DATASHEET
ATI LOW EMI CLOCK GENERATOR
Description
The MK1705A generates a low EMI output clock from a
clock or crystal input. The part is designed to dither the LCD
interface clock or other clocks for ATI’s flat panel graphics
controllers. The MK1705A uses IDT’s proprietary mixture of
analog and digital Phase Locked Loop (PLL) technology to
synthesize the frequency. It also uses IDT’s patented
technique to spread the frequency spectrum of the output,
thereby reducing the frequency amplitude peaks by several
dB.
The MK1705A is designed to have the output spread
centered around the input frequency. Refer to the MK1704A
for spreading down from the input frequency or the
MK1714-0x for a crystal input and the widest selection of
spread rates and multipliers.
IDT offers many other clocks for computers and computer
peripherals. Consult IDT when you need to remove crystals
and oscillators from your board.
Note: When changing input frequency, the LEE pin must be
set low for a minimum of 10µS to allow the PLL to lock to the
new frequency. Alternatively, the PD pin maybe be set low
while changing frequencies.
MK1705A
Features
•
•
•
•
8-pin SOIC package
Provides a spread spectrum output clock
Supports ATI’s flat panel controllers
Accepts a clock input, provides same frequency dithered
output
•
Good for all VGA modes from 40 to 167 MHz
•
Peak reduction by 7 dB - 14 dB typical on 3rd - 19th odd
harmonics
•
Low EMI feature can be disabled
•
Operating voltage of 3.3 V or 5 V
•
Advanced, low power CMOS process
Block Diagram
VDD
S1:0
Low EMI Enable
Power Down
2
PLL Clock
Synthesis
and Spread
Spectrum
Circuitry
Input
Buffer
CLK
Input Clock
GND
IDT™
ATI LOW EMI CLOCK GENERATOR
1
MK1705A
REV E 101308
MK1705A
ATI LOW EMI CLOCK GENERATOR
SSCG
Pin Assignment
ICLK
VDD
GND
CLK
1
2
3
4
8
7
6
5
PD
S0
S1
LEE
Output Clock Selection Table
S1
S0
pin 6 pin 7
0
0
1
1
0
1
0
1
Input/Output
Range
pin 1/pin 4
40 to 167 MHz
60 to 167 MHz
Test
40 to 100 MHz
Frequency Spread
vs. CLK
Center ±1.25%
Center ±0.5%
Test
Center ±1%
8 pin (150 mil) SOIC
Pin Descriptions
Pin
Number
1
2
3
4
5
6
7
8
Pin
Name
ICLK
VDD
GND
CLK
LEE
S1
S0
PD
Pin
Type
XI
Power
Power
Output
Input
Input
Input
Input
Connect to +3.3 V or +5 V.
Connect to ground.
Pin Description
Connect to a clock input as shown in table above.
Clock output equal to input frequency.
Low EMI enable. Turns on the spread spectrum when high. Internal pull-up.
Frequency select 1 input. Selects input/output clock range per table above.
Internal pull-up.
Frequency select 0 input. Selects input/output clock range per table above.
Internal pull-up.
Power down. Stops output low when this pin is low. Internal pull-up.
External Components
Series Termination Resistor
Clock output traces over one inch should use series
termination. To series terminate a 50Ω trace (a commonly
used trace impedance), place a 33Ω resistor in series with
the clock line, as close to the clock output pin as possible.
The nominal impedance of the clock output is 20Ω.
between VDD and GND on pins 2 and 3 as close to the chip
as possible.
PCB Layout Recommendations
For optimum device performance and lowest output phase
noise, the following guidelines should be observed.
1) The 0.01µF decoupling capacitor should be mounted on
the component side of the board as close to the VDD pin as
Decoupling Capacitor
A decoupling capacitor of 0.01µF must be connected
IDT™
ATI LOW EMI CLOCK GENERATOR
2
MK1705A
REV E 101308
MK1705A
ATI LOW EMI CLOCK GENERATOR
SSCG
possible. No vias should be used between decoupling
capacitor and VDD pin. The PCB trace to VDD pin should
be kept as short as possible, as should the PCB trace to the
ground via. Distance of the ferrite bead and bulk decoupling
from the device is less critical.
2) The external crystal should be mounted just next to the
device with short traces. The X1 and X2 traces should not
be routed next to each other with minimum spaces, instead
they should be separated and away from other traces.
3) To minimize EMI the 33Ω series termination resistor, if
needed, should be placed close to the clock output.
4) An optimum layout is one with all components on the
same side of the board, minimizing vias through other signal
layers. Other signal traces should be routed away from the
MK1705A. This includes signal traces just underneath the
device, or on layers adjacent to the ground plane layer used
by the device.
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK1705A. These ratings, which are
standard values for IDT commercially rated parts, are stress ratings only. Functional operation of the device at these
or any other conditions above those indicated in the operational sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods can affect product reliability. Electrical
parameters are guaranteed only over the recommended operating temperature range.
