MM74HC4046SJX

Overview

The MM74HC4046SJX is a CMOS Phase Lock Loop utilizing advanced silicon-gate technology. It integrates a low-power linear voltage-controlled oscillator (VCO), a source follower, and three phase comparators with common signal and comparator inputs. The device operates on a supply voltage of 2 V to 6 V within an operating temperature range of -40°C to +85°C. Key electrical specifications include a maximum VCO frequency of 12 MHz at 4.5 V and fast comparator response times of 25 ns for Comparator I and III, and 30 ns for Comparator II.

Feature Summary

• Integrates a low-power linear VCO, source follower, and three distinct phase comparators (XOR, edge-sensitive, SR flip-flop).
• Maximum VCO operating frequency reaches 12 MHz at VCC = 4.5 V.
• Fast comparator response times: 25 ns for Comparator I and III; 30 ns for Comparator II.
• Signal input features self-biasing amplifier allowing AC coupling or direct logic level connection.

Applications

• Frequency synthesis circuits requiring stable clock generation.
• FM demodulation systems utilizing the VCO linearity and demodulator output.
• Clock recovery applications in digital communication links.

Procurement Notes

Verify that the ordering code includes the 'SJ' suffix to confirm the SOP package variant. Confirm the 'X' suffix indicates tape and reel packaging if required by assembly equipment. Check current availability status as distribution may vary by region.

Selection Notes

Select this component when a high-speed CMOS PLL is needed with multiple phase detector options. Ensure external components R1, R2, and C1 are chosen to set the desired center frequency and lock range according to the typical performance curves. Verify that the 16-lead SOP package dimensions fit the PCB layout constraints.

Part Context

This part belongs to the MM74HC4046 family of CMOS Phase Lock Loops. It is functionally similar to the CD4046 but replaces the Zener diode with a third phase comparator. Other variants in the series include the M (SOIC), N (PDIP), and MTC (TSSOP) package options.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. Cross-reference with other manufacturers' 74HC4046 devices only if pin compatibility and electrical parameters are verified against the official datasheet.

FAQ

What is the difference between the three phase comparators?

Comparator I is an XOR gate providing 90-degree phase shift at center frequency. Comparator II is an edge-sensitive network providing 0-degree phase shift and a 3-state output. Comparator III is an SR flip-flop suitable for pulse inputs.

How is the VCO frequency determined?

The VCO operating frequency is set by three external components connected to pins C1A, C1B, R1, and R2. R1 controls the lock range, while R2 can be used to set an offset frequency.

What is the purpose of the source follower?

The source follower allows monitoring of the VCO input voltage without loading the loop filter. It connects to the Demodulator output (Pin 10) and typically requires a resistor to ground.