MC74HC4046ADR2G

Clock Generators, PLLs, Frequency Synthesizers Overview

The MC74HC4046ADR2G is a high-performance silicon-gate CMOS phase-locked loop (PLL) manufactured by onsemi. It integrates three phase comparators, a 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 circuits functional down to 2.0 V. It features an operating temperature range from -55°C to +125°C and is housed in a SOIC-16 package. The component provides drive capability for 10 LSTTL loads and includes diode protection on all inputs.

Clock Generators, PLLs, Frequency Synthesizers Feature Summary

• Integrates Phase Comparator 1 (XOR gate), Phase Comparator 2 (digital memory network), and Phase Comparator 3 (edge-triggered sequential detector).
• Includes a linear Voltage-Controlled Oscillator (VCO) with frequency determined by external R1, R2, and C1 components.
• Features a unity gain op-amp output (DEMOUT) for buffered access to the VCO input voltage without loading the loop filter.
• Provides an Inhibit input (INH) to disable the VCO and op-amps for minimized standby power consumption.

Clock Generators, PLLs, Frequency Synthesizers Applications

• FM and FSK modulation and demodulation
• Frequency synthesis and multiplication
• Tone decoding and data synchronization
• Voltage-to-frequency conversion

Clock Generators, PLLs, Frequency Synthesizers Procurement Notes

Verify the ordering suffix 'R2G' corresponds to the SOIC-16 tape and reel packaging containing 2500 units per reel. Confirm that the 'G' designation indicates a lead-free package compliant with RoHS standards. Ensure the procurement source provides the official datasheet revision 8 documentation for accurate electrical parameter verification.

Clock Generators, PLLs, Frequency Synthesizers Selection Notes

Select this component when a CMOS-compatible PLL with multiple phase detection options is required. Phase Comparator 1 is suitable for signals with 50% duty cycles, while Phase Comparator 2 offers zero-degree phase shift locking independent of duty cycle. Verify that the external timing components (R1, R2, C1) fall within the specified ranges for the target center frequency and lock range.

Clock Generators, PLLs, Frequency Synthesizers Part Context

This part belongs to the MC74HC4046A family of phase-locked loops. It is functionally similar to the older MC14046 metal-gate CMOS device but utilizes high-speed silicon-gate technology. The HC4046A series maintains compatibility with standard CMOS outputs and can interface with LSTTL outputs using pullup resistors.

Clock Generators, PLLs, Frequency Synthesizers Replacement Considerations

Direct substitutes include other variants within the MC74HC4046A family, such as MC74HC4046ADG (SOIC-16 rail) or MC74HC4046AN (PDIP-16). Cross-manufacturer equivalents like the NXP 74HC4046 may be considered if pinout and electrical specifications are verified against the onsemi datasheet.

Clock Generators, PLLs, Frequency Synthesizers FAQ

What is the function of the DEMOUT pin?

The DEMOUT pin provides the output of a unity gain operational amplifier that buffers the VCOIN signal. This allows the VCO input voltage to be accessed externally without degrading loop performance due to loading effects.

How does Phase Comparator 2 differ from Phase Comparator 1?

Phase Comparator 1 is an XOR gate requiring 50% duty cycle inputs and maintaining a 90-degree phase shift at center frequency. Phase Comparator 2 uses leading-edge sensing logic to maintain a 0-degree phase shift regardless of duty cycle and enters a high-impedance state when locked.

What is the effect of the INH input?

When the Inhibit (INH) input is held high, it disables the VCO and all internal operational amplifiers. This feature is designed to minimize standby power consumption when the internal VCO is not in use.