SY58021U(2005) Ver la hoja de datos (PDF) - Micrel
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SY58021U Datasheet PDF : 9 Pages
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Micrel, Inc.
Precision Edge®
SY58021U
LVPECL OUTPUT
LVPECL output have very low output impedance (open
emitter), and small signal swing which results in low EMI.
LVPECL is ideal for driving 50Ω and 100Ω controlled
+3.3V*
impedance transmission lines. There are several techniques
in terminating the LVPECL output, as shown in Figures 4
through 6.
+3.3V*
R1
ZO = 50Ω 130Ω
R1
130Ω +3.3V*
+3.3V
SY58021U
Z = 50Ω
Z = 50Ω
+3.3V
SY58021U
ZO = 50Ω
*Note. For +2.5V systems,
R1 = 250Ω, R2 = 62.5Ω
R2
82Ω
R2
82Ω VT = VCC —2V
Figure 4. Parallel Termination-Thevenin Equivalent
“source”
50Ω
50Ω
50Ω
“destination”
Rb*
VDD C1 (optional)
0.01µF
Notes:
1. Power saving alternative to Thevenin termination.
* For +2.5V, Rb = 19Ω
* For +3.3V, Rb = 46Ω to 50Ω
2. Place termination resistors as close to destination inputs as possible.
3. Rb resistor sets the DC bias voltage, equal to VT.
Figure 5. Parallel Termination (3-Resistor)
+3.3V*
+3.3V*
SY58021U
R1
ZO = 50Ω 130Ω
ZO = 50Ω
R1
130Ω +3.3V*
*Note:
For +2.5V systems,
R1 = 250Ω, R2 = 62.5Ω
R2
82Ω
R2
82Ω VT = VCC —2V
Figure 6. Terminating Unused I/O
RELATED MICREL PRODUCTS AND SUPPORT DOCUMENTATION
Part Number
SY58020U
SY58021U
SY58022U
M-0317
Function
6GHz, 1:4 CML Fanout Buffer/Translator
Internal I/O Termnations
4GHz, 1:4 LVPECL Fanout Buffer/Translator
with Internal Termination
5.5GHz, 1:4 Fanout Buffer/Translator
w/400mV LVPECL Outputs and Internal Terminations
16-MLF™ Manufacturing Guidelines
Exposed Pad Application Note
HBW Solutions
Data Sheet Link
http://www.micrel.com/product-info/products/sy58020u.shtml
http://www.micrel.com/product-info/products/sy58021u.shtml
http://www.micrel.com/product-info/products/sy58022u.shtml
www.amkor.com/products/notes_papers/MLF_AppNote_0902.pdf
http://www.micrel.com/product-info/as/solutions.shtml
M9999-062405
hbwhelp@micrel.com or (408) 955-1690
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