ASM3P2856A/B generate the required four custom clock
frequencies
for
the
LCD
Projector.
An
inexpensive
14.7456MHz crystal is used to generate a 14.7456MHz
used by the microcomputer, a 27MHz used by Video, a
non-spread 65MHz, and a centre spread 65MHz clock used
by the LCD projector system. The spread spectrum clock
(± 20 ppm)
has +/- 0.5% or +/- 1% spread options.
The spread
spectrum clock of ASM3P2856A/B reduces electromagnetic
interference (EMI) at the clock source. This allows
significant system cost savings by reducing the number of
circuit board layers and shielding that are required to pass
EMI regulations.
Custom Clock Generator for LCD Projector
Generates EMI optimized clock signals for
LCD Projector system
Uses an inexpensive 14.7456 MHz crystal for
generating the required Outputs
Frequency outputs:
•
CLK1 : 27.002MHz
•
CLK2 : 14.7456MHz (Zero ppm)
•
CLK3 : 65MHz (±
15
ppm)
•
CLK4,CLK5 : 65MHz (±15 ppm) Spread
Spectrum Clock
•
ASM3P2856A: +/- 1% centre spread
ASM3P2856B: selectable +/-1.0% & +/-1.5%
Centre Spread option
•
•
•
Applications
ASM3P2856A/B is targeted for use in LCD Projectors.
Supply voltage range 3.3V ± 0.3V.
Available in 16 Pin TSSOP
Available in Commercial Temperature range
Block Diagram
V
DD
SSON SS%
CLK1
XIN
XOUT
CLK2
Crystal
Oscillator
PLL
CLK3
CLK4
CLK5
GND
PulseCore Semiconductor Corporation
1715 S. Bascom Ave Suite 200 Campbell, CA 95008
•
Tel: 408-879-9077
•
Fax: 408-879-9018
www.pulsecoresemi.com
Notice: The information in this document is subject to change without notice.
November 2006
rev 0.1
Pin Configuration
XIN
XOUT
V
DD
V
DD
GND
GND
CLK1
CLK2
1
2
3
4
5
6
7
8
16
15
14
13
ASM3P2856A
ASM3P2856B
V
DD
NC
GND
SSON
SS%
CLK5
CLK4
CLK3
V
DD
NC
GND
NC
NC
CLK5
CLK4
CLK3
XIN
XOUT
V
DD
V
DD
GND
GND
CLK1
CLK2
1
2
3
4
5
6
7
8
16
15
14
13
ASM3P2856A
ASM3P2856B
12
11
10
9
12
11
10
9
Pin Description
Pin#
1
2
3
4
5
6
7
8
9
10
11
12
Pin Name
XIN
XOUT
V
DD
V
DD
GND
GND
CLK1
CLK2
CLK3
CLK4
CLK5
NC
SS%
NC
Type
I
O
P
P
P
P
O
O
O
O
O
-
I
-
I
P
-
P
Description
Connection to crystal or external reference frequency input. This pin has dual
functions. It can be connected either to an external crystal or an external
reference clock.
Connection to crystal. If using an external reference clock, this pin must be left
unconnected.
Power supply for the entire Chip
Power supply for the entire Chip
Ground to entire chip
Ground to entire chip
27.002 MHz Clock output. Refer to Input & Output Frequency Table for details.
Reference Clock Output. Refer to Input & Output Frequency Table for details.
65 MHz non-spread Clock output. Refer to Input & Output Frequency Table for
details.
65 MHz Spread Spectrum Clock Output. Refer to Input & Output Frequency
Table for details.
65 MHz Spread Spectrum Clock Output. Refer to Input & Output Frequency
Table for details.
No Connection for ASM3P2856A
Spread percentage selection pin for ASM3P2856B. Refer to Spread Selection
Table for details. Has an internal pull down resistor
No Connection for ASM3P2856A
Spread spectrum selection. When SSON is HIGH, spread spectrum is enabled
and when LOW, it turns off the spread spectrum. Connect the pin to ground
When Spread Spectrum feature is not required. Has an internal pull up resistor.
Ground to entire chip
No Connection
Power supply for the entire Chip
13
14
15
16
SSON
GND
NC
V
DD
Custom Clock generator for LCD Project
Notice: The information in this document is subject to change without notice.
