NXP Semiconductors 74HCT9046AN,112

Overview

74HCT9046AN,112 from NXP Semiconductors is a high-speed Si-gate CMOS phase-locked loop (PLL) IC featuring a band gap–controlled voltage-controlled oscillator (VCO), dual phase comparators (EXCLUSIVE-OR and edge-triggered JK flip-flop), and ±10% center frequency tolerance at VCC = 5.5 V. It operates from 4.5 V to 5.5 V, supports up to 17 MHz typical center frequency, and delivers glitch-free VCO operation down to very low frequencies - used in FM demodulation, video picture-in-picture synthesis, and motor-speed control.

For engineers reviewing the 74HCT9046AN,112 datasheet, 74HCT9046AN,112 pinout, 74HCT9046AN,112 application, or 74HCT9046AN,112 equivalent, key selection factors include its current-source charge pump output (PC2_OUT), on-chip band gap reference for supply/temperature stability, dual comparator selection logic via RB pin, and DIP16 package compatibility with legacy through-hole designs.

Technical Context

The 74HCT9046AN,112 implements a second-order PLL using either PC1 (XOR-based, 50% duty cycle input required) or PC2 (edge-triggered JK flip-flop with zero-dead-zone current-source charge pump). PC2's output current (Icp = 17 × 2.5 V / Rbias) is set by an external bias resistor (Rbias = 25 kΩ–250 kΩ) connected between pin RB and GND, enabling precise loop gain control independent of supply voltage.

VCO frequency is set by external R1/R2 and C1 components, with VCO_IN voltage range specified as 1.1 V to 4.4 V across VCC = 4.5–5.5 V. The inhibit (INH) input disables the entire circuit at HIGH to minimize standby current (≤160 µA at VCC = 5.5 V), differing from the 74HCT4046A's partial disable behavior.

Key Specifications

Pinout & Package

74HCT9046AN,112 is supplied in a plastic dual in-line package (DIP16) with 300-mil body width, suitable for through-hole mounting and prototyping. Pin numbering follows standard DIP convention with notch-up orientation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PLL applications.

Compared with 74HCT4046AD,653 and CD74HC4046M96, the 74HCT9046AN,112 uniquely delivers supply- and temperature-stable center frequency via band gap reference and zero-dead-zone current-source PC2 - making it the only choice for high-fidelity FM demodulation and low-jitter video clock synthesis in industrial temperature ranges.

Availability

74HCT9046AN,112 is available at Aetrix Electronics and suitable for FM demodulation, video picture-in-picture synthesis, and motor-speed control requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74HCT9046AN,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 focused on secure connectivity solutions for automotive, industrial, and IoT applications.

The 74HCT9046AN,112 belongs to NXP's legacy HCT logic and timing portfolio, designed specifically for high-reliability analog-intensive PLL applications where supply/temperature stability and low-jitter performance are critical.

FAQ

What is the function of pin RB on the 74HCT9046AN,112?

Pin RB on the 74HCT9046AN,112 serves as the bias resistor terminal that determines PLL operating mode. When connected to GND via Rbias (25 kΩ–250 kΩ), it enables Phase Comparator 2 (PC2) and configures PC1_OUT/PCP_OUT (pin 2) as a lock-detect output. If left unconnected or tied to VCC, the device defaults to Phase Comparator 1 (PC1) operation. This hardware-selectable mode eliminates need for configuration registers or external logic.

How does the 74HCT9046AN,112 achieve ±10% center frequency tolerance?

The 74HCT9046AN,112 achieves ±10% center frequency tolerance through an integrated on-chip band gap reference that stabilizes all internal voltage references. Unlike earlier PLLs relying on VCC-dependent thresholds, this reference fixes the VCO offset voltage at 2.5 V - making frequency setting insensitive to supply voltage variation and reducing thermal drift across −40 °C to +125 °C.

Can the 74HCT9046AN,112 be used with AC-coupled input signals?

Yes, the 74HCT9046AN,112 supports AC-coupled inputs on SIG_IN and COMP_IN pins due to its self-biasing input amplifier architecture. A series capacitor blocks DC while the internal bias network centers the small-swing signal within the linear region of the amplifier - enabling reliable operation with audio tones, DTMF signals, or other low-amplitude waveforms without external biasing components.

What is the purpose of the dual GND pins (pins 1 and 8) on the 74HCT9046AN,112?

Pins 1 and 8 on the 74HCT9046AN,112 provide separate ground returns for the phase comparator section and VCO section respectively. This isolation minimizes coupling of digital switching noise from comparators into the sensitive analog VCO control path - a key enabler for high-performance FM demodulation at frequencies ≥10 MHz and low-distortion motor-speed feedback loops.

Does the 74HCT9046AN,112 support lock detection functionality?

Yes, the 74HCT9046AN,112 provides lock detection via pin 2 (PC1_OUT/PCP_OUT) when operated in PC2 mode. When RB is connected to GND, internal logic reconfigures this pin as PCP_OUT - delivering minimum-width pulses (equal to the 15 ns PC2 overlap time) during locked condition. This signal can directly drive microcontroller interrupts or status LEDs without additional conditioning circuitry.