DATASHEET
16 OUTPUT LOW SKEW CLOCK GENERATOR MK74CG117B
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 1
MK74CG117B REV D 073108
Description
The MK74CG117B is a monolithic CMOS high speed,
low-skew clock driver that includes an on-chip PLL. Ideal for
communications and other systems that require a large
number of high-speed clocks, the unique combination of
PLL and 16 low-skew outputs can eliminate oscillators and
low skew buffers from systems.
The device has a number of built in multipliers, making it
possible to run from one inexpensive, low frequency crystal,
and produce high frequency clock outputs. Another
selection allows the chip to run as a divider, dividing the
input clock by two (or 4 using the mode select).
The device also has a buffered reference output, allowing
multiple devices to be easily driven from one clock source.
Features
•48-pin SSOP (300 mil) package
•On-chip PLL generates output clocks up to 100 MHz from
a simple crystal or clock input
•16 low-skew outputs
•Output skew less than 250 ps on rising edges
•Ability to configure as
–16 clocks at full frequency
–12 at full and 4 at half frequency
–8 at full and 8 at half frequency
•Tri-state mode for Output Enable function
•3.3 V ±5% supply voltage
•Industrial temperature version available
Block Diagram
Clock
Synthesis
and Mode
Select
Circuitry
S2:0
M1:0
REF
3
GND
VDD
Crystal
Ocsillator
X1/ICLK
X2
The crystal requires external capacitors for
accurate tuning of the clock
2
9
Crystal or
clock input
10
Clock 16
Clock 2
Clock 1
MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 2
MK74CG117B REV D 073108
Pin Assignment
VDD
X1/ICLK
X2
CLK16
NC
VDD
VDD
S01
2
3
4
48
47
46
45
48-pin (300 mil) SSOP
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
CLK15
CLK14
GND
NC
44
43
42
41
M1
CLK13
CLK12
GND
40
39
38
37
VDD
M0
CLK11
VDD
36
35
34
33
CLK9
VDD
NC
CLK10
32
31
30
29
NC
GND
GND
S2
REF
S1
GND
GND
CLK1
CLK2
VDD
VDD
CLK3
CLK4
GND
GND
21
22
23
24
NC
CLK5
CLK6
VDD
GND
CLK8
CLK7
GND
28
27
26
25
MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 3
MK74CG117B REV D 073108
Pin Descriptions
External Components
The MK74CG117B requires a minimum number of external
components for proper operation.
Decoupling Capacitor
A decoupling capacitor of 0.1µF must be connected
between each VDD and GND. Connect the capacitor as
close to these pins as possible. For optimum device
performance, mount the decoupling capacitor on the
component side of the PCB. Avoid the use of vias in the
decoupling circuit.
PCB Layout Recommendations
For optimum device performance and lowest output phase
noise, observe the following guidelines:
1) Mount the 0.01µF decoupling capacitor on the
component side of the board as close to the VDD pin as
possible. No vias should be used between the decoupling
capacitor and VDD pin. The PCB trace to the VDD pin and
the PCB trace to the ground via should be kept as short as
possible.
2) To minimize EMI, place the 33Ω series-termination
resistor (if needed) close to the clock output.
3) An optimum layout is one with all components on the
same side of the board, thus minimizing vias through other
signal layers. Other signal traces should be routed away
from the MK74CG117B device. This includes signal traces
located underneath the device, or on layers adjacent to the
ground plane layer used by the device.
Crystal Information
The crystal used should be a fundamental mode (do not use
third overtone), parallel resonant crystal. The oscillator has
internal caps that provide the proper load for a crystal with
CL = 18 pF. The value of these capacitors is given by the
following equation:
Crystal caps (pF) = (CL - 18) x 2
Pin
Number
Pin
Name
Pin Type Pin Description
1, 15, 16, 24, 30, 35, 36, 45, 46 VDD Power Connect to VDD.
2 X1/ICLK XI Connect to a crystal input or clock.
3 X2 XO Connect to a crystal, or leave unconnected for clock
input.
4, 5, 21, 29, 44 NC — No connect. Nothing is connected to these pins.
6, 7, 11, 12, 19, 20, 27, 28, 40, 41 GND Power Connect to ground.
8, 10, 48 S2, S1, S0 Input Multiplier select pins. See table 2.
9 REF Output Crystal oscillator buffered reference clock output.
13, 14, 17, 18 CLK1 - 4 Output Clock 1 - 4. Can be either full or half speed per Table
1.
