FSTUD162450

FSTUD162450 Configurable 4-Bit to 20-Bit Bus Switch with −2V Undershoot Protection and Selectable Level Shifting and 25Ω Series Resistors in Outputs April 2001 Revised August 2001 FSTUD162450 Configurable 4-Bit to 20-Bit Bus Switch with −2V Undershoot Protection and Selectable Level Shifting and 25Ω Series Resistors in Outputs General Description The Fairchild Universal Bus Switch FSTUD162450 provides 4-bit, 5-bit, 8-bit, 10-bit, 16-bit, 20-bit of high-speed CMOS TTL-compatible bus switching. The low On Resistance of the switch allows inputs to be connected to outputs without adding propagation delay or generating additional ground bounce noise. The FSTUD162450 is designed to allow “customer” configuration control of the enable connections. The device can be organized as either a five 4-bit, four 5-bit, two 10-bit or one 20-bit bus switch. Also available are 8-bit and 16-bit enabled configurations (see Functional Description). The device's bit configuration is controlled through select pin logic. (see Truth Table). When OEx is LOW, Port Ax is connected to Port Bx. When OEx is HIGH, the switch is OPEN. The A and B Ports are protected against undershoot to support an extended range to 2.0V below ground. Fairchild's integrated Undershoot Hardened Circuit (UHC) senses undershoot at the I/O and responds by preventing voltage differentials from developing and turning the switch on. Another innovative device feature is the addition of a level shifting select pin, “S2”. When S2 is...