CD74HC297E (TEXAS INSTRUMENTS)

The CD74HC297E is a high-speed silicon gate CMOS Device that is pin-compatible with low power Schottky TTL (LSTTL). This device is designed to provide a simple, cost-effective solution to high-accuracy, digital, phase-locked-loop applications. They contain all the necessary circuits, with the exception of the divide-by-N counter, to build first-order phase-locked-loops. Both EXCLUSIVE-OR (XORPD) and edge-controlled phase detectors (ECPD) are provided for maximum flexibility. The input signals for the EXCLUSIVE-OR phase detector must have a 50% duty factor to obtain the maximum lock-range. The length of the up/down K-counter is digitally programmable according to the K-counter function table.