© Semiconductor Components Industries, LLC, 2005
November, 2005 Rev. 2
1 Publication Order Number:
NB2308A/D
NB2308A
3.3 V Zero Delay
Clock Buffer
The NB2308A is a versatile, 3.3 V zero delay buffer designed to
distribute highspeed clocks. It is available in a 16 pin package. The
part has an onchip 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 inputtooutput
propagation delay is guaranteed to be less than 250 ps, and the
outputtooutput skew is guaranteed to be less than 200 ps.
The NB2308A 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
threestated. The select input also allows the input clock to be directly
applied to the outputs for chip and system testing purposes.
Multiple NB2308A 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 NB2308A is available in five different configurations (Refer to
NB2308A Configurations Table). The NB2308Ax1* is the base part,
where the output frequencies equal the reference if there is no counter
in the feedback path. The NB2308Ax1H is the highdrive version of
the 1 and the rise and fall times on this device are much faster.
The NB2308Ax2 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 NB2308Ax3
allows the user to obtain 4X and 2X frequencies on the outputs.
The NB2308Ax4 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 NB2308Ax5H is a highdrive version with REF/2 on both
banks.
Features
Zero Input Output Propagation Delay, Adjustable by Capacitive
Load on FBK Input
Multiple Configurations Refer to NB2308A Configurations Table
Input Frequency Range: 15 MHz to 133 MHz
Multiple LowSkew Outputs
OutputOutput Skew Less than 200 ps
DeviceDevice Skew Less than 700 ps
Two banks of four outputs, threestateable by two select inputs
Less than 200 ps CycletoCycle Jitter
Available in 16pin SOIC and TSSOP Packages
3.3V operation
Advanced 0.35 CMOS Technology
PbFree Packages are Available**
*x = C for Commercial; I for Industrial.
**For additional information on our PbFree strategy and soldering details,
please download the ON Semiconductor Soldering and Mounting Techniques
Reference Manual, SOLDERRM/D.
MARKING
DIAGRAMS*
XXXX = Device Code
A = Assembly Location
WL, L = Wafer Lot
Y = Year
WW, W = Work Week
G or G = PbFree Package
(Note: Microdot may be in either location)
*For additional marking information, refer to
Application Note AND8002/D.
See detailed ordering and shipping information in the package
dimensions section on page 9 of this data sheet.
ORDERING INFORMATION
http://onsemi.com
SOIC16
D SUFFIX
CASE 751B
1
16
1
16
1
16
1
16
XXXX
XXXX
ALYWG
G
XXXXXXXXXG
AWLYWW
TSSOP16
DT SUFFIX
CASE 948F
NB2308A
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2
FBK
CLKA1
CLKA2
CLKA3
CLKA4
PLL
MUX
CLKB1
CLKB2
CLKB3
CLKB4
SELECT INPUT
DECODING
Figure 1. Block Diagram
(see Figures 11, 12, 13, 14 and 15 for device specific Block Diagrams)
REF
S2
S1
Extra Divider (2, 3)
Extra Divider (5H)
Extra Divider (3, 4)
B2
B2
B2
Table 1. CONFIGURATIONS (x = C for Commercial; I for Industrial)
Device Feedback From Bank A Frequency Bank B Frequency
NB2308Ax1 Bank A or Bank B Reference Reference
NB2308Ax1H Bank A or Bank B Reference Reference
NB2308Ax2 Bank A Reference Reference B2
NB2308Ax2 Bank B 2 X Reference Reference
NB2308Ax3 Bank A 2 X Reference Reference or Reference (Note 1)
NB2308Ax3 Bank B 4 X Reference 2 X Reference
NB2308Ax4 Bank A or Bank B 2 X Reference 2 X Reference
NB2308Ax5H Bank A or Bank B Reference B2 Reference B2
1. Output phase is indeterminant (0° or 180° from input clock). If phase integrity is required, use the NB2308Ax2.
Table 2. SELECT INPUT DECODING
S2 S1 Clock A1 A4 Clock B1 B4 Output Source PLL ShutDown
0 0 Threestate Threestate PLL Y
0 1 Driven Threestate PLL N
1 0 Driven (Note 2) Driven Reference Y
1 1 Driven Driven PLL N
2. Outputs inverted on 23082 and 23083 in bypass mode, S2 = 1 and S1 = 0.
NB2308A
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3
Figure 2. Pin Configuration
V
DD
1
2
3
4
16
15
14
13
REF
CLKA1
CLKA2
GND
FBK
CLKA4
CLKA3
NB2308A
V
DD
5
6
7
8
12
11
10
9
CLKB1
CLKB2
S2
CLKB4
CLKB3
S1
GND
Table 3. PIN DESCRIPTION
Pin # Pin Name Description
1 REF (Note 3) Input reference frequency, 5 V tolerant input.
2 CLKA1 (Note 4) Buffered clock output, Bank A.
3 CLKA2 (Note 4) Buffered clock output, Bank A.
4 V
DD
3.3 V supply.
5 GND Ground.
6 CLKB1 (Note 4) Buffered clock output, Bank B.
7 CLKB2 (Note 4) Buffered clock output, Bank B.
8 S2 (Note 5) Select input, bit 2.
9 S1 (Note 5) Select input, bit 1.
10 CLKB3 (Note 4) Buffered clock output, Bank B.
11 CLKB4 (Note 4) Buffered clock output, Bank B.
12 GND Ground.
13 V
DD
3.3 V supply.
14 CLKA3 (Note 4) Buffered clock output, Bank A.
15 CLKA4 (Note 4) Buffered clock output, Bank A.
16 FBK PLL feedback input.
3. Weak pulldown.
4. Weak pulldown on all outputs.
5. Weak pullup on these inputs.

NB2308AC1HDR2G

Mfr. #:
Manufacturer:
ON Semiconductor
Description:
Phase Locked Loops - PLL 3.3V Eight Output Zero Delay Buffer
Lifecycle:
New from this manufacturer.
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