Littelfuse Silicon Diode Arrays

DES PLAINES, IL,– Littelfuse, Inc. (NASDAQ/NGS:LFUS) 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. It far surpasses the closest competition in the following ratings:

* Operating voltage range — 2 to 30V
* Surge current — 14A with an 8×20µs waveform
* Response time — 2ns rise time
* Input capacitance — 5pF maximum
* Leakage current — 5nA typical, 20nA maximum

Product Details. 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. 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: MRI, X-ray, CT scan, Ultrasound
* Medical analysis: Chemical analyzer, blood/tissue analyzer
* Industrial equipment: Process controller, CNC machine
* Test equipment: Oscilloscope, frequency analyzer
* Vehicular: Engine control module, body control module

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.

Purchasing, Assembly and Compliance Information. A significant result of the SP725’s broad voltage range is the ability of manufacturers to use it in different products employing different rail voltages. By comparison, Zener diode protectors can only be used on rails up to their standoff voltage, so different protectors are needed for different rail voltages (for example, 3.3V, 5V, 12V, etc.). Thus, the SP725 silicon diode array can help reduce manufacturers’ component inventories and simplify their purchasing supply lines.

The SP725 Series silicon diode array circuit protection device is available in an 8-lead, narrow body SOIC package, which can be supplied in tape and reel assemblies. It is RoHS compliant and fully lead-free, in contrast to competitive units that still use lead solder for attachment of the IC to heat dissipaters. The SP725 also meets the test requirements of IEC 61000-4-2 for 8kV direct discharge and 15kV air discharge. Unlike the competition, it also meets the requirements of MIL-STD-3015.7 for 25kV testing.

www.littelfuse.com

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