B9940L
2.5V or 3.3V, 200-MHz, 1:18 Clock Distribution Buffer
Features
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•
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200-MHz clock support
LVPECL or LVCMOS/LVTTL clock input
LVCMOS/LVTTL compatible inputs
18 clock outputs: drive up to 36 clock lines
150-ps max. output-to-output skew
Dual- or single-supply operation:
— 3.3V core and 3.3V outputs
— 3.3V core and 2.5V outputs
— 2.5V core and 2.5V outputs
• Pin-compatible with MPC940L
• Industrial temperature range: -40°C to 85°C
• 32-pin LQFP package
Description
The B9940L is a low-voltage clock distribution buffer with the
capability to select either a differential LVPECL- or an
LVCMOS/LVTTL-compatible input clock. The two clock
sources can be used to provide for a test clock as well as the
primary system clock. All other control inputs are
LVCMOS/LVTTL compatible. The eighteen outputs are 2.5V or
3.3V compatible and can drive two series-terminated 50Ω
transmission lines. With this capability the B9940L has an
effective fan-out of 1:36. Low output-to-output skews make the
B9940L an ideal clock distribution buffer for nested clock trees
in the most demanding of synchronous systems.
Block Diagram
Pin Configuration
VDDC
32
31
30
29
28
27
26
25
VSS
Q0
Q1
Q2
Q3
Q4
Q5
VDD
PECL_CLK
PECL_CLK#
TCLK
TCLK_SEL
0
1
VDDC
18
Q0-Q17
VSS
VSS
TCLK
T C LK _S E L
P E C L _C L K
P E C L_ C LK #
VDD
VDDC
1
2
3
4
5
6
7
8
9
B9940L
10
11
12
13
14
15
16
24
23
22
21
20
19
18
17
Q6
Q7
Q8
VDD
Q9
Q 10
Q 11
VSS
Q17
Q16
Q15
Q14
Q13
VSS
Q12
Cypress Semiconductor Corporation
Document #: 38-07105 Rev. *C
•
3901 North First Street
•
San Jose
,
CA 95134
•
408-943-2600
Revised December 26, 2002
VDDC
CYPRESS [ CYPRESS SEMICONDUCTOR ]
