SY89464UMY-TR

Clock Buffers, Drivers Overview

The SY89464UMY-TR is a Precision LVPECL fanout buffer featuring a 2:1 differential input multiplexer with Runt Pulse Eliminator (RPE) and Fail-Safe Input (FSI). It provides ten LVPECL outputs from two inputs, supporting frequencies up to 2.0 GHz. The device operates on a 2.5V ±5% or 3.3V ±10% supply within an industrial temperature range of –40°C to +85°C. Key electrical parameters include propagation delays under 1100ps, output rise/fall times below 220ps, and jitter specifications of less than 1ps RMS random and cycle-to-cycle jitter. It utilizes a 44-pin QFN package.

Clock Buffers, Drivers Feature Summary

• Integrates a 2:1 MUX with Runt Pulse Eliminator for glitchless redundant clock switchover
• Fail-Safe Input prevents metastable conditions when selected input amplitude drops below 100mV
• Features unique internal termination architecture accepting AC- or DC-coupled signals as small as 100mV without external level shifting
• Ultra-low jitter design with less than 1ps RMS random jitter and less than 10ps PP total jitter

Clock Buffers, Drivers Applications

• Redundant clock switchover systems
• Fail-safe clock protection circuits
• Enterprise servers requiring high reliability
• Test and measurement equipment

Clock Buffers, Drivers Procurement Notes

Verify the component origin, as the datasheet identifies Micrel Inc. as the manufacturer while the model prefix suggests Microchip Technology acquisition. Confirm that the TR suffix correctly denotes the Tape and Reel packaging format specified in the ordering information. Ensure compatibility with the required 2.5V or 3.3V power supply rails and verify the 44-pin QFN footprint matches the PCB layout.

Clock Buffers, Drivers Selection Notes

Select this component when designing systems requiring seamless switching between two clock sources without generating runt pulses. The internal termination allows direct interfacing with CML, PECL, or LVDS signals. Ensure the CAP pin is properly configured with a capacitor to enable the Power-On Reset function if RPE operation is desired. Verify that the operating frequency remains within the guaranteed 1.5GHz to 2.0GHz range for optimal AC performance.

Clock Buffers, Drivers Part Context

The SY89464U belongs to the Precision Edge product line originally developed by Micrel Inc. The 'UMY' suffix indicates the 44-pin QFN package variant, while 'TR' specifies the tape and reel shipping configuration. This part is distinct from the SY89465U, which utilizes LVDS outputs instead of LVPECL. The device is designed for high-speed digital applications requiring precise timing and signal integrity.

Clock Buffers, Drivers Replacement Considerations

The SY89465U is a related component offering similar functionality but with LVDS outputs instead of LVPECL. When substituting, verify that the receiving circuitry supports LVDS signaling levels. No other direct parameter-equivalent substitutes are confirmed in the provided documentation.

Clock Buffers, Drivers FAQ

How does the Runt Pulse Eliminator function during clock switchover?

The RPE circuit ensures glitchless switchover by preventing short cycles or runt pulses. It switches in three stages: following the primary clock, holding low for a limited number of secondary clock pulses, and then following the secondary clock.

What happens if the selected input clock fails to a DC voltage?

The Fail-Safe Input (FSI) circuit detects if the differential input voltage drops below 100mV. It latches the output to the last valid clock state, preventing oscillations or metastable conditions.

Can the device interface with AC-coupled inputs?

Yes, the unique internal termination architecture accepts both AC- and DC-coupled differential signals. The VREF-AC pins provide biasing for AC-coupled inputs and should be connected to the respective VT pins.