TISP61089BDR-S

The TISP61089B is a dual forward-conducting buffered p-gate thyristor (SCR) overvoltage protector. It is designed to protect monolithic SLICs (Subscriber Line Interface Circuits) against overvoltages on the telephone line caused by lightning, a.c. power contact and induction. The TISP61089B limits voltages that exceed the SLIC supply rail voltage. The TISP61089B parameters are specified to allow equipment compliance with Bellcore GR-1089-CORE, Issue 2 and ITU-T recommendations K.20, K.21 and K.45. The SLIC line driver section is typically powered from 0 V (ground) and a negative voltage in the region of -20 V to -150 V. The protector gate is connected to this negative supply. This references the protection (clipping) voltage to the negative supply voltage. The protection voltage will then track the negative supply voltage and the overvoltage stress on the SLIC is minimized. Positive overvoltages are clipped to ground by diode forward conduction. Negative overvoltages are initially clipped close to the SLIC negative supply rail value. If sufficient current is available from the overvoltage, then the protector SCR will switch into a low voltage on-state condition.As the overvoltage subsides, the high holding current of TISP61089B SCR helps prevent d.c. latchup. The TISP61089B is intended to be used with a series combination of a 40 ? or higher resistance and a suitable overcurrent protector. Power fault compliance requires the series overcurrent element to open-circuit or become high impedance (see Applications Information). For equipment compliant to ITU-T recommendations K.20 or K.21 or K.45 only, the series resistor value is set by the coordination requirements.The TISP61089B is available in a 8-pin plastic small-outline surface mount package.

• Dual Voltage-Programmable Protectors
• Supports Battery Voltages Down to -155 V
• Low 5 mA max. Gate Triggering Current
• High 150 mA min. Holding Current