P2781 D

P2781/82/84
General Purpose EMI
Reduction IC
Features
• Provides up to 15dB of EMI suppression
• FCC approved method of EMI attenuation
• Generates a 1X, 2X, and 4X low EMI spread spectrum
clock of the input frequency
• Input frequency range from 3 to 78MHz
source, which provides system wide reduction of EMI of all
clock dependent signals. The P278xA allows significant
system cost savings by reducing the number of circuit
board layers and shielding that are traditionally required to
pass EMI regulations.
The P278xA uses the most efficient and optimized
modulation profile approved by the FCC. The P278xA
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 result 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.
• External loop filter for spread % adjustment
• Spreading ranges from ±0.25% to ±5.0%
• Ultra low cycle-to-cycle jitter
• Zero-cycle slip
• 3.3V operating voltage range
• Ultra-low power CMOS design
• P278xA is available in an 8 pin SOIC Package
Product Description
The P278xA is a versatile spread spectrum frequency
modulator designed specifically for digital camera and other
digital video and imaging applications. The P278xA
reduces electromagnetic interference (EMI) at the clock
Applications
The P278xA is targeted towards MFP, xDSL, fax modem,
set-top box, USB controller, DSC, and embedded systems.
Block Diagram
FS0
FS1
LF
VDD
PLL
Modulation
XIN / CLKIN
XOUT
Crystal
Oscillator
Frequency
Divider
Feedback
Divider
Phase
Detector
Output
Divider
VCO
ModOUT
VSS
©2010 SCILLC. All rights reserved.
NOVEMBER 2010 – Rev. 2.1
Publication Order Number:
P2781/82/84
P2781/82/84
Pin Configuration
XIN / CLKIN
1
XOUT
2
FS1
3
LF
4
8 VDD
7 FS0
P278xA
6 ModOUT
5
VSS
Standard pin Configuration offered in both
8 pin SOIC Packages.
Pin Description (P278xA)
Pin#
Pin Name
Type
Description
1
XIN/CLKIN
I
2
XOUT
O
3
FS1
I
4
LF
I
5
VSS
I
Ground Connection. Connect to system ground.
6
ModOUT
O
Spread Spectrum Clock Output.
7
FS0
I
Digital logic input used to select input frequency range (see the Input Frequency
Selection Table). This pin has an internal pull-up resistor.
8
VDD
P
Connect to +3.3 V
Connect to crystal or clock input. This pin has dual functions. It can be connected
either to an external crystal or an external reference clock.
Crystal connection. If using an external reference, this pin must be left
unconnected.
Digital logic input used to select input frequency range (see the Input Frequency
Selection Table). This pin has an internal pull-up resistor.
External Loop Filter for the PLL. By changing the value of the CRC circuit, the
percentage spread can be adjusted accordingly. See the Loop Filter Selection
Table for detail value.
Input Frequency Selection Table
FS1
FS0
Input (MHz)
0
0
0
Output Frequency Scaling (MHz)
Modulation Rate (KHz)
P2781A
P2782A
P2784A
3 to 9
3 to 9
6 to 18
12 to 36
Fin / 128
1
10 to 19
10 to 19
20 to 38
40 to 76
Fin / 256
1
0
20 to 38
20 to 38
40 to 76
80 to 152
Fin / 512
1
1
39 to 78
39 to 78
78 to 156
156 to 312
Fin / 1024
Rev. 2 | Page 2 of 8 | www.onsemi.com
P2781/82/84
Loop Filter Selection Table VDD 3.3V
Contact ON Semiconductor for loop values that are not listed in the table and for
Component selection values for industrial and automotive temperatures.
