March 2005
rev 1.3
ASM5P23S08A
3.3V ‘SpreadTrak’ Zero Delay Buffer
General Features
•
•
•
•
Zero input - output propagation delay, adjustable by
capacitive load on FBK input.
Multiple
configurations
-
Refer
“ASM5P23S08A
Configurations” Table.
Input frequency range: 15 MHz to 133 MHz
Multiple low-skew outputs.
o
Output-output skew less than 200 pS.
o
Device-device skew less than 700 pS.
o
Two banks of four outputs, three-stateable by two
select inputs.
•
•
•
•
•
•
Less than 200 pS cycle-to-cycle jitter
(-1, -1H, -2, -3, -4, -5H).
Available in 16-pin SOIC and TSSOP packages.
3.3V operation.
Advanced 0.35µ CMOS technology.
Industrial temperature available.
‘SpreadTrak’.
The
ASM5P23S08A
(Refer
is
available
in
five
different
configurations
“ASM5P23S08A
Configurations
Multiple ASM5P23S08A devices can accept the same input
clock and distribute it. In this case the skew between the
outputs of the two devices is guaranteed to be less than
700 pS.
The ASM5P23S08A has two banks of four outputs each,
which can be controlled by the select inputs as shown in
the
Select Input Decoding Table.
If all the output clocks are
not required, Bank B can be three-stated. The select input
also allows the input clock to be directly applied to the
outputs for chip and system testing purposes.
Table). The ASM5P23S08A-1 is the base part, where the
output frequencies equal the reference if there is no
counter in the feedback path. The ASM5P23S08A-1H is
the high-drive version of the -1 and the rise and fall times
on this device are faster.
Functional Description
ASM5P23S08A is a versatile, 3.3V zero-delay buffer
designed to distribute high-speed clocks. It is available in a
16-pin package. The part has an on-chip PLL, which locks
to an input clock, presented on the REF pin. The PLL
feedback is required to be driven to FBK pin, and can be
obtained from one of the outputs. The input-to-input
propagation delay is guaranteed to be less than 350pS,
and the output-to-output skew is guaranteed to be less than
250pS.
The ASM5P23S08A-2 allows the user to obtain 2X and 1X
frequencies on each output bank. The exact configuration
and output frequencies depends on which output drives the
feedback pin. The ASM5P23S08A-3 allows the user to
obtain 4X and 2X frequencies on the outputs.
The ASM5P23S08A-4 enables the user to obtain 2X clocks
on all outputs. Thus, the part is extremely versatile, and
can be used in a variety of applications.
The ASM5P23S08A-5H is a high-drive version with REF/2
on both banks
3.3V ‘SpreadTrak’ Zero Delay Buffer
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March 2005
rev 1.3
Block Diagram
/2
REF
ASM5P23S08A
FBK
PLL
MUX
ASM5P23S08A
/2
CLKA1
CLKA2
Extra Divider (-3,-4)
Extra Divider (-5H)
S2
Select Input
Decoding
S1
/2
CLKA3
CLKA4
CLKB1
CLKB2
Extra Divider (-2,-3)
CLKB3
CLKB4
Select Input Decoding for ASM5P23S08A
S2
0
0
1
1
S1
0
1
0
1
Clock A1 - A4
Three-state
Driven
Driven
1
Clock B1 - B4
Three-state
Three-state
Driven
Driven
Output Source
PLL
PLL
Reference
PLL
PLL Shut-Down
Y
N
Y
N
Driven
ASM5P23S08A Configurations
Device
ASM5P23S08A-1
ASM5P23S08A-1H
ASM5P23S08A-2
ASM5P23S08A-2
ASM5P23S08A-3
ASM5P23S08A-3
ASM5P23S08A-4
ASM5P23S08A-5H
Feedback From
Bank A or Bank B
Bank A or Bank B
Bank A
Bank B
Bank A
Bank B
Bank A or Bank B
Bank A or Bank B
Bank A Frequency
Reference
Reference
Reference
2 X Reference
2 X Reference
4 X Reference
2 X Reference
Reference /2
Bank B Frequency
Reference
Reference
Reference /2
Reference
Reference or Reference
2
2 X Reference
2 X Reference
Reference /2
Note:
1. Outputs are non-inverted on 23S08-2 and 23S08-3 in bypass mode, S2 = 1 and S1 = 0.
2. Output phase is indeterminant (0° or 180° from input clock). If phase integrity is required, use the ASM5P23S08A-2.
3.3V
‘SpreadTrak’ Zero Delay Buffer
Notice: The information in this document is subject to change without notice.
