MC74VHCT393A

MC74VHCT393A Advance Information Dual 4−Bit Binary Ripple Counter The MC74VHCT393A is an advanced high speed CMOS dual 4−bit binary ripple counter fabricated with silicon gate CMOS technology. It achieves high speed operation similar to equivalent Bipolar Schottky TTL while maintaining CMOS low power dissipation. This device consists of two independent 4−bit binary ripple counters with parallel outputs from each counter stage. A ÷256 counter can be obtained by cascading the two binary counters. Internal flip−flops are triggered by high−to−low transitions of the clock input. Reset for the counters is asynchronous and active−high. State changes of the Q outputs do not occur simultaneously because of internal ripple delays. Therefore, decoded output signals are subject to decoding spikes and should not be used as clocks or as strobes except when gated with the Clock of the VHC393. The VHCT inputs are compatible with TTL levels. This device can be used as a level converter for interfacing 3.3 V to 5.0 V because it has full 5 V CMOS level output swings. The VHCT393A input structures provide protection when voltages between 0 V and 5.5 V are applied, regardless of the supply voltage. The output structures also provide protection when VCC = 0 V. 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...