Input
MHz
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21-22
23-24
25-26
27-28
29-30
31-32
33-34
35-36
37-38
39-42
43-46
47-50
51-54
55-58
59-62
63-66
67-70
71-74
75-78
BW = ±0.50%1
FS1 FS0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
BW = ±0.75%1
BW = ±1.00%1
C1
(pF)
C2
(pF)
R1
(ohm)
C1
(pF)
C2
(pF)
R1
(ohm)
C1
(pF)
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
330,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
220
270
390
510
620
820
1,000
330
390
510
560
620
750
820
910
1,000
1,200
330
390
510
560
620
750
820
910
1,000
1,200
330
390
510
560
620
750
820
910
1,000
1,200
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
330,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
100,000
300
390
560
750
1,000
1,200
1,500
510
560
750
820
1,000
1,100
1,200
1,300
1,500
1,600
560
620
750
820
1,000
1,100
1,200
1,300
1,500
1,600
560
620
750
820
1,000
1,100
1,200
1,300
1,600
1,800
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
270
Note: 1. The BW value is representative of typical conditions.
Rev. 2 | Page 3 of 8 | www.onsemi.com
C2
(pF)
R1
(ohm)
100,000
390
100,000
560
100,000
750
10,000
1,000
5,600
1,200
12,000
2,200
5,600
2,200
100,000
750
100,000 866(1%)
10,000
1,000
12,000
1,200
5,600
1,200
3,900
1,200
12,000
2,200
10,000
2,200
5,600
2,200
3,300
2,200
100,000
750
100,000 866 (1%)
10,000
1,000
12,000
1,200
6,800
1,200
3,900
1,200
12,000
2,200
10,000
2,200
5,600
2,200
3,300
2,200
100,000
750
100,000 866 (1%)
10,000
1,000
12,000
1,200
6,800
1,200
3,900
1,200
12,000
2,200
8,200
2,200
5,600
2,200
3,300
2,200
BW = ±1.25%1
C1
(pF)
C2
(pF)
R1
(ohm)
560
560
560
680
330
680
270
560
560
680
470
330
330
680
390
270
270
560
560
680
470
330
330
680
390
270
270
560
560
680
470
330
330
680
390
270
270
100,000
100,000
100,000
6,800
3,300
6,800
2,700
100,000
100,000
6,800
4,700
3,300
3,300
6,800
3,900
2,700
2,700
100,000
100,000
6,800
4,700
3,300
3,300
6,800
3,900
2,700
2,700
100,000
100,000
6,800
4,700
3,300
3,300
6,800
3,900
2,700
2,700
510
680
910
1,200
1,200
2,200
2,200
910
1,100
1,200
1,200
1,200
1,500
2,200
2,200
2,200
2,700
910
1,100
1,200
1,200
1,200
1,500
2,200
2,200
2,200
2,700
910
1,100
1,200
1,200
1,200
1,500
2,200
2,200
2,200
2,700
P2781/82/84
Spread Spectrum Selection
The P278xA performs Zero Cycle Slip when set at low percentage spreading. This allows no occurrence of system timing
error. 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.)
The P2781A is designed for PC peripheral, networking, notebook PC, and LCD monitor applications. It is optimized for
operation between 3 to 78MHz range. In the following application schematic example, the P2781A spread percentage
selection is determined by the external LF value specified in the Loop Filter Selection Table. The Input Frequency Selection
Table specifies the input frequency range. The external LF allows the user to fine tune the spread percentage to optimize the
EMI reduction benefits of the spread spectrum.
+3.3V
16 MHz
1 XIN/CLKIN VDD 8
2 XOUT
3 FS1
C2
R1
C1
4 LF
0 Ohm
FS0 7
ModOUT 6
VSS 5
P278xA
2.2 K
0.1µF
Modulated 16MHz Clock
To target Chip
Note: Both logic input pins FS1 and FS0 have to be connected to either VDD or VSS. Do not leave them floating.
Rev. 2 | Page 4 of 8 | www.onsemi.com
P2781/82/84
Absolute Maximum Ratings
Symbol
VDD, VIN
TSTG
Rating
Unit
Voltage on any pin with respect to Ground
Parameter
-0.5 to +4.6
V
Storage temperature
-65 to +125
°C
Ts
Max. Soldering Temperature (10 sec)
260
°C
TJ
Junction Temperature
150
°C
TDV
Static Discharge Voltage (As per JEDEC STD22- A114-B)
2
KV
Note: These are stress ratings only and are not implied for functional use. Exposure to absolute maximum ratings for prolonged periods of time may affect
device reliability.
