sy89874u Micrel Semiconductor, sy89874u Datasheet - Page 9

• Manufacturer Part Number: sy89874u
• Description: Sy89874u 2.5ghz Any Diff. In-to-lvpecl Programmable Clock Divider/fanout Buffer With Internal Termination
• Manufacturer: Micrel Semiconductor

Note 1.
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Note 2.
Note 3.
Note 4.
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Note 2.
M9999-031208
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Micrel, Inc.
LVPECL OUTPUT TERMINATION RECOMMENDATIONS
For +2.5V systems: R1 = 250 , R2 = 62.5
Power-saving alternative to Thevenin termination.
Place termination resistors as close to destination inputs as possible.
R
C1 is an optional bypass capacitor intended to compensate for any t
Unused output (/Q) must be terminated to balance the output.
For +2.5V systems: R1 = 250 , R2 = 62.5 , R3 = 1.25k , R4 = 1.2k .
b
resistor sets the DC bias voltage, equal to V
Figure 4a. Parallel Termination–Thevenin Equivalent
+3.3V
+3.3V
Figure 4b. Three-Resistor “Y–Termination”
“source”
/Q
Q
+3.3V
+3.3V
Figure 4d. Terminating Unused I/O
R1
130
R2
82
t
V
. For +3.3V systems R
t
Z
Z
= V
O
O
= 50
= 50
CC
Z
Z = 50
Z = 50
O
—2V
= 50
R1
130
R2
82
50
+3.3V
9
50
R1
130
R2
82
r
/t
+3.3V
f
b
mismatches.
= 46 to 50 . For +2.5V systems R
R b
50
R3
1k
R1
130
R2
82
R4
1.6k
“destination”
V
(Optional)
C1
0.01 F
t
= V
V
+3.3V
t
+3.3V
= V
CC
+3.3V
—1.3V
CC
—2V
b
= 39
Precision Edge
SY89874U
®