Programmable precise frequency divider

摘要

A programmable precise frequency divider cooperating with a low frequency crystal and an oscillating circuit is disclosed. The divider includes a low frequency oscillating circuit, a preset code memory, a programmable preset code loader, an adder, and a register. The programmable preset code loader loads and latches a preset code either from the preset code memory or a preset code input line coupled to an external data source. The latched preset code and the current value of the register are commonly supplied to the adder. The adder is used to sum up the latched preset code from the programmable preset code loader and the current value from the register and thereby supply a resultant value to the register. The register accumulates the resultant value from the adder to the oscillating signal from the oscillating circuit and then supplies a output clock signal with a required divided frequency.