Infineon Technologies CY29421FLXIT

Overview

CY29421FLXIT from Infineon Technologies (formerly Cypress) is a high-performance programmable fractional-N PLL-based oscillator with integrated crystal, supporting differential output standards (LVPECL/LVDS/HCSL/CML), 15 MHz to 2.1 GHz frequency range, ±50–±275 ppm VCXO total pull range, and 150 fs typical integrated jitter (12 kHz–20 MHz). It operates from 1.8 V/2.5 V/3.3 V supplies across –40 °C to +105 °C and targets precision timing in OTN, wireless infrastructure, and high-speed data converters.

For engineers reviewing the CY29421FLXIT datasheet, CY29421FLXIT pinout, CY29421FLXIT application, or CY29421FLXIT equivalent, key selection criteria include its field-programmable I²C interface, guaranteed low-jitter performance at >150 MHz outputs, VCXO linearity over temperature/voltage, and 8-pin LCC 5.0 × 3.2 mm package compatibility with clock distribution and synchronous timing systems.

Technical Context

The device integrates a fractional-N LC-VCO PLL with fully embedded crystal reference and digital configuration via I²C, enabling factory or field reprogramming of output frequency, output standard, OE polarity, and VCXO parameters (Kv, TPR, modulation bandwidth). Its architecture separates volatile NVMCopy memory (for runtime updates) from one-time-programmable eFuse storage.

It supports Small Change (±500 ppm glitch-free frequency update) and Large Change (full PLL recalibration) modes via I²C, with default 7-bit address 0x55, Fast Mode (400 kbps) timing, and power-on reset behavior governed by LOCK state (00 = Command Wait, 10/01 = Active). VCXO control voltage (VC) input is present on CY29422 variants but not CY29421 - this part uses OE-only control.

Key Specifications

Pinout & Package

Package: 8-pin LCC (Leadless Chip Carrier), 5.0 mm × 3.2 mm body size, surface-mount, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5341-B-GM and ICS8430I-01T, CY29421FLXIT uniquely balances single-output simplicity, field programmability, wide VCXO range, and compact 5.0 × 3.2 mm LCC footprint - making it optimal for upgradeable timing in space-constrained telecom and instrumentation modules.

Availability

CY29421FLXIT is available at Aetrix Electronics and suitable for OTN line cards, 5G baseband units, high-speed test equipment, and synchronous industrial Ethernet switches requiring stable component supply across extended temperature and long product lifecycles.

Supply support for CY29421FLXIT 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

Infineon Technologies is a global semiconductor leader headquartered in Munich, Germany, specializing in power systems, sensors, and connectivity solutions for automotive, industrial, and communications markets.

CY29421FLXIT belongs to Infineon's programmable clock oscillator product line, designed specifically for high-reliability, low-jitter timing in next-generation optical transport, wireless infrastructure, and precision instrumentation where field configurability and thermal stability are critical.

FAQ

What output standards does CY29421FLXIT support, and how are they selected?

CY29421FLXIT supports LVPECL, LVDS, HCSL, and CML differential output standards. Selection is performed via I²C register writes to the Output Standard field in Common Device Configuration memory (address range 50h–57h). The setting persists in volatile NVMCopy after power-on reset and can be changed dynamically without reprogramming OTP. No hardware modification or external components are required.

Does CY29421FLXIT require an external crystal, or is it fully integrated?

CY29421FLXIT is a fully integrated crystal oscillator: it contains a monolithic fixed-frequency crystal resonator inside the 5.0 × 3.2 mm LCC package. No external crystal, load capacitors, or loop filter components are needed - the device implements a fractional-N PLL with integrated LC-VCO referenced to the internal crystal, simplifying PCB layout and reducing bill-of-materials.

How is VCXO functionality implemented on CY29421FLXIT, and what is its tuning range?

CY29421FLXIT implements VCXO by modulating the VCO frequency using an analog control voltage applied to the VC pin (pin 1 on CY29422 variants). However, CY29421FLXIT is the OE-only variant and does not expose the VC pin - its VCXO function is disabled. For VCXO capability, CY29422FLXIT must be used, offering programmable TPR from ±50 ppm to ±275 ppm with linear Kv slope and stable performance over temperature and voltage.

Can CY29421FLXIT be reprogrammed in-system, and what tools are required?

Yes, CY29421FLXIT supports full in-system reprogramming via its I²C interface (400 kbps Fast Mode, default address 0x55). Configuration is performed using Cypress ClockWizard 2.1 software, which generates register maps for frequency, output standard, OE polarity, and other parameters. No external programmer hardware is needed - only a microcontroller or host processor with I²C capability and access to the SDA/SCL pins.