment and test equipment.
Transients are diverted around the SP725 silicon diode array input lines to the power supply rails (or ground). Once the discharge current falls below the forward bias levels, the device stops conducting and returns the input lines to their previous condition. This design can protect up to 30V and will protect at around one volt beyond the supply rail voltage (V+ or V-). The closest competing device protects only at its breakdown voltage of 18V.
For additional information visit the Littelfuse Web site.
