PLL core with integrated VCO and lock detection
The CD74HC7046AM is a single-circuit phase-locked loop (PLL) that integrates a voltage-controlled oscillator (VCO) and a lock detector, per the 74HC logic family. It accepts CMOS-level inputs and drives CMOS outputs, making it a direct fit for digital clock synthesis and frequency tracking in 2V to 6V systems. The 38 MHz maximum frequency sets the upper bound for the loop bandwidth — beyond that, the phase detector gain rolls off and the VCO linearity degrades.
Frequency ceiling and loop design considerations
At 38 MHz max, this PLL is suited for clock generation up to that frequency, but the practical loop bandwidth is lower — typically 1/10th of the VCO frequency to keep the loop stable and the phase noise within the lock-detector threshold. The 1:2 input-to-output ratio means the VCO output can be divided by two internally, which helps when the reference is slower than the target clock.
Temperature range and deployment environment
Rated for -55°C to 125°C, the CD74HC7046AM covers military and industrial extremes. The wide temperature grade means the PLL's phase-detector gain and VCO tuning range are characterised across the full span — critical for avionics, downhole instrumentation, or outdoor telecom where the ambient temperature varies by 150°C or more. The 16-SOIC package (3.90 mm width) is a standard surface-mount footprint, reflow-compatible with typical Pb-free profiles.
Production status and sourcing posture
For BOM planning, the active status means no immediate end-of-life risk, but the 74HC family is mature — confirm lead time and pricing against your quantity at quote time.