sy56216r Micrel Semiconductor, sy56216r Datasheet - Page 7

• Manufacturer Part Number: sy56216r
• Description: Low Voltage 1.2v/1.8v/2.5v Cml Dual Channel Buffer 4.5ghz/6.4gbps With Equalization
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
Interface Applications
For Input Interface Applications see Figures 4a
through 4f. For CML Output Termination see Figures
5a through 5d
CML Output Termination with VCCO 1.2V
For VCCO of 1.2V, Figure 5a, terminate the output
with 50Ω-to-1.2V, DC coupled, not 100Ω differentially
across the outputs.
If AC-coupling is used, Figure 5d, terminate into 50Ω-
to-1.2V before the coupling capacitor and then
connect to a high value resistor to a reference voltage.
Do not AC couple with internally terminated receiver.
For example, 50Ω ANY-IN input. AC-coupling will
offset the output voltage by 200mV and this offset
voltage will be too low for proper driver operation. Any
unused output pair needs to be terminated when
VCCO is 1.2V, do not leave floating.
Timing Diagrams
September 2008
Figure 1. Propagation Delay
CML Output Termination with 1.8V/2.5V V
For VCCO of 1.8V or 2.5V, Figure 5a and Figure 5b,
terminate with either 50Ω-to-V
differentially across the outputs. AC- or DC-coupling is
fine. See Figure 5c for AC-coupling.
Input AC-Coupling
The SY56216R input can accept AC-coupling from
any driver. Bypass VT with a 0.1µF low ESR capacitor
to VCC as shown in Figures 4c and 4d. VT has an
internal high impedance resistor divider as shown in
Figure 2a, to provide a bias voltage for AC-coupling.
Input Termination
From 1.8V CML driver. Terminate with VT tied to
1.8V. Do not terminate 100 ohms differentially.
From 2.5V CML driver. Terminate with either VT tied
to 2.5V or 100 ohms differentially.
The input cannot be DC-coupled from a 1.2V CML
driver.
7
[e-mail]
CCO
or [phone]
M9999-093008-A
or
CCO
SY56216R
100Ω