Maxim MAX4888A manual Detailed Description, Digital Control Input SEL, Analog Signal Levels

5.0Gbps PCI Express Passive Switches

Test Circuits/Timing Diagrams (continued)

0V OR V+

50Ω

3.3V 0.1μF

V+

SEL

COM_

NC_ MAX4888A/MAX4889A

NO_

GND

VIN

VOUT

	NETWORK
	ANALYZER
50Ω	50Ω
MEAS	REF
50Ω	50Ω

OFF-ISOLATION = 20log VOUT VIN

ON-LOSS = 20log VOUT VIN

CROSSTALK = 20log VOUT VIN

MEASUREMENTS ARE STANDARDIZED AGAINST SHORTS AT IC TERMINALS.

OFF-ISOLATION IS MEASURED BETWEEN COM_ AND "OFF" NO_ OR NC_ TERMINAL ON EACH SWITCH.

ON-LOSS IS MEASURED BETWEEN COM_ AND "ON" NO_ OR NC_ TERMINAL ON EACH SWITCH.

CROSSTALK IS MEASURED BETWEEN ANY TWO PAIRS.

SIGNAL DIRECTION THROUGH SWITCH IS REVERSED; WORST VALUES ARE RECORDED.

MAX4888A/MAX4889A

Figure 3. On-Loss, Off-Isolation, and Crosstalk

	0.1μF	3.3V
		V+
	COM_		MAX4888A/MAX4889A
			SEL
CAPACITANCE			VIL OR VIH
METER	NC_ or
	NO_
		GND

Figure 4. Channel Off-/On-Capacitance

Detailed Description

The MAX4888A/MAX4889A high-speed passive switch- es route PCIe data between two possible destinations. The MAX4888A/MAX4889A are ideal for routing PCIe sig- nals to change the system configuration. For example, in a graphics application, the MAX4888A/MAX4889A create

two sets of eight lanes from a single 16-lane bus. The MAX4888A/MAX4889A feature a single digital control input (SEL) to switch signal paths.

The MAX4888A/MAX4889A are fully specified to oper- ate from a single 3.0V to 3.6V power supply and also operate down to 1.65V.

Digital Control Input (SEL)

The MAX4888A/MAX4889A provide a single digital control input (SEL) to select the signal path between the COM__ and NO__/NC__ channels. The truth tables for the MAX4888A/MAX4889A are depicted in the Functional Diagrams/Truth Table section. Drive SEL rail-to-rail to minimize power consumption.

Analog Signal Levels

The MAX4888A/MAX4889A accept standard PCIe sig- nals to a maximum of V+ - 1.2V. Signals on the COM_+ channels are routed to either the NO_+ or NC_+ chan- nels, and signals on the COM_- channels are routed to either the NO_- or NC_- channels. The MAX4888A/ MAX4889A are bidirectional switches, allowing COM__, NO__, and NC__ to be used as either inputs or outputs.

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