CDCE(L)937 Programmable VCXO Clock Synthesizers Texas Instruments CDCE(L)937 Programmable VCXO Clock Synthesizers are modular PLL-based programmable clock synthesizers, multipliers, and dividers that generate up to 7 output clocks from a single input frequency. Each output can be programmed in-system for any clock frequency up to 230MHz, using up to three independent configurable PLLs. The CDCx937 has separate output supply pins, VDDOUT, which is 1.8V for CDCEL937 and 2.5V to 3.3V for CDCE937. The input accepts an external crystal or LVCMOS clock signal. If an external crystal is used, an on-chip load capacitor is adequate for most applications. The value of the load capacitor is programmable from 0 to 20pF. An on-chip VCXO is selectable, allowing synchronization of the output frequency to an external control signal.