SY89845U

SY89845U Precision CML Runt Pulse Eliminator 2:1 MUX with 1:2 Fanout and Internal Termination General Description The SY89845U is a low jitter CML, 2:1 differential input multiplexer (MUX) optimized for redundant source switchover applications. Unlike standard multiplexers, the SY89845U unique 2:1 Runt Pulse Eliminator (RPE) MUX prevents any short cycles or “runt” pulses during switchover. In addition, a unique Fail-Safe Input protection prevents metastable conditions when the selected input clock fails to a DC voltage (voltage between the pins of the differential input drops below 100mV). The differential input includes Micrel’s unique, 3-pin input termination architecture that allows customers to interface to any differential signal (AC- or DCcoupled) as small as 100mV (200mVPP) without any level shifting or termination resistor networks in the signal path. The outputs are 400mV CML with fast rise/fall times guaranteed to be less than 80ps. The SY89845U operates from a 2.5V ±5% or 3.3V ±10% supply and is guaranteed over the full industrial temperature range of –40°C to +85°C. The SY89845U is part of Micrel’s high-speed, Precision Edge® product line. All support documentation can be found on Micrel’s web site at: www.micrel.com. Features Precision Edge® Selects between two sources, and provides a glitchfree, stable CML output Guaranteed AC performance over temperature and supply voltage: – Wide operating frequency: 1kHz to >1.5GHz – < 840ps In-to-Out tpd – < 80ps tr/...