Operating Conditions
Parameter
VDD
Description
Min
Max
Unit
Supply Voltage
3.0
3.6
V
-40
TA
Operating Temperature (Ambient Temperature)
+85
°C
CL
Load Capacitance
15
pF
CIN
Input Capacitance
7
pF
DC Electrical Characteristics
(Test condition: All parameters are measured at room temperature (+25°C) unless otherwise stated.)
Symbol
Parameter
VIL
Input low voltage
VIH
IXOL
Input high voltage
Input low current
(internal input pull-up resistor on FS0 and FS1)
Input high current
(internal input pull-up resistor on FS0 and FS1)
XOUT output low current
IXOH
XOUT output high current
VOL
Output low voltage (VDD = 3.3V, IOL = 20mA)
VOH
Output high voltage (VDD = 3.3V, IOH = 20mA)
IDD
Static supply current
Typical dynamic supply current
(25pF scope probe loading)
Operating voltage
IIL
IIH
ICC
VDD
Rev. 2 | Page 5 of 8 | www.onsemi.com
Max
Unit
VSS – 0.3
Min
Typ
0.8
V
2.0
VDD +0.3
V
60
µA
60
µA
10
mA
10
mA
0.4
2.5
V
3
5.2 at 3MHz
3.0
V
3.3
mA
21.2 at 82MHz
mA
3.6
V
P2781/82/84
AC Electrical Characteristics
Symbol
fIN
fOUT
Parameter
Input frequency: P278xA
Output frequency:
Min
Typ
Max
3
78
P2781A
3
78
P2782A
6
156
P2784A
12
312
Unit
MHz
tLH
P278xA
Output rise time (measured at 0.8V to 2.0V,
25pF scope probe loading)
1
nS
tHL
P278xA
Output fall time (measured at 2.0V to 0.8V, 25
pF scope probe loading)
1
nS
tJC
P2781A
Jitter (cycle-to-cycle, ±6sigma, 1000 sweeps,
±0.5% spread, I/O frequency = 16MHz)
±250
pS
tD
P2781A
Output duty cycle deviation (error from 50%
duty cycle, 25pF scope probe loading)
∆F
P278xA
Frequency deviation tolerance from BW%
stated in the Loop Filter Selection Table
Rev. 2 | Page 6 of 8 | www.onsemi.com
±1 @ 3MHz
-20
0
±2 @ 82MHz
%
+20
%
P2781/82/84
Package Information
8-Pin SOIC Package
H
E
D
A2
A
θ
C
D
e
A1
L
B
Dimensions
Symbol
Inches
Millimeters
Min
Max
Min
Max
A1
0.004
0.010
0.10
0.25
A
0.053
0.069
1.35
1.75
A2
0.049
0.059
1.25
1.50
B
0.012
0.020
0.31
0.51
C
0.007
0.010
0.18
0.25
D
0.193 BSC
4.90 BSC
E
0.154 BSC
3.91 BSC
e
0.050 BSC
1.27 BSC
H
0.236 BSC
6.00 BSC
L
0.016
0.050
θ
0°
8°
Note: Controlling dimensions are millimeters.
SOIC - 0.074 grams unit weight.
Rev. 2 | Page 7 of 8 | www.onsemi.com
0.41
1.27
0°
8°
P2781/82/84
Ordering Codes
Ordering #
Top Marking
Package Type
Temperature
P2781AF-08ST
ABG
8 PIN SOIC, TUBE, Pb Free
0°C to + 70°C
P2781AF-08SR
ABG
8 PIN SOIC, TAPE AND REEL,Pb Free
0°C to +70°C
I2781AF-08ST
ABH
8 PIN SOIC, TUBE, Pb Free
I2781AG-08SR
ABJ
8 PIN SOIC, TAPE AND REEL, Green
-40°C to +85°C
-40°C to +85°C
P2782AF-08SR
ABK
8 PIN SOIC, TAPE AND REEL,Pb Free
0°C to +70°C
P2784AF-08SR
ABO
8 PIN SOIC, TAPE AND REEL,Pb Free
0°C to +70°C
A “microdot” placed at the end of last row of marking or just below the last row toward the center of package indicates Pb-free.
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without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular
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including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or
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