Infineon Technologies CY2548QIT

Overview

CY2548QIT from Cypress Semiconductor is a quad-PLL programmable clock generator with spread spectrum capability, designed for high-precision timing synthesis in multi-clock domain systems. It delivers nine programmable LVCMOS outputs (3–166 MHz), supports 2.5 V/3.0 V/3.3 V reference input (CLKIN), features fractional-N synthesis for zero-PPM error, and integrates two spread-spectrum PLLs (PLL3/PLL4) for EMI reduction in PC and networking applications.

For engineers reviewing the CY2548QIT datasheet, CY2548QIT pinout, CY2548QIT application, or CY2548QIT equivalent, key selection criteria include its 24-pin QFN package, banked output voltage control (1.8 V/2.5 V/3.0 V/3.3 V per bank), glitch-free frequency switching via FS0–FS2, and one-time programmability for custom PLL configurations and SSC profiles.

Technical Context

The CY2548QIT implements four independent, fully integrated PLLs-two with spread spectrum (PLL3/PLL4) using Lexmark or Linear modulation-and accepts only external 2.5 V/3.0 V/3.3 V clock inputs (no crystal support). Its crossbar switch enables arbitrary routing of six clock sources (CLKIN, EXCLKIN, PLL1–PLL4) to nine outputs, with per-bank VDD_CLK_Bx supplies enabling mixed-voltage operation across three output banks.

Each output supports programmable drive strength and divider settings; frequency switching via FS0–FS2 is glitch-free due to synchronous divider reconfiguration. The device uses nonvolatile memory to store PLL coefficients, SSC parameters, load capacitance, and output configurations-enabling system-specific personalization without runtime programming.

Key Specifications

Pinout & Package

24-pin QFN (4 mm × 4 mm, 0.5 mm pitch), thermally enhanced with exposed thermal pad. Pin 1 marked by top-side dot; pins 1–12 on bottom row, 13–24 on top row (counterclockwise).

Key Features

Applications

Equivalent & Alternatives

CY2548QIT has two direct functional alternatives within the same family: CY2544QIT (crystal-input variant) and CY2546QIT (1.8 V-only variant). Differences center on input interface, voltage support, and internal regulation.

Compared with CY2544QIT and CY2546QIT, CY2548QIT uniquely supports 2.5–3.3 V external clock inputs without crystal, offers full banked voltage flexibility, and targets mid-to-high performance systems requiring EMI control and precise multi-frequency synthesis.

Availability

CY2548QIT is available at Aetrix Electronics and suitable for PC motherboard timing, networking switch ASIC clocking, and industrial PLC controller applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for CY2548QIT 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

Cypress Semiconductor (now part of Infineon Technologies) is a fabless semiconductor company specializing in programmable system-on-chip (PSoC), memory, and precision timing solutions for industrial, automotive, and communications markets.

CY2548QIT belongs to Cypress's Quad-PLL Clock Generator product line, engineered for systems demanding multiple synchronized, spread-spectrum-enabled clocks with zero-PPM synthesis accuracy and field-programmable flexibility.

FAQ

Does CY2548QIT support crystal input?

No. CY2548QIT lacks internal crystal oscillator circuitry-pins XIN and XOUT are unused (DNU). It accepts only 2.5 V/3.0 V/3.3 V external clock inputs on CLKIN and EXCLKIN. For crystal support, use CY2544QIT instead, which includes XIN/XOUT and operates with 8–48 MHz crystals.

What is the function of pin 23 (DNU) on CY2548QIT?

Pin 23 is designated DNU (Do Not Use) and has no internal connection. It must be left unconnected or tied to GND per Cypress layout guidelines-floating it may cause noise coupling. This pin is active only on CY2544/CY2546 variants (as XOUT), confirming CY2548's exclusive reliance on external clock inputs.

Can CY2548QIT generate exactly 100 MHz and 125 MHz simultaneously?

Yes. Using fractional-N synthesis in PLL1 and PLL2, CY2548QIT can independently generate 100.000 MHz and 125.000 MHz with zero PPM error. Each PLL drives separate outputs (e.g., CLK1 and CLK4), and the crossbar switch allows arbitrary source assignment-no shared dividers or frequency dependencies.

How is spread spectrum enabled or disabled on CY2548QIT?

Spread spectrum is controlled via the multifunction CLK7/SSON pin (pin 15). Driving this pin low disables SSC on PLL3/PLL4; driving it high enables SSC using the pre-programmed profile (Lexmark/Linear) and spread range stored in OTP memory. No runtime register writes are needed-activation is hardware-level and instantaneous.