Item
Supply Voltage, VDD
All Inputs and Outputs
Ambient Operating Temperature
Storage Temperature
Junction Temperature
Soldering Temperature
7V
Rating
-0.5 V to VDD+0.5 V
0 to +70° C
-65 to +150° C
125° C
260° C
Recommended Operation Conditions
Parameter
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Min.
0
+3.0
Typ.
Max.
+70
+5.5
Units
°
C
V
IDT™
ATI LOW EMI CLOCK GENERATOR
3
MK1705A
REV E 101308
MK1705A
ATI LOW EMI CLOCK GENERATOR
SSCG
DC Electrical Characteristics
Unless stated otherwise, VDD = 5 V, Ambient Temperature 0 to +70° C
Parameter
Operating Voltage
Supply Current
Input High Voltage
Input Low Voltage
Output High Voltage
Output High Voltage
Output Low Voltage
Input Capacitance
Nominal Output Impedance
Internal Pull-up Resistor
Symbol
VDD
IDD
V
IH
V
IL
V
OH
V
OH
V
OL
C
IN
Z
OUT
R
PU
Conditions
No load, 3.3V
No load, 5V
Clock input
Clock input
I
OH
= -4 mA
I
OH
= -25 mA
I
OL
= 25 mA
S0 pin
LEE pin only
Min.
3.0
Typ.
20
15
Max.
5.5
Units
V
mA
mA
V
(VDD/2)+1
VDD-0.4
2.4
VDD/2
VDD/2
(VDD/2)-1
V
V
V
0.4
7
20
500
V
pF
Ω
kΩ
AC Electrical Characteristics
Unless stated otherwise, VDD = 5 V, Ambient Temperature 0 to +70° C
Parameter
Input Frequency
Input Clock Duty Cycle
Output Rise Time
Output Fall Time
Output Clock Duty Cycle
Output Clock Frequency
Variation from Mean
EMI Peak Frequency Reduction
Symbol
Conditions
Time above VDD/2
Min.
40
20
Typ.
Max. Units
167
80
1.5
1.5
MHz
%
ns
ns
%
%
dB
t
OR
t
OF
0.8 to 2.0 V, Note 1
2.0 to 0.8 V, Note 1
Time above 1.5 V
LEE high
3rd - 19th odd harmonics
40
±0.5
7
50
60
2.5
14
Note 1: Measured with 15 pF load.
Thermal Characteristics
Parameter
Thermal Resistance Junction to
Ambient
Symbol
θ
JA
θ
JA
θ
JA
θ
JC
Conditions
Still air
1 m/s air flow
3 m/s air flow
Min.
Typ.
150
140
120
40
Max. Units
°
C/W
°
C/W
°
C/W
°
C/W
Thermal Resistance Junction to Case
IDT™
ATI LOW EMI CLOCK GENERATOR
4
MK1705A
REV E 101308
MK1705A
ATI LOW EMI CLOCK GENERATOR
SSCG
Package Outline and Package Dimensions
(8-pin SOIC, 150 Mil. Body)
Package dimensions are kept current with JEDEC Publication No. 95
8
Millimeters
Symbol
Min
Max
Inches
Min
Max
E
INDEX
AREA
H
1 2
D
A
A1
B
C
D
E
e
H
h
L
α
1.35
1.75
0.10
0.25
0.33
0.51
0.19
0.25
4.80
5.00
3.80
4.00
1.27 BASIC
5.80
6.20
0.25
0.50
0.40
1.27
0
°
8
°
.0532
.0688
.0040
.0098
.013
.020
.0075
.0098
.1890
.1968
.1497
.1574
0.050 BASIC
.2284
.2440
.010
.020
.016
.050
0
°
8
°
A
A1
h x 45
C
-C-
e
B
SEATING
PLANE
L
.10 (.004)
C
Ordering Information
Part / Order Number
MK1705A
MK1705ATR
MK1705ALF
MK1705ATRLF
Marking
MK1705A
MK1705A
MK1705AL
MK1705AL
Shipping Packaging
Tubes
Tape and Reel
Tubes
Tape and Reel
Package
8-pin SOIC
8-pin SOIC
8-pin SOIC
8-pin SOIC
Temperature
0 to +70°
0 to +70°
0 to +70°
0 to +70°
C
C
C
C
Parts that are ordered with a “LF” suffix to the part number are the Pb-Free configuration and are RoHS compliant.
While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology (IDT) assumes
no responsibility for either its use or for the infringement of any patents or other rights of third parties, which would result from its use. No
other circuits, patents, or licenses are implied. This product is intended for use in normal commercial applications. Any other applications
such as those requiring extended temperature range, high reliability, or other extraordinary environmental requirements are not
recommended without additional processing by IDT. IDT reserves the right to change any circuitry or specifications without notice. IDT
does not authorize or warrant any IDT product for use in life support devices or critical medical instruments.
IDT™
ATI LOW EMI CLOCK GENERATOR
5
MK1705A
REV E 101308
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