22, 23, 25, 26, 31, 32, 33, 37 CLK5 - 12 Output Clock outputs 5 - 12. At full (1x) speed unless
tristated per Table 1.
34, 39 M0, M1 Input Mode Select pins. Selects tri-state or speed of
outputs per Table 1.
38, 42, 43, 47 CLK13 - 16 Output Clock 13 - 16. Can be either full or half speed per
Table 1.
MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 4
MK74CG117B REV D 073108
Power Dissipation, Termination, and Operating
Frequency
As with all clock drivers, the power dissipated by the
MK74CG117B is affected by the external loading on the
output pins. This consists of the capacitance of the load that
is being driven, as well as the PC board trace itself. Since
this capacitance must be charged and discharged with each
cycle of the output clock, as the frequency goes up. so does
the power required. Operating below the specified
maximum output clock frequency shown in Table 2 will keep
the MK74CG117B power dissipation within acceptable
limits.
External series termination resistors must be used in series
with each output. These resistors serve two purposes: The
first is to match the source impedance to the line (PC board
trace) that is being driven. This will minimize reflections that
cause non-linear transitions on the output clock waveform.
The output impedance of the MK74CG117B is
approximately 20Ω; assuming a 50Ω line, then a 33Ω
resistor should be used at each output as shown in Figure 1.
Table 1. Tri-state and Mode Select
Table 2. Multiplier Selections (Input and CLK
Frequencies in MHz)
Figure 1. External Termination
As speeds rise, the limiting factor in device operation
becomes the power generated by having a large number of
drivers in one package. Using the external termination
resistors reduces the power dissipated within the device,
allowing output frequencies up to 100 MHz.
Note that the maximum operating frequency of the
MK74CG117A is determined by the Mode selected from
Table 1 and the Multiplier selected from Table 2. For output
frequencies above 83.3 MHz, all 16 outputs must be at the
same frequency (M1=M0=1).
When operating with a combination of 1X and 0.5X outputs,
the output frequency cannot exceed 83.3 MHz.
M1 M0 Mode at
CLK(1x)
at
CLK/2(0.5x)
Max
Output
Freq.
00 All outputs,
including
REF,
tri-stated
ZZ
0112 @ 1x,
4 @ 0.5x
CLK1–12 CLK13–16 83.3 MHz
0.8
108 @ 1x,
8 @ 0.5x
CLK5–12 CLK1–4,
13–16
83.3 MHz
1.25
11 16 outputs
@ 1x
CLK1–16 None 100 MHz
S2 S1 S0 Input Multiplier CLK Out Comments
00 0 33–50 0.5 16.5–25 Divider
only; no
PLL
00 1 20–50 1 20–50 PLL
01 0 16–40 1.25 20–50 PLL
01 1 10–50 2 20–100 PLL
10 0 8–40 2.5 20–100 PLL
10 1 8–30 3.333 26.7–100 PLL
11 0 8–25 4 32–100 PLL
11 1 8–20 5 40–90 PLL
33 ohm
To load
MK74CG117
Output
MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 5
MK74CG117B REV D 073108
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the MK74CG117B. 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.
Recommended Operation Conditions
DC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±10%, Ambient Temperature -40 to +85°C
Item Rating
Supply Voltage, VDD (referenced to GND) 7 V
All Inputs and Outputs (referenced to GND) 0.5 V to VDD+0.5 V
Ambient Operating Temperature -40 to +85°C
Storage Temperature -65 to +150°C
Junction Temperature 125°C
Soldering Temperature 260°C
Parameter Min. Typ. Max. Units
Ambient Operating Temperature -40 +85 °C
Power Supply Voltage (measured in respect to GND) +3.0 3.63 V
Parameter Symbol Conditions Min. Typ. Max. Units
Operating Voltage VDD 3.14 3.3 3.47 V
Supply Current (at 50
MHz)
IDD No load 63 mA
Input High Voltage,
ICLK
VIH pin 2 VDD-1 VDD/2 V
Input Low Voltage,
ICLK
VIL pin 2 VDD/2 1 V
Output High Voltage VOH IOH = -8 mA VDD-0.4 V
Output High Voltage VOH IOH = -12 mA 2.0 V
Output Low Voltage,
3.3 V
VOL IOL = 12 mA 0.4 V
Short Circuit Current Each output ±35 mA
Input Capacitance CIN S0, S1, FRSEL pins 7 6 pF
MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 6
MK74CG117B REV D 073108
AC Electrical Characteristics
Unless stated otherwise, VDD = 3.3 V ±10%, Ambient Temperature 0 to +85° C, CL = 15 pF
Note 1: Based upon characterization data with a 33 Ω series termination resistor and 15 pF capacitor to ground.
