SY89845UMG

Signal Switches, Multiplexers, Decoders Overview

The SY89845UMG is a Precision CML Runt Pulse Eliminator 2:1 MUX with 1:2 fanout and internal termination. It operates from a 2.5V ±5% or 3.3V ±10% supply, supporting frequencies up to 2.0 GHz. Propagation delay ranges from 390 ps to 840 ps depending on input swing. The device features ultra-low jitter (<1ps RMS random/cycle-to-cycle) and outputs 400mV CML signals with rise/fall times under 80 ps. It includes fail-safe input protection and is housed in a 24-pin QFN package.

Signal Switches, Multiplexers, Decoders Feature Summary

• Runt Pulse Eliminator (RPE) circuitry ensures glitch-free switchover between two clock sources without generating short cycles.
• Fail-Safe Input (FSI) protection prevents metastable conditions when the selected differential input voltage drops below 100mV.
• Unique patented input termination architecture accepts AC- or DC-coupled inputs as small as 100mV without external level shifting.
• Ultra-low jitter design guarantees less than 1ps RMS random jitter and less than 10ps peak-to-peak total jitter.

Signal Switches, Multiplexers, Decoders Applications

• Redundant clock switchover
• Fail-safe clock protection
• Enterprise servers
• Test and measurement

Signal Switches, Multiplexers, Decoders Procurement Notes

Verify that the component is sourced from authorized Microchip distributors to ensure authenticity. Confirm the specific ordering suffix matches the required packaging format, such as tube or tape and reel. Check for RoHS compliance status and lead finish specifications before finalizing procurement orders.

Signal Switches, Multiplexers, Decoders Selection Notes

Select this component for applications requiring redundant clock switching with guaranteed glitch-free transitions. Ensure the system power supply supports either 2.5V or 3.3V operation. Verify that the input signal amplitude meets the minimum requirements for the RPE and FSI functions to operate correctly within the specified industrial temperature range.

Signal Switches, Multiplexers, Decoders Part Context

The SY89845U belongs to Micrel’s Precision Edge product line, designed for high-speed digital systems. It integrates multiplexing, fanout buffering, and specialized pulse elimination logic into a single low-jitter solution. The device is optimized for environments where clock integrity during source switchover is critical.

Signal Switches, Multiplexers, Decoders Replacement Considerations

SY89843U: Precision LVPECL Runt Pulse Eliminator 2:1 MUX with 1:2 Fanout Buffer and Internal Termination. SY89844U: Precision LVDS Runt Pulse Eliminator 2:1 MUX with 1:2 Fanout and Internal Termination.

Signal Switches, Multiplexers, Decoders FAQ

How does the Fail-Safe Input function protect against metastability?

If the selected input pair drops below the minimum amplitude requirement of 100mV single-ended or 200mV differential, the output latches to the last valid clock state, eliminating oscillations and undetermined states.

What is the purpose of the CAP pin?

The CAP pin controls the Power-On Reset (POR) initialization capacitor. Connecting it to VCC disables the RPE function, while connecting it to a capacitor ensures the internal RPE logic starts in a known state.