MC74HC4046ADT

Clock Generators, PLLs, Frequency Synthesizers Overview

The MC74HC4046ADT is a high-performance silicon-gate CMOS phase-locked loop (PLL) manufactured by onsemi. It integrates three distinct phase comparators, a linear voltage-controlled oscillator (VCO), and a unity gain operational amplifier (DEMOUT). The device operates within a supply voltage range of 3.0 V to 6.0 V, with non-VCO functionality supported down to 2.0 V. It features an operating temperature range from -55°C to +125°C and is housed in a TSSOP-16 package (DT suffix). Key electrical characteristics include a maximum quiescent current of 80 μA when the VCO is disabled and input drive capability equivalent to 10 LSTTL loads.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Integrates three phase comparators: XOR gate (PC1), edge-sensitive digital network (PC2), and RS flip-flop (PC3).
• Linear Voltage-Controlled Oscillator (VCO) with frequency determined by external R1, R2, and C1 components.
• Unity gain op-amp DEMOUT provides buffered access to the VCOIN signal without loading the loop filter.
• Inhibit input disables the VCO and all op-amps to minimize standby power consumption.

Clock Generators, PLLs, Frequency Synthesizers Applications

• FM and FSK modulation and demodulation circuits.
• Frequency synthesis and multiplication systems.
• Data synchronization and conditioning applications.
• Voltage-to-frequency conversion designs.
• Motor speed control loops.

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify the DT suffix indicates the TSSOP-16 package configuration. Confirm RoHS compliance status as Pb-Free packages are available for this series. Check current manufacturing status, as some variants may be obsolete or subject to production changes. Ensure the specific revision level matches design requirements.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select Phase Comparator 1 for noise rejection with 50% duty cycle inputs. Use Phase Comparator 2 for zero phase shift locking independent of duty cycle. Choose Phase Comparator 3 for positive-edge triggering where duty cycle is immaterial. Ensure external R1/R2/C1 values maintain VCO linearity and stay within specified resistance ranges (3.0 kΩ to 300 kΩ).

Clock Generators, PLLs, Frequency Synthesizers Part Context

This component belongs to the 74HC4046A family of high-speed CMOS logic devices. It is functionally similar to the older MC14046 metal-gate CMOS device but offers improved operating speeds comparable to LSTTL. The HC4046A inputs are compatible with standard CMOS outputs and, with pull-up resistors, with LSTTL outputs.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Direct substitutes include MC74HC4046ADG (SOIC-16 package) and MC74HC4046AN (PDIP-16 package). Other manufacturers such as Texas Instruments (CD74HC4046) and Nexperia (74HC4046) offer pin-compatible alternatives with similar electrical specifications.