MELBOURNE, Fla. Harris Semiconductor has introduced a surface-mountable, low-capacitance diode-array family to protect high-speed data-communications equipment from voltage transients. The SP724 family has the ability to simultaneously protect up to four high-speed data lines (two transmit and two receive lines), thereby diverting electrostatic discharge (ESD) and other overvoltages away from sensitive data lines.
Mamoon Rashid, director of marketing for suppression products, said each SP724 uses two SCR/Diode structures of protection per four device inputs. The diode structures are triggered at the moment any transient voltage exceeds 0.7 V above V+ or -0.7 V below V- supply rails and provides much lower clamping than traditional Zener-based transient-voltage-suppression diodes.
The SP724 is designed for applications ranging from 3.3 V to 20 V and provides fast switching, with typical rise times of 2 ns. The diode arrays meet IEC 1000-4-2 specifications by protecting circuits from up to 15,000 V of air discharge and 8,000 V of direct-discharge ESD.
Unlike Zener arrays, Harris' SP724 family is not affected by power-supply variations. The SP724 works with any supply voltage within its range. Low-input leakage (1nA at 25 degrees C typical) and low-input capacitance (3pF typical) are said to suit the SP724 for protecting LAN transceivers, microprocessor and logic input devices, data buses and analog input devices.
The diode arrays provide voltage clamping over a temperature range of -40 degrees C to 150 degrees C. They can be surface-mounted in PCMCIA cards and on the back side of PC boards. They are available in six-lead SOT23 packages and are priced at 58 cents per unit for quantities greater than 12,000.
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EETInfo No. 634