2 of 8
November 2006
rev 0.1
Input & Output Clock Frequency Table
Input
Frequency
CLK1
CLK2
CLK3
14.7456 MHz
CLK4
65 MHz Spread Spectrum Clock
(+/-0.5 or +/- 1%)
CLK5
65 MHz Spread Spectrum Clock
(+/-0.5 or +/-1%)
ASM3P2856A
ASM3P2856B
Output Frequencies
Frequency Accuracy of
synthesized clocks
±20
ppm
Zero ppm
±15
ppm
±15
ppm
27.002 MHz
14.7456 MHz
65 MHz Non- Spread clock
±15
ppm
Spread Selection Table
SS%
0
1
Spread Percentage
± 1.0%
± 1.5%
Typical Application Schematic for LCD Projector
+ 3.3V
14.7456 MHz
fundamental
Crystal
+ 3.3V
1
2
3
XIN
XOUT
V
DD
V
DD
NC
16
15
GND
14
SSON
13
0.1uF
4
V
DD
5
6
Make SSON Pin
HIGH to enable
Spread Spectrum
SS% Pin selects
different Spread
deviations
65MHz SS Clock
65MHz SS Clock
65MHz Clock
ASM3P2856B
GND
GND
CLK1
SS%
CLK5
CLK4
CLK3
12
11
10
9
27.002MHz Clock
14.7456MHz Clock
7
8
CLK2
Custom Clock generator for LCD Project
Notice: The information in this document is subject to change without notice.
3 of 8
November 2006
rev 0.1
Absolute Maximum Ratings
Symbol
VDD
V
IN
T
STG
T
A
T
s
T
J
T
DV
ASM3P2856A
ASM3P2856B
Parameter
Power Supply Voltage relative to GND
Input Voltage relative to GND (Input Pins)
Storage temperature
Operating temperature
Max. Soldering Temperature (10 sec)
Junction Temperature
Static Discharge Voltage
(As per JEDEC STD22- A114-B)
Rating
-0.5 to +4.6
-0.5 to VDD+0.5
-65 to +125
0 to 70
260
150
2
Unit
V
°C
°C
°C
°C
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.
DC Electrical Characteristics
(Test condition: All parameters are measured at room temperature (+ 25°C) unless otherwise stated)
Symbol
V
IL
V
IH
I
IL
I
IH
I
XOL
I
XOH
V
OL
V
OH
I
DD
I
CC
VDD
t
ON
Z
OUT
* XIN is pulled low
Parameter
Input low voltage
Input high voltage
Input low current
Input high current
XOUT output low current (V
XOL
@0.4V, VDD=3.3V)
XOUT output high current (V
XOH
@2.5V, VDD=3.3V)
Output low voltage (VDD = 3.3V, I
OL
= 10mA)
Output high voltage (VDD = 3.3V, I
OH
= 10mA)
Static supply current*
Dynamic supply current ( VDD =3.3V)
Operating Voltage
Power-up time (first locked cycle after power-up)
Output impedance
Min
GND - 0.3
2.0
-
-
-
-
-
2.5
-
-
3.0
-
-
Typ
-
-
-
-
3
3
-
-
TBD
TBD
3.3
-
TBD
Max
0.8
VDD + 0.3
-35
35
-
-
0.4
-
-
-
3.6
5
-
Unit
V
V
µA
µA
mA
mA
V
V
µA
mA
V
mS
Ω
Custom Clock generator for LCD Project
Notice: The information in this document is subject to change without notice.
4 of 8
November 2006
rev 0.1
AC Electrical Characteristics
Symbol
XIN
Input frequency
CLK1
CLK2
F
OUT
Output frequency
CLK3
CLK4 (SS Clock )
CLK5 (SS Clock )
f
d
t
LH
*
t
HL
*
t
JC
t
D
Frequency Deviation
(CLK4, CLK5 )
For SS% = 0
For SS% = 1
-
-
-
40
-
ASM3P2856A
ASM3P2856B
Parameter
Min
-
-
-
-
Typ
14.7456
27.002
14.7456
65
65
65
±
1.0
±
1.5
1.4
1.2
TBD
50
Max
-
-
-
-
Unit
MHz
MHz
-
-
-
-
60
%
nS
nS
pS
%
Output rise time (measured from 0.8 to 2.0V)
Output fall time (measured at 2.0V to 0.8V)
Jitter (Cycle to cycle)
Output duty cycle
* t
LH
and t
HL
are measured into a capacitive load of 15pF
Custom Clock generator for LCD Project
Notice: The information in this document is subject to change without notice.
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