2 of 21
March 2005
rev 1.3
‘SpreadTrak’
Many systems being designed now utilize a technology
called Spread Spectrum Frequency Timing Generation.
ASM5P23S08A is designed so as not to filter off the
Spread Spectrum feature of the Reference input, assuming
it exists. When a zero delay buffer is not designed to pass
the Spread Spectrum feature through, the result is a
ASM5P23S08A
significant amount of tracking skew which may cause
problems in the systems requiring synchronization.
Zero Delay and Skew Control
All outputs should be uniformly loaded to achieve Zero
Delay between input and output.
1500
REF-Input to CLKA/LKB Delay (pS)
1000
500
0
-30
-500
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
-1000
-1500
Output Load Difference: FBK Load - CLKA/CLKB Load (pF)
To close the feedback loop of the ASM5P23S08A, the FBK
pin can be driven from any of the eight available output
pins. The output driving the FBK pin will be driving a total
load of 7 pF plus any additional load that it drives. The
relative loading of this output (with respect to the remaining
outputs) can adjust the input output delay. This is shown in
the above graph.
For applications requiring zero input-output delay, all
outputs including the one providing feedback should be
equally loaded. If input-output delay adjustments are
required, use the above graph to calculate loading
differences between the feedback output and remaining
outputs. For zero output-output skew, make sure to load
outputs equally.
3.3V ‘SpreadTrak’ Zero Delay Buffer
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March 2005
rev 1.3
Pin Configuration
REF
CLKA1
CLKA2
V
DD
GND
CLKB1
CLKB2
S2
1
2
3
4
5
6
7
8
16
15
14
FBK
CLKA4
CLKA3
V
DD
GND
CLKB4
CLKB3
S1
ASM5P23S08A
ASM5P23S08A
13
12
11
10
9
Pin Description for ASM5P23S08A
Pin #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Pin Name
REF
3
CLKA1
4
Description
Input reference frequency, 5V tolerant input
Buffered clock output, bank A
Buffered clock output, bank A
3.3V supply
Ground
Buffered clock output, bank B
Buffered clock output, bank B
Select input, bit 2
Select input, bit 1
Buffered clock output, bank B
Buffered clock output, bank B
Ground
3.3V supply
Buffered clock output, bank A
Buffered clock output, bank A
PLL feedback input
CLKA2
4
V
DD
GND
CLKB1
4
CLKB2
4
S2
5
S1
5
CLKB3
4
CLKB4
4
GND
V
DD
CLKA3
4
CLKA4
4
FBK
Notes:
3. Weak pull-down.
4. Weak pull-down on all outputs.
5. Weak pull-up on these inputs.
3.3V
‘SpreadTrak’ Zero Delay Buffer
Notice: The information in this document is subject to change without notice.
4 of 21
March 2005
rev 1.3
Absolute Maximum Ratings
Parameter
Supply Voltage to Ground Potential
DC Input Voltage (Except REF)
DC Input Voltage (REF)
Storage Temperature
Max. Soldering Temperature (10 sec)
Junction Temperature
Static Discharge Voltage
(As per JEDEC STD 22- A114-B)
Min
-0.5
-0.5
-0.5
-65
Max
+7.0
V
DD
+ 0.5
7
+150
260
150
>2000
ASM5P23S08A
Unit
V
V
V
°C
°C
°C
V
Note: These are stress ratings only and functional usage is not implied. Exposure to absolute maximum ratings for prolonged periods can
affect device reliability.
Operating Conditions for ASM5P23S08A Commercial Temperature Devices
Parameter
V
DD
T
A
C
L
C
L
C
IN
Supply Voltage
Operating Temperature (Ambient Temperature)
Load Capacitance, below 100 MHz
Load Capacitance, from 100 MHz to 133 MHz
Input Capacitance
6
Description
Min
3.0
0
Max
3.6
70
30
10
7
Unit
V
°C
pF
pF
pF
Note:
6. Applies to both Ref Clock and FBK.
3.3V
‘SpreadTrak’ Zero Delay Buffer
Notice: The information in this document is subject to change without notice.
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