Note 2: Between any two outputs with equal loading.
Note 3: Additional load may be driven with the addition of an external heat sink. Contact IDT for details.
Thermal Characteristics for 48-pin SSOP
Parameter Symbol Conditions Min. Typ. Max. Units
Input Clock Frequency See table 2
Input Crystal Frequency Except when S2=S1=1 8 20 MHz
Output Clock Frequency (see
tables 1, 2)
M1=M0=1 100 MHz
Output Clock Duty Cycle At VDD/2 45 50 55 %
Output Clock Rising Edge Skew VDD=3.3 V, Note 2 150 250 ps
Absolute Clock Period Jitter,
except REF
VDD=3.3 V ±300 ps
Absolute Clock Period Jitter, REF VDD=3.3 V ±500 ps
Output Clock Rise Time tR0.8 to 2.0 V, Note 1 1.5 2 ns
Output Clock Fall Time tF2.0 V to 0.8 V, Note 1 1.5 2 ns
Maximum Load per Total of 16
Outputs, with 33 Ω termination,
Note 3
100 MHz output clock 240 pF
83.3 MHz output clock 320 pF
Parameter Symbol Conditions Min. Typ. Max. Units
Thermal Resistance Junction to Ambient θJA Still air 80 °C/W
θJA 1 m/s air flow 67 °C/W
θJA 3 m/s air flow 54 °C/W
Thermal Resistance Junction to Case θJC 45 °C/W
MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
IDT™
16 OUTPUT LOW SKEW CLOCK GENERATOR 7
MK74CG117B REV D 073108
Package Outline and Package Dimensions (48-pin SSOP, 300 Mil. Body)
Package dimensions are kept current with JEDEC Publication No. 95
Ordering Information
While the information presented herein has been checked for both accuracy and reliability, Integrated Device Technology, Inc. (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.
Part / Order Number Marking Shipping Packaging Package Temperature
MK74CG117BF MK74CG117BF Tubes 48-pin SSOP 0 to +70°C
MK74CG117BFT MK74CG117BF Tape and Reel 48-pin SSOP 0 to +70°C
MK74CG117BFLF 74CG117BFLF Tubes 48-pin SSOP 0 to +70°C
MK74CG117BFLFT 74CG117BFLF Tape and Reel 48-pin SSOP 0 to +70°C
MK74CG117BFI MK74CG117BFI Tubes 48-pin SSOP -40 to +85°C
MK74CG117BFIT MK74CG117BFI Tape and Reel 48-pin SSOP -40 to +85°C
MK74CG117BFILF 74CG117BFILF Tubes 48-pin SSOP -40 to +85°C
MK74CG117BFILFT 74CG117BFILF Tape and Reel 48-pin SSOP -40 to +85°C
INDEX
AREA
1 2
48
D
E1 E
SEATING
PLANE
A1
A
A2
e
- C -
b
aaa C
c
L
Millimeters Inches
Symbol Min Max Min Max
A 2.412.80.095.110
A1 0.20 0.40 .008 .016
b 0.20 0.34 .008 .0135
c 0.130.25.005.010
D 15.75 16.00 .620 .630
E 10.03 10.68 .395 .420
E1 7.40 7.60 .291 .299
e 0.635 BASIC 0.025 BASIC
h 0.380.64.015.025
L 0.501.02.020.040
α0°8°0°8°
© 2006 Integrated Device Technology, Inc. All rights reserved. Product specifications subject to change without notice. IDT and the IDT logo are trademarks of Integrated Device
Technology, Inc. Accelerated Thinking is a service mark of Integrated Device Technology, Inc. All other brands, product names and marks are or may be trademarks or registered
trademarks used to identify products or services of their respective owners.
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Integrated Device Technology, Inc.
www.idt.com
For Sales
800-345-7015
408-284-8200
Fax: 408-284-2775
For Tech Support
www.idt.com/go/clockhelp
Innovate with IDT and accelerate your future networks. Contact:
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MK74CG117B
16 OUTPUT LOW SKEW CLOCK GENERATOR CLOCK SYNTHESIZER
