NXP Semiconductors 74HC4046AD/AUJ

Overview

74HC4046AD/AUJ from Nexperia is a high-speed CMOS phase-locked loop (PLL) IC with integrated linear voltage-controlled oscillator (VCO) and three selectable phase comparators (EXOR, edge-triggered J-K, and RS flip-flop). It operates from 3.0 V to 6.0 V (VCO section), delivers up to 17 MHz center frequency at V_CC = 4.5 V, and supports FM demodulation, frequency synthesis, and motor-speed control.

For engineers reviewing the 74HC4046AD/AUJ datasheet, 74HC4046AD/AUJ pinout, 74HC4046AD/AUJ application, or 74HC4046AD/AUJ equivalent, this device offers verified VCO linearity, low temperature drift (0.15 %/K), zero-voltage offset buffering, and dual-section supply flexibility (2.0–6.0 V digital / 3.0–6.0 V VCO) for precision analog-digital PLL design.

Technical Context

The 74HC4046AD/AUJ implements a second-order PLL using external passive R-C networks (R1/R2 + C1) for VCO tuning and low-pass filtering. Its VCO achieves excellent linearity via linear op-amp techniques and provides a demodulator output (DEM_OUT) that mirrors VCO_IN voltage without threshold drop-enabling accurate feedback without level-shifting.

All three phase comparators share a common signal input amplifier and comparator input. PC1 requires 50 % duty-cycle inputs for maximum lock range; PC2 functions as an up-down frequency/phase detector with 3-state output and lock-indicating PCP_OUT; PC3 uses positive-edge-triggered RS logic and yields higher ripple but wider phase sensitivity (0°–360°).

Key Specifications

Pinout & Package

74HC4046AD/AUJ is supplied in SO16 (SOT109-1) plastic small outline package, 16-pin, 3.9 mm body width, JEDEC-compliant.

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 74HC4046AD/AUJ uniquely combines 17 MHz capability, DEM_OUT voltage mirroring, and three-phase comparator flexibility-making it optimal for high-fidelity FM demodulation and precision V/f conversion where linearity and lock reliability are critical.

Availability

74HC4046AD/AUJ is available at Aetrix Electronics and suitable for FM demodulation, frequency synthesis, and motor-speed control applications requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature.

Supply support for 74HC4046AD/AUJ 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

Nexperia is a global semiconductor expert delivering high-performance, reliable logic, analog, and MOSFET solutions for automotive, industrial, and consumer markets.

The 74HC4046AD/AUJ belongs to Nexperia's HC logic family, engineered for high-speed, low-power phase-locked loop applications demanding precision VCO linearity, robust noise immunity, and flexible comparator architecture.

FAQ

What is the maximum center frequency achievable with the 74HC4046AD/AUJ?

The 74HC4046AD/AUJ achieves a typical center frequency of 17 MHz at V_CC = 4.5 V with R1 = 3 kΩ, R2 = open, and C1 = 40 pF. At V_CC = 6.0 V, the center frequency increases to 21 MHz under identical conditions. These values are measured and specified in Nexperia's official datasheet Rev. 7 (May 2024), Table 7.

How does the DEM_OUT pin function in the 74HC4046AD/AUJ?

The DEM_OUT pin on the 74HC4046AD/AUJ provides a buffered, unity-gain replica of the VCO_IN voltage-unlike conventional VCOs whose demodulator output drops by one threshold voltage. This zero-offset behavior (±20 mV max at V_CC = 4.5 V) ensures accurate feedback in closed-loop configurations. A series resistor (50–300 kΩ) must be added from DEM_OUT to GND if used; otherwise, it should remain open.

Which phase comparator should I use for noisy input signals with the 74HC4046AD/AUJ?

For noisy input signals, Phase Comparator 1 (PC1) is recommended in the 74HC4046AD/AUJ because its XOR architecture maintains lock even with significant input jitter or harmonics near the VCO center frequency. PC1's capture range can match its lock range when paired with an optimized low-pass filter, making it more robust than PC2 or PC3 under high-noise conditions.

Can the 74HC4046AD/AUJ operate with separate supplies for its digital and VCO sections?

No-the 74HC4046AD/AUJ has a single VCC pin (pin 16) powering both digital logic (operable from 2.0 V to 6.0 V) and the VCO section (requiring 3.0 V to 6.0 V). While the sections have different minimum voltage thresholds, they share the same supply rail. The VCO will not function below 3.0 V, even if the digital inputs remain valid down to 2.0 V.

What external components are mandatory for basic VCO operation in the 74HC4046AD/AUJ?

For basic VCO operation, the 74HC4046AD/AUJ requires one external capacitor (C1, 40 pF minimum) connected between pins C1A (6) and C1B (7), and one external resistor (R1, 3 kΩ to 300 kΩ) connected between pin R1 (11) and GND (8). R2 (pin 12) is optional and used only when a frequency offset is needed. The parallel value of R1 and R2 must exceed 2.7 kΩ per datasheet guidance.