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Details, datasheet, quote on part number:P2027A-08ST
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Datasheet text preview:
PRELIMINARY Specification
Alliance Semiconductor®
P2027A
General Purpose EMI Reduction IC
FEATURES · · · · · · · FCC approved method of EMI attenuation Provides up to 20 dB of EMI suppression Generates a low EMI spread spectrum clock of the input frequency Optimized for 27 MHz operation Internal loop filter minimizes external components and board space 3 selectable spread ranges and 2 modulation rate options SSON control pin for spread spectrum enable and disable options · · · · · · · Low cycle-to-cycle jitter 3.3V operating voltage 16 mA output drives TTL or CMOS compatible outputs Low power CMOS design Supports digital camera and other digital video and imaging applications Available in 8 pin SOIC and TSSOP
PRODUCT DESCRIPTION The P2027 is a versatile spread spectrum frequency modulator designed specifically for digital camera and other digital video and imaging applications. The P2027 reduces electromagnetic interference (EMI) at the clock source, which provides system wide reduction of EMI of all clock dependent signals. The P2027 allows significant system cost savings by reducing the number of circuit board layers and shielding that are traditionally required to pass EMI regulations. The P2027 uses the most efficient and optimized modulation profile approved by the FCC and is implemented in a proprietary all-digital method. The P2027 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". APPLICATIONS The P2027 is targeted towards DSC market as well as other imaging and digital video applications like DVD and VCD players. Figure 1 P2027 Pin Diagram
XIN/ CLK XOUT MRA VSS
1 2 3 4
8 7 6 5
VDD SR0 ModOUT SSON
May, 2002 Revision E
PulseCore A Division of Alliance Semiconductor 3160 De La Cruz Blvd., Suite 200 · Santa Clara · CA · 95054 Tel (408) 748-6988 · Fax (408) 748-0009 http://www.pulsecore.com 1 of 1
PRELIMINARY Specification
Alliance Semiconductor® Figure 2 P2027 Block Diagram
MRA SR0 SSON VDD
P2027A
Modulation XIN XOUT Feedback Divider Crystal Oscillator Frequency Divider
PLL
Phase Detector
Loop Filter
VCO
Output Divider
ModOUT
P2027 Block Diagram VSS
Table 1 - Modulation and Spreading Selection MRA 0 0 1 1 PIN DESCRIPTION PIN # 1 2 3 4 5 6 7 8 Name XIN/CLK XOUT MRA VSS SSON ModOUT SR0 VDD Type I I I P I O I P Description Connect to crystal or clock. Crystal output Digital logic input used to select Modulation Rate (see Table 1). This pin has an internal pull-up resistor. Ground Connection. Connect to system ground. Digital logic input used to enable Spread Spectrum function (Active Low). Spread Spectrum function enable when low. This pin has an internal pulllow resistor. Spread Spectrum Clock Output. Digital logic input used to select Spreading Range (see Table 1). This pin has an internal pull-up resistor. Connect to +3.3V SR0 0 1 0 1 Spreading Range Reserve +/- 0.30% +/- 0.20% +/- 0.60% Modulation rate Reserve (Fin/10)*34.72 KHz (Fin/10)*20.83 KHz (Fin/10)*20.83 KHz
May, 2002 Revision E
PulseCore A Division of Alliance Semiconductor 3160 De La Cruz Blvd., Suite 200 · Santa Clara · CA · 95054 Tel (408) 748-6988 · Fax (408) 748-0009 http://www.pulsecore.com 2 of 2
PRELIMINARY Specification
Alliance Semiconductor® SPREAD SPECTRUM SELECTION Table 1 illustrates the possible spread spectrum options. The optimal setting should minimize system EMI to the fullest without affecting system performance. The spreading is described as a percentage deviation of the center frequency (Note: the center frequency is the frequency of the external reference input on CLKIN, Pin 1). Example: P2027 is designed for DSC and digital video and imaging markets and is optimized for 27 MHz under minimum deviation settings. Selecting P2027's spread options to MRA=1 and SR0=1 for a 27 MHz input signal provides a percentage deviation of +/-0.60% (see Table 1) from the reference signal. This results in frequency on ModOUT being swept from 27.16 MHz to 26.84 MHz at a modulation rate of 56.24 KHz (see Table 1). This particular example (see Figure 3) given here is a new EMI reduction method for DSC applications and is already gaining popularity among leading manufacturers. Figure 3 - P2027 Application Schematic for Digital Still Camera
P2027A
27 MHZ crystal
1 2 3 4
CLKIN XOUT MRA VSS
P2027
VDD SR0 ModOUT SSON
8 7 6 5
Connected to CLK input pin of the system 0.1uF +3.3V
May, 2002 Revision E
PulseCore A Division of Alliance Semiconductor 3160 De La Cruz Blvd., Suite 200 · Santa Clara · CA · 95054 Tel (408) 748-6988 · Fax (408) 748-0009 http://www.pulsecore.com 3 of 3
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