Quad Bus Buffer with 3–State Control Inputs

The MC74VHCT126A is a high speed CMOS quad bus buffer fabricated with silicon gate CMOS technology. It achieves noninverting high speed operation similar to equivalent Bipolar Schottky TTL while maintaining CMOS low power dissipation. The MC74VHCT126A requires the 3–state control input (OE) to be set Low to place the output into high impedance.

The VHCT inputs are compatible with TTL levels. This device can be used as a level converter for interfacing 3.3V to 5.0V, because it has full 5V CMOS level output swings.

The VHCT126A input structures provide protection when voltages between 0V and 5.5V are applied, regardless of the supply voltage. The output structures also provide protection when VCC = 0V. These input and output structures help prevent device destruction caused by supply voltage – input/output voltage mismatch, battery backup, hot insertion, etc.

The internal circuit is composed of three stages, including a buffer output which provides high noise immunity and stable output. The inputs tolerate voltages up to 7V, allowing the interface of 5V systems to 3V systems.

• High Speed: tPD = 3.8ns (Typ) at VCC = 5V

• Low Power Dissipation: ICC = 4µA (Max) at TA = 25°C

• TTL–Compatible Inputs: VIL = 0.8V; VIH = 2.0V

• Power Down Protection Provided on Inputs

• Balanced Propagation Delays

• Designed for 2V to 5.5V Operating Range

• Low Noise: VOLP = 0.8V (Max)

• Pin and Function Compatible with Other Standard Logic Families

• Latchup Performance Exceeds 300mA

• ESD Performance: HBM > 2000V; Machine Model > 200V

• Chip Complexity: 72 FETs or 18 Equivalent Gates