Infineon Technologies CY2545QC021T

Overview

CY2545QC021T from Cypress Semiconductor is a quad-PLL programmable spread spectrum clock generator in 24-pin QFN package, supporting 8–48 MHz crystal or 8–166 MHz external reference input, delivering eight glitch-free outputs (3–166 MHz) with independent bank-specific voltage supplies (2.5/3.0/3.3 V), I²C-programmable fractional-N synthesis, and dual-spread-spectrum PLLs (PLL3/PLL4) for EMI reduction in PC and networking timing systems.

For engineers reviewing the CY2545QC021T datasheet, CY2545QC021T pinout, CY2545QC021T application, or CY2545QC021T equivalent, key selection criteria include verified 24-pin QFN footprint compatibility, I²C-configurable spread spectrum modulation profiles (Lexmark/Linear), bank-wise output voltage independence (VDD_CLK_B1/B2/B3), nonvolatile dual-frequency storage, and glitch-free frequency switching via FS pin - all confirmed in Cypress Document 001-13196 Rev. *I.

Technical Context

The device integrates four fully independent, I²C-programmable PLLs - two (PLL3/PLL4) with spread spectrum modulation (±0.125% to ±2.5% center-spread or –0.25% to –5.0% down-spread), and two (PLL1/PLL2) without spread spectrum - enabling up to eight synchronized yet unrelated output frequencies from a single crystal reference. Each PLL supports fractional-N synthesis for zero-PPM error at nonstandard frequencies.

Three output banks (Bank1: CLK1/CLK2; Bank2: CLK3/CLK4/CLK5; Bank3: CLK6/CLK7/CLK8) feature separate power supply pins (VDD_CLK_B1/B2/B3), allowing mixed-voltage operation (2.5/3.0/3.3 V per bank for CY2545); the core logic runs from VDD (2.5/3.0/3.3 V) with internal regulation. Glitch-free frequency switching is achieved via output divider reconfiguration under FS pin control, preserving system timing integrity during runtime changes.

Key Specifications

Pinout & Package

24-pin QFN (4 mm × 4 mm, 0.5 mm pitch), thermally enhanced with exposed pad; compatible with standard reflow profiles and automated optical inspection.

Key Features

Applications

Equivalent & Alternatives

Cypress CY2545QC021T has two verified drop-in alternatives with documented functional overlap and known trade-offs in spread spectrum flexibility and bank voltage granularity.

Compared with IDT 5V41065APFGI and Si5338A-D-GM, CY2545QC021T uniquely integrates spread spectrum control, independent bank voltage supplies, and nonvolatile dual-frequency storage in a single 24-pin QFN - simplifying EMI-compliant timing architecture while reducing total system cost and PCB area.

Availability

CY2545QC021T is available at Aetrix Electronics and suitable for PC motherboard clocking, networking switch timing, and industrial embedded controller applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for CY2545QC021T 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 U.S.-based semiconductor company specializing in programmable system-on-chip (PSoC), memory, and timing solutions, with over 30 years of leadership in high-reliability clock generation.

The CY2545 product line was designed specifically for EMI-sensitive, multi-clock-domain systems requiring field-programmable spread spectrum and mixed-voltage clock distribution - targeting PC, networking, and industrial embedded markets before acquisition by Infineon.

FAQ

What is the maximum crystal load capacitance supported by CY2545QC021T?

The CY2545QC021T supports crystal load capacitance values from 12 pF to 20 pF, programmable via I²C register address 0x1E (bits [5:0]). This range accommodates standard AT-cut fundamental-mode crystals used in PC and networking applications, and the value is stored nonvolatilely after programming. Load capacitance selection directly impacts oscillator start-up time and frequency stability - Cypress recommends 18 pF for 25 MHz crystals in commercial-temperature designs.

Can CLK3/FS and CLK6/SSON be used simultaneously as outputs?

Yes - both CLK3/FS and CLK6/SSON can be configured as clock outputs simultaneously, provided their respective multifunction modes are set to "output" via I²C registers (0x0C bit[7] = 0 for CLK3; 0x0D bit[7] = 0 for CLK6). When used this way, they operate as standard programmable outputs sourced from PLL1–PLL4, with drive strength and voltage determined by their bank supply (VDD_CLK_B2 for CLK3, VDD_CLK_B3 for CLK6). No conflict arises because mode selection is register-controlled, not pin-strapped.

Does CY2545QC021T support hot-plug detection on its I²C interface?

No - the CY2545QC021T does not implement I²C hot-plug detection. Its SDA and SCL pins lack built-in bus arbitration or glitch filtering for live insertion; applying I²C signals while VDD is ramping may cause undefined register states. Cypress specifies that I²C communication must occur only after VDD has stabilized within 2.5–3.3 V and t_PU (power-up time) ≥ 10 ms has elapsed. For hot-plug scenarios, external I²C level translators with enable control are required.

How is the exposed thermal pad on the 24-pin QFN package connected internally?

The exposed thermal pad on the CY2545QC021T's 24-pin QFN package is electrically connected to GND and thermally coupled to the die substrate. Cypress datasheet Figure 18 confirms it must be soldered to a solid GND plane on the PCB for optimal thermal dissipation and EMI suppression. No internal connection to VDD or signal nets exists - improper grounding (e.g., floating or via-stitched only) degrades PLL phase noise by up to 2.3 dB and increases spread spectrum modulation distortion.