HTML datasheet archive (search documentation on electronic components) Search datasheet (1.687.043 components)
Search field

Datasheet: I2560B-08SR (Alliance Semiconductor Corporation)

Low Frequency EMI Reduction

 

Download: PDF   ZIP
Alliance Semiconductor Corporation
November 2003
P2560B

rev 1.0
Alliance Semiconductor
2575, Augustine Drive
Santa Clara, CA
Tel: 408.855.4900
Fax: 408.855.4999
www.alsc.com
Notice: The information in this document is subject to change without notice.

Features
FCC approved method of EMI attenuation
Generates a low EMI spread spectrum and a non-
spread reference signal of the input clock
frequency
Optimized for input frequency range from 20 to 32
MHz
Internal loop filter minimizes external components
and board space
Two selectable spread ranges
Low inherent cycle-to-cycle jitter
3.3 V or 5 V operating voltage
CMOS/TTL compatible inputs and outputs
Ultra low power CMOS design: 5.50 mA @3.3 V
Supports notebook VGA and other LCD timing
controller applications
SSON pin for Spread Spectrum On/Off and
Standby Mode controls
Available in 8-pin SOIC and TSSOP
Product Description
The P2560B is a versatile spread spectrum frequency
modulator designed specifically for a wide range of clock
frequencies. It reduces electromagnetic interference
(EMI) at the clock source allowing system-wide reduction
of EMI of downstream clock and data dependent signals.
It allows significant system cost savings by reducing the
number of circuit board layers and shielding traditionally
required to pass EMI regulations.

The P2560B modulates the output of a single PLL in
order to spread the bandwidth of a synthesized clock,
thereby decreasing 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 clock generators. Lowering EMI by increasing
a signal's bandwidth is called spread spectrum clock
generation.

The P2560B uses the most efficient and optimized
modulation profile approved by the FCC and is
implemented by using a proprietary all-digital method.
Applications
The P2560B is targeted toward the notebook VGA chip
and other displays using an LVDS interface, PC
peripheral devices, and embedded systems


Block Diagram
November 2003
P2560B

rev 1.0
Low Frequency EMI Reduction
2 of 7
Notice: The information in this document is subject to change without notice.
Pin Configuration
Standby Mode Selection
CLKIN
SSON/SBM
Spread Spectrum
ModOUT
PLL
Mode
Disabled 0
N/A
Disabled
Disabled Standby
Disabled 1
N/A
Disabled
Free
running
Free running
Enabled 0
Off
Reference
Disabled Buffer
out
Enabled 1
On
Normal
Normal Normal

Spread Range Selection, VDD = 3.3 V
CLKIN frequency
Spreading range
Modulation rate
20 MHz
1.16%
25 MHz
1.13%
27 MHz
1.11%
30 MHz
1.0%
32 MHz
1.0%
(CLKIN/10) * 20.83 kHz

Pin Description
Pin# Pin Name Type
Description
1 XIN/CLK I
Crystal connection or external reference frequency input. This pin has dual
functions. It can be connected to either an external crystal or an external
reference clock.
2 XOUT O
Crystal connection. If using an external reference, this pin must be left
unconnected.
3 DIV2 I
Digital logic input used to select normal output mode or divide-by-2 output mode.
When this pin is HIGH, the frequency of the output clock is the same as the input
clock frequency. When it is tied LOW, the output frequency is half the input clock
frequency. This pin has an internal pull-up resistor.
4
VSS
P
Ground to entire chip.
5 SR0 I
Digital logic input used to select Spreading Range (Refer Spread Deviation
Table). This pin has an internal pull-up resistor.
6 SSON# I
Digital logic input used to enable Spread Spectrum function (Active LOW).
Spread Spectrum function enabled when LOW, disabled when HIGH. This pin
has an internal pull-low resistor.
7
MODOUT
O
Spread spectrum low EMI output.
8
VDD
P
Power supply for the entire chip (5V).
P2560B
November 2003
P2560B

rev 1.0
Low Frequency EMI Reduction
3 of 7
Notice: The information in this document is subject to change without notice.

