B9947
3.3V, 160-MHz, 1:9 Clock Distribution Buffer
Product Features
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160-MHz Clock Support
LVCMOS/LVTTL Compatible Inputs
9 Clock Outputs: Drive up to 18 Clock Lines
Synchronous Output Enable
Output Three-state Control
350-ps Maximum Output-to-Output Skew
Pin Compatible with MPC947
Industrial Temp. Range: –40°C to +85°C
32-Pin TQFP Package
Description
The B9947 is a low-voltage clock distribution buffer with the
capability to select one of two LVCMOS/LVTTL compatible
clock inputs. The two clock sources can be used to provide for
a test clock as well as the primary system clock. All other con-
trol inputs are LVCMOS/LVTTL compatible. The nine outputs
are 3.3V LVCMOS or LVTTL compatible and can drive two
series terminated 50Ω transmission lines. With this capability
the B9947 has an effective fanout of 1:18. The outputs can
also be three-stated via the three-state input TS#. Low out-
put-to-output skews make the B9947 an ideal clock distribu-
tion buffer for nested clock trees in the most demanding of
synchronous systems.
The B9947 also provides a synchronous output enable input
for enabling or disabling the output clocks. Since this input is
internally synchronized to the input clock, potential output
glitching or runt pulse generation is eliminated.
Block Diagram
Pin Configuration
VSS
VDDC
Q0
VSS
Q1
VDDC
Q2
VSS
VDD
TCLK0
TCLK1
TCLK_SEL
SYNC_OE
TS#
0
1
VDDC
9
Q0-Q8
32
31
30
29
28
27
26
25
VSS
TCLK_SEL
TCLK0
TCLK1
SYNC_OE
TS#
VDD
VSS
1
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
B9947
9
10
11
12
13
14
15
16
VSS
Q3
VDDC
Q4
VSS
Q5
VDDC
VSS
Cypress Semiconductor Corporation
Document #: 38-07078 Rev. *C
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3901 North First Street
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San Jose
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VSS
VDDC
Q8
VSS
Q7
VDDC
Q6
VSS
CA 95134 • 408-943-2600
Revised December 22, 2002
CYPRESS [ CYPRESS SEMICONDUCTOR ]
