MM74HC4046SJ

Overview

The MM74HC4046SJ is a CMOS Phase Lock Loop (PLL) integrated circuit manufactured by onsemi, housed in a 16-lead Small Outline Package (SOP). It features a low-power linear voltage-controlled oscillator (VCO), a source follower, and three distinct phase comparators. The device operates within a supply voltage range of 2 V to 6 V and supports an operating temperature range of -40°C to +85°C. At 4.5 V, the maximum VCO frequency reaches 12 MHz, with comparator response times as fast as 25 ns.

Feature Summary

• Integrates a low-power linear VCO, source follower, and three phase comparators (XOR, edge-sensitive, SR flip-flop).
• Maximum VCO operating frequency of 12 MHz at VCC = 4.5 V.
• Fast comparator response: Comparator I and III at 25 ns; Comparator II at 30 ns (at VCC = 4.5 V).
• High linearity and temperature stability for the VCO section.

Applications

• Frequency synthesis circuits requiring stable clock generation.
• Demodulation systems utilizing the internal source follower output.
• Clock recovery applications leveraging the high-speed phase comparators.

Procurement Notes

Verify the specific SOP package variant (M16D) against design requirements. Confirm that the -40°C to +85°C industrial temperature range aligns with system constraints. Ensure supply voltage stays within the 2 V to 6 V operational limits during integration.

Selection Notes

Select this component when a single-chip PLL solution with multiple comparator options is required. The inclusion of both XOR and edge-sensitive comparators allows flexibility in loop filter design and noise rejection strategies. Verify pin compatibility if replacing legacy CD4046 designs, noting the removal of the Zener diode in favor of the third comparator.

Part Context

This part belongs to the MM74HC4046 family, which includes variants such as the M (SOIC), MTC (TSSOP), and N (PDIP) packages. The SJ suffix specifically denotes the 16-lead SOP package compliant with EIAJ TYPE II standards, measuring 5.3 mm in width.

Replacement Considerations

The MM74HC4046N (PDIP) and MM74HC4046M (SOIC) are direct package alternatives within the same family. For through-hole replacements, consider the PDIP version; for surface mount, the SOIC or TSSOP variants may be suitable depending on board space.

FAQ

What is the function of the Inhibit pin?

Applying a logic high to the Inhibit pin disables both the VCO and the source follower, placing the IC into a low-power state.

How does Phase Comparator II differ from Phase Comparator I?

Phase Comparator II is edge-sensitive and provides zero phase shift lock with a 3-state output, whereas Phase Comparator I is an XOR gate that requires a 50% duty cycle input and is more susceptible to harmonic locking.

What is the purpose of the Source Follower output?

The Source Follower allows monitoring of the VCO input voltage without loading the loop filter, facilitating easier tuning and analysis of the PLL characteristics.