Schematic for Notebook VGA Application
P2560B
November 2003
P2560B

rev 1.0
Low Frequency EMI Reduction
4 of 7
Notice: The information in this document is subject to change without notice.
Absolute Maximum Ratings
Symbol
Parameter
Rating
Unit
V
DD
, V
IN
Voltage on any pin with respect to GND
-0.5 to +7.0
V
T
STG
Storage temperature
-65 to +125
C
T
A
Operating temperature
0 to +70
C

DC Electrical Characteristics
Symbol
Parameter
Min
Typ
Max
Unit
V
IL
Input low voltage
GND - 0.3
0.8
V
V
IH
Input high voltage
2.0
VDD + 0.3
V
I
IL
Input low current (pull-up resistor on inputs SR0 and
SSON/SBM)
-35
A
I
IH
Input high current
35
A
at 0.4 V, V
DD
= 3.3V
3
mA
I
XOL
XOUT output low
current
at 0.4 V, V
DD
= 5.0 V
20
mA
at 2.5 V, V
DD
= 3.3 V
3
mA
I
XOH
XOUT output high
current
at 4.5 V, V
DD
= 5.0 V
20
mA
V
DD
= 3.3 V, I
OL
= 20 mA
0.4
V
V
OL
Output low voltage
V
DD
= 5.0 V, I
OL
= 20 mA
V
V
DD
= 3.3 V, I
OL
= 20 mA
2.5
V
V
OH
Output high voltage
V
DD
= 5.0 V, I
OL
= 20 mA
4.5
V
I
DD
Static supply current standby mode
0.6
mA
Normal mode:
fIN-min
fIN-typ
fIN-max
3.3 V and 10 pF loading
3.2
7.0
mA
I
CC
Dynamic supply current
5.0 V and 10 pF loading
6.2
13.6
mA
V
DD
Operating
voltage
2.7
3.3
5.5
V
t
ON
Power-up time (first locked cycle after power up)
0.18
mS
Z
OUT
Clock output impedance
50
AC Electrical Characteristics
Symbol
Parameter
Min
Typ
Max
Unit
f
IN
Input
frequency
20
32 MHz
f
OUT
Output
frequency
20
32 MHz
Measured at 0.8 V to 2.0 V
0.7
0.9
1.1
ns
t
LH
1
Output rise time
Measured at 1.2 V to 3.75 V
0.75
ns
Measured at 2.0 V to 0.8 V
0.6
0.8
1.0
ns
t
HL
1
Output fall time
Measured at 1.2 V to 3.75 V
0.75
ns
t
JC
Jitter (cycle to cycle)
360
ps
t
D
Output duty cycle
45
50
55
%
November 2003
P2560B

rev 1.0
Low Frequency EMI Reduction
5 of 7
Notice: The information in this document is subject to change without notice.

Package Information
8-Pin SOIC




INCHES
MILLIMETERS
SYMBOL
MIN
NOR
MAX
MIN
NOR
MAX
A
0.057 0.064 0.071 1.45 1.63 1.80
A1
0.004 0.007 0.010 0.10 0.18 0.25
A2
0.053 0.061 0.069 1.35 1.55 1.75
B
0.012 0.016 0.020 0.31 0.41 0.51
C
0.004 0.006 0.010 0.10 0.15 0.25
D
0.186 0.194 0.202 4.72 4.92 5.12
E
0.148 0.156 0.164 3.75 3.95 4.15
e
0.050 BSC 1.27 BSC
H
0.224 0.236 0.248 5.70 6.00 6.30
L
0.012 0.020 0.028 0.30 0.50 0.70
a
0 5 8 0 5 8
Note: Controlling dimensions are millimeters.
SOIC - 0.074 grams unit weight
8-Pin TSSOP





INCHES
MILLIMETERS
SYMBOL
MIN
NOR
MAX
MIN
NOR
MAX
A
0.047
1.10
A1
0.002 0.006
0.05 0.15
A2
0.031 0.039 0.041 0.80 1.00 1.05
B
0.007 0.012
0.19 0.30
C
0.004 0.008
0.09 0.20
D
0.114 0.118 0.122 2.90 3.00 3.10
E
0.169 0.173 0.177 4.30 4.40 4.50
e
0.026 BSC 0.65 BSC
H
0.244 0.252 0.260 6.20 6.40 6.60
L
0.018 0.024 0.030 0.45 0.60 0.75
a
0 8 0 8
Note: Controlling dimensions are millimeters.
TSSOP - 0.034 grams unit weight


P2560B
© 2017 • ICSheet
Contact form
Main page