SY89473U_10 Datasheet, PDF (10/11 Pages) Micrel Semiconductor – Precision LVPECL 2:1 Multiplexer with 1:2

Micrel, Inc.
LVPECL Output Interface Applications
LVPECL has a high input impedance, a very low
output impedance (open emitter), and a small signal
swing which results in low EMI. LVPECL is ideal for
driving 50Ω- and-100Ω-controlled impedance
transmission lines. There are several techniques for
terminating the LVPECL output including: Parallel
Termination-Thevenin
Equivalent,
Parallel
Termination (3-resistor), and AC-coupled
Termination. Unused output pairs may be left
floating. However, single-ended outputs must be
terminated, or balanced.
SY89473U
Note:
1. Power-saving alternative to Thevenin termination.
2. Place termination resistors as close to destination inputs as
possible.
3. Rb resistor sets the DC bias voltage, equal to V_T.
4. For 2.5V systems, Rb = 19Ω.
Figure 4b. Parallel Termination (3-Resistor)
Note:
1. For +2.5V systems, R1 = 250Ω, R2 = 62.5Ω.
Figure 4a. Parallel Termination-Thevenin Equivalent
Related Product and Support Information
Part Number Function
Data Sheet Link
SY89474U
Precision LVDS 2:1 Multiplexer with
1:2 Fanout and Internal Termination
www.micrel.com/product-info/products/sy89474u.shtml
SY89475U
Precision CML 2:1 Multiplexer with
1:2 Fanout and Internal Termination
www.micrel.com/product-info/products/sy89475u.shtml
HBW
Solutions
New Products and Applications
www.micrel.com/product-info/products/solutions.shtml
May 2007
10
M9999-052207-B
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