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NB2579A Low Power, Reduced EMI Clock Synthesizer
The NB2579A is a versatile spread spectrum frequency modulator designed specifically for a wide range of clock frequencies. The NB2579A reduces ElectroMagnetic Interference (EMI) at the clock source, allowing system wide reduction of EMI of all clock dependent signals. The NB2579A 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 NB2579A uses the most efficient and optimized modulation profile approved by the FCC and is implemented by using a proprietary all digital method. The NB2579A 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 NB2579A is targeted towards all portable devices with very low power requirements like MP3 players and digital still cameras.
Features http://onsemi.com MARKING DIAGRAM*
6 1 TSOP−6 (TSOT−23−6) SN SUFFIX CASE 318G E01 A Y W G
E01AYWG G 1
= 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 / 2.5 V Supply Operating Current less than 4.0 mA Low Power CMOS Design Input Frequency Range: 13 MHz to 30 MHz Generates a 1X Low EMI Spread Spectrum clock of the Input Frequency Spread Spectrum Enable Control Frequency Deviation "1% @ 24 MHz 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 7 of this data sheet.
© Semiconductor Components Industries, LLC, 2006
December, 2006 − Rev. 3
1
Publication Order Number: NB2579A/D
NB2579A
SSON VDD
XIN/CLKIN XOUT Crystal Oscillator Frequency Divider Feedback Divider
Modulation
PLL
Phase Detector
Loop Filter
VCO
Output Divider ModOUT
Figure 1. Block Diagram Table 1. KEY SPECIFICATIONS
Description Supply Voltages Frequency Range Cycle−to−Cycle Jitter Output Duty Cycle Modulation Rate Equation Frequency Deviation
VSS
Specification VDD = 3.3 V / 2.5 V 13 MHz < CLKIN < 30 MHz 200 ps (maximum) 45/55% (worst case) FIN/640 "1% @ 24 MHz
SSON XOUT XIN/CLKIN
1 2 3
6
VSS ModOUT VDD
NB2579A
5 4
Figure 2. Pin Configuration Table 2. PIN DESCRIPTION
Pin # 1 2 3 4 5 6 Pin Name SSON XOUT XIN/CLKIN VDD ModOUT VSS Type I O I P O P Description When SSON is HIGH, the spread spectrum is enabled and when LOW, it turns off the spread spectrum. Connect the pin to ground when the spread spectrum feature is not required. 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. Spread spectrum clock output. Ground connection.
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NB2579A
Figure 3. Modulation Profile
Table 3. MAXIMUM RATINGS
Symbol VDD, VIN TSTG TA Ts TJ TDV Description Voltage on any pin with respect to Ground Storage Temperature Operating Temperature Max. Soldering Temperature (10 sec) Junction Temperature Static Discharge Voltage (As per MIL−STD−883, Method 3015) Rating 0.5 to +7.0 −65 to +125 0 to 70 260 150 2 Unit V °C °C °C °C kV
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.
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NB2579A
Table 4. DC ELECTRICAL CHARACTERISTICS FOR 2.5 V SUPPLY (Test Conditions: All parameters are measured at room
temperature 25°C) Symbol VIL VIH IIL IIH IXOL IXOH VOL VOH IDD ICC VDD tON ZOUT Input LOW Voltage Input HIGH Voltage Input LOW Current Input HIGH Current XOUT Output LOW Current (@ 0.5 V, VDD = 2.5 V) XOUT Output HIGH Current (@ 1.8 V, VDD = 2.5 V) Output LOW Voltage (VDD = 2.5 V, IOL = 8.0 mA) Output HIGH Voltage (VDD = 2.5 V, IOH = 8.0 mA) Static Supply Current (Note 1) Dynamic Supply Current (2.5 V, 24 MHz, and No Load) Operating Voltage Powerup Time (first locked cycle after powerup) (Note 2) Clock Output Impedance 50 2.375 1.8 1.1 3.5 2.5 2.625 5.0 3.0 3.0 0.6 Description Min GND − 0.3 2.0 Typ Max 0.8 VDD + 0.3 −35 35 Unit V V mA mA mA mA V V mA mA V mS W
NOTE: Device will meet the specifications after thermal equilibrium has been establishe.