NXP Semiconductors 74HC7046AD,112

Overview

74HC7046AD,112 from NXP Semiconductors (formerly Philips) is a high-speed CMOS phase-locked-loop IC with integrated lock detector, VCO, and dual phase comparators (XOR and edge-triggered JK). It delivers 17 MHz typical VCO center frequency at 5 V, 50% VCOOUT duty factor (±1%), and operates across 2.0–6.0 V digital supply and 3.0–6.0 V VCO supply. It is used in FM demodulation, tone decoding, and data synchronization circuits.

For engineers reviewing the 74HC7046AD,112 datasheet, 74HC7046AD,112 pinout, 74HC7046AD,112 application, or 74HC7046AD,112 equivalent, key selection criteria include VCO linearity (≤0.4% at 4.5 V), lock detector output behavior (active-HIGH LD at pin 1), dual comparator selection (PC1 for noise immunity, PC2 for frequency acquisition), and external component dependencies (R1, R2, C1, CLD).

Technical Context

The 74HC7046AD,112 implements a second-order PLL using either an XOR-based phase comparator (PC1) with 50% duty-cycle input requirement and ripple suppression at 2× input frequency, or an edge-triggered JK flip-flop comparator (PC2) enabling frequency/phase detection independent of duty cycle and offering 3-state output for low filter power dissipation. Its linear op-amp buffered VCO achieves minimal frequency drift (0.15%/K at 4.5 V) and zero voltage offset at DEMOUT.

VCO frequency is set by external R1/C1 (or R1+R2/C1), with center frequency tunable from 7–21 MHz depending on supply and component values. The inhibit input (INH) disables both VCO and demodulator to reduce standby current, while DEMOUT provides a buffered replica of VCOIN voltage-enabling direct low-pass filter interfacing without threshold loss.

Key Specifications

Pinout & Package

74HC7046AD,112 is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package, compliant with JEDEC MS-012AC, body size 10.0 × 4.4 mm, lead pitch 1.27 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar phase-locked-loop applications.

Compared with CD4046BE and SN74LV4046A, the 74HC7046AD,112 uniquely combines 17 MHz VCO performance, buffered DEMOUT, integrated lock detector with programmable timing, and dual comparator selection - making it optimal for mid-frequency, noise-sensitive, and self-contained PLL designs.

Availability

74HC7046AD,112 is available at Aetrix Electronics and suitable for FM demodulation, tone decoding, and data synchronization requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and voltage.

Supply support for 74HC7046AD,112 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader specializing in secure connectivity solutions for automotive, industrial, and IoT applications.

The 74HC7046AD,112 belongs to NXP's legacy HC logic family and was designed for general-purpose analog-digital PLL applications demanding high linearity, low drift, and flexible comparator selection in cost-sensitive industrial and consumer systems.

FAQ

What is the maximum VCO center frequency achievable with 74HC7046AD,112 under standard conditions?

The 74HC7046AD,112 achieves a typical VCO center frequency of 17 MHz at VCC = 4.5 V, R1 = 3 kΩ, and C1 = 40 pF. Under optimized conditions (VCC = 6.0 V, R1 = 3 kΩ, C1 = 40 pF), the datasheet specifies up to 21 MHz. This value is confirmed in the Quick Reference Data table (page 4) and Fig.17. Operation beyond 21 MHz is not characterized and may compromise linearity or lock range.

How does the DEMOUT pin function in the 74HC7046AD,112, and why is it different from conventional PLL demodulators?

The DEMOUT pin of the 74HC7046AD,112 provides a buffered, op-amp replicated voltage equal to VCOIN - unlike conventional demodulators where DEMOUT is typically one threshold voltage lower. This eliminates voltage loss in the feedback path, preserving loop gain accuracy and simplifying low-pass filter design. As stated in the General Description (page 2), "DEMOUT voltage equals that of the VCO input," and offset is limited to ±20 mV at 4.5 V.

Can the 74HC7046AD,112 operate with separate supplies for the digital and VCO sections?

No - the 74HC7046AD,112 uses a single VCC supply (pin 16) for all internal sections including digital logic, phase comparators, lock detector, and VCO control circuitry. However, the VCO analog core itself operates correctly only when VCC ≥3.0 V, while the digital section remains functional down to 2.0 V. This is explicitly defined in the Recommended Operating Conditions table (page 9) under "DC supply voltage if VCO section is not used."

What external components are mandatory for basic 74HC7046AD,112 PLL operation, and what are their roles?

Four external components are mandatory: C1 (timing capacitor between pins 6 and 7) sets VCO frequency range; R1 (resistor from pin 11 to GND) establishes base VCO bias current; CLD (capacitor from pin 15 to GND) configures lock detector response; and a low-pass filter (R3/C2) between PC1OUT/PC2OUT and VCOIN completes the loop. These are specified in the General Description (page 2) and APPLICATION INFORMATION (page 27).

Does the 74HC7046AD,112 support both AC- and DC-coupled signal inputs, and how is coupling selected?

Yes - the 74HC7046AD,112 supports both coupling methods at SIGIN (pin 14). DC coupling is used for logic-level signals meeting HC input thresholds (VIH ≥1.5 V, VIL ≤0.8 V at 2.0 V); capacitive coupling is required for small-swing analog signals (as low as 9 mV_p-p). The self-biasing input amplifier automatically centers small signals within its linear region, eliminating need for external bias networks. This is detailed in the General Description (page 2) and AC Characteristics table (page 14).