NB2879A
Low Power, Reduced EMI
Clock Synthesizer
The NB2879A is a versatile spread spectrum frequency modulator
designed specifically for a wide range of clock frequencies. The
NB2879A reduces ElectroMagnetic Interference (EMI) at the clock
source, allowing system wide reduction of EMI of all clock dependent
signals. The NB2879A allows significant system cost savings by
reducing the number of circuit board layers, ferrite beads and
shielding that are traditionally required to pass EMI regulations.
The NB2879A uses the most efficient and optimized modulation
profile approved by the FCC and is implemented by using a
proprietary all digital method.
The NB2879A modulates the output of a single PLL in order to
“spread” the bandwidth of a synthesized clock, and more importantly,
decreases the peak amplitudes of its harmonics. This results in
significantly lower system EMI compared to the typical narrow band
signal produced by oscillators and most frequency generators.
Lowering EMI by increasing a signal’s bandwidth is called ‘spread
spectrum clock generation’.
The NB2879A is targeted towards all portable devices with very
low power requirements like MP3 players, Notebooks and digital still
cameras.
Features
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MARKING
DIAGRAM*
6
1
TSOP-
-6
(TSOT- -6)
-23-
SN SUFFIX
CASE 318G
E0BAYWG
G
1
E0B
A
Y
W
G
= Specific Device Code
= Assembly Location
= Year
= Work Week
= Pb--Free Package
(Note: Microdot may be in either location)
*For additional marking information, refer to
Application Note AND8002/D.
Generates an EMI Optimized Clocking Signal at the Output
Integrated Loop Filter Components
Operates with a 3.3 V
0.3
V Supply
Operating Current less than 4.0 mA
Low Power CMOS Design
Input Frequency Range: 15 MHz to 30 MHz
Generates a 1X Low EMI Spread Spectrum clock of the Input
Frequency
Frequency Deviation
1.0%
Available in TSOP--6 Package (TSOT--23--6)
Pb--Free Package is Available
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 5 of this data sheet.
Semiconductor Components Industries, LLC, 2010
November, 2010 - Rev. 3
-
1
Publication Order Number:
NB2879A/D
NB2879A
V
DD
XINCLKIN
XOUT
Crystal
Oscillator
Frequency
Divider
Feedback
Divider
REFOUT
Modulation
PLL
Phase
Detector
Loop
Filter
V
CO
Output
Divider
ModOUT
Figure 1. Block Diagram
Table 1. KEY SPECIFICATIONS
Description
Supply Voltages
Frequency Range
Cycle--to--Cycle Jitter
Output Duty Cycle
Output Rise and Fall Times
Modulation Equation
Frequency Deviation
V
DD
= 3.3 V
0.3
V
V
SS
Specification
15 MHz < CLKIN < 30 MHz
300 ps (maximum)
40 / 60% (worst case)
1.1 ns (maximum)
F
IN
/640
1%
REFOUT
XOUT
XIN/CLKIN
1
2
3
6
V
SS
ModOUT
V
DD
NB2879A
5
4
Figure 2. Pin Configuration
Table 2. PIN DESCRIPTION
Pin #
1
2
3
4
5
6
Pin Name
REFOUT
XOUT
XIN/CLKIN
V
DD
ModOUT
V
SS
Type
O
O
I
P
O
P
Buffered output of the input frequency.
Crystal connection. If using an external reference, this pin must be left unconnected.
Crystal connection or external reference frequency input. This pin has dual functions. It can be
connected either to an external crystal or an external reference clock
Power supply for the entire chip (3.3 V).
Spread spectrum clock output.
Ground connection.
Description
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2
NB2879A
Figure 3. Modulation Profile
Table 3. MAXIMUM RATINGS
Symbol
V
DD,
V
IN
T
STG
T
A
Description
Voltage on any pin with respect to Ground
Storage Temperature
Operating Temperature
Rating
0.5 to + 7.0
--65 to +125
0 to 70
Unit
V
C
C
Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the
Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect
device reliability.
Table 4. DC ELECTRICAL CHARACTERISTICS
(Test Conditions: All parameters are measured at room temperature 25C)
Symbol
V
IL
V
IH
I
IL
I
IH
I
XOL
I
XOH
V
OL
V
OH
I
DD
I
CC
V
DD
t
ON
Z
OUT
Input LOW Voltage
Input HIGH Voltage
Input LOW Current
Input HIGH Current
XOUT Output LOW Current (@ 4.0 V, V
DD
= 3.3 V)
XOUT Output HIGH Current (@ 2.5 V, V
DD
= 3.3 V)
Output LOW Voltage (V
DD
= 3.3 V, I
OL
= 20 mA)
Output HIGH Voltage (V
DD
= 3.3 V, I
OH
= 20 mA)
Static Supply Current
Dynamic Supply Current (3.3 V, 30 MHz, and 15 pF loading)
Operating Voltage
Powerup Time (first locked cycle after powerup)
Clock Output Impedance
3.0
3.3
0.18
50
2.5
10
4
3.6
3
3
0.4
Description
Min
GND -- 0.3
2.0
Typ
Max
0.8
V
DD
+ 0.3
--35
35
Unit
V
V
mA
mA
mA
mA
V
V
mA
mA
V
mS
Ω
NOTE: Device will meet the specifications after thermal equilibrium has been established when mounted in a test socket or printed circuit
board with maintained transverse airflow greater than 500 lfpm. Electrical parameters are guaranteed only over the declared
operating temperature range. Functional operation of the device exceeding these conditions is not implied. Device specification limit
values are applied individually under normal operating conditions and not valid simultaneously.
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3
NB2879A
Table 5. AC ELECTRICAL CHARACTERISTICS
Symbol
CLKIN
ModOUT
REFOUT
t
LH
(Note 1)
t
HL
(Note 1)
t
JC
t
D
Input Frequency
Output Frequency
Output Frequency
Output Rise Time (measured at 0.8 V to 2.0 V)
Output Fall Time (measured at 2.0 V to 0.8 V)
Jitter (Cycle--to--Cycle)
Output Duty Cycle
45
50
Description
Min
15
15
15
0.7
0.6
0.9
0.8
Typ
Max
30
30
30
1.1
1.0
360
55
Unit
MHz
MHz
MHz
ns
ns
ps
%
NOTE: Device will meet the specifications after thermal equilibrium has been established when mounted in a test socket or printed circuit
board with maintained transverse airflow greater than 500 lfpm. Electrical parameters are guaranteed only over the declared
operating temperature range. Functional operation of the device exceeding these conditions is not implied. Device specification limit
values are applied individually under normal operating conditions and not valid simultaneously.
1. t
LH
and t
HL
are measured at capacitive load of 15 pF.
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4
NB2879A
ORDERING INFORMATION
Device
NB2879ASNR2
NB2879ASNR2G
Marking
E0B
E0B
Temperature Range
0C -- 70C
0C -- 70C
Package
TSOP--6
(TSOT--23--6)
TSOP--6
(TSOT--23--6)
(Pb--Free)
Shipping
†
2500 Tape & Reel
2500 Tape & Reel
Availability
Now
Contact
Sales
Representative
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
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5
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