MK3727

The MK3727 series of devices include the original MK3727S, MK3727A, and the new MK3727C and MK3727D. The MK3727D and MK3727C are drop-in replacements for the MK3727S and MK3727A devices. Compared to these earlier devices the MK3727D and MK3727C offer a wider operating frequency range and improved power supply noise rejection. The MK3727D is recommended for new designs.

The MK3727 series combines the functions of a VCXO (Voltage Controlled Crystal Oscillator) and PLL (Phase Locked Loop) frequency doubler onto a single chip. Used in conjunction with an external pullable quartz crystal, this monolithic integrated circuit replaces more costly hybrid (canned) VCXO devices. The MK3727 is designed primarily for data and clock recovery applications within end products such as ADSL  modems, set-top box receivers, and telecom systems.

The MK3727D is recommended for new designs. The MK3727D exhibits a moderate VCXO gain of 120ppm/V typical, when used with a high quality external pullable quartz crystal. The MK3727C offers a higher VCXO gain of 150ppm/V, similar to the earlier MK3727A. The higher intrinsic VCXO gain of the MK3727C may help compensate for the reduced pullability of a low quality crystal used in some applications. However, higher VCXO gain may also increase clock output phase noise.

The frequency of the on-chip VCXO is adjusted by an external control voltage input into pin VIN. Because VIN is a high impedance input, it can be driven directly from an PWM RC integrator circuit. Frequency output increases with VIN voltage input. The usable range of VIN is 0 to 3V.