DATASHEET
ICS673-01
PLL BUILDING BLOCK
Description
Features
The ICS673-01 is a low cost, high-performance Phase
Locked Loop (PLL) designed for clock synthesis and
synchronization. Included on the chip are the phase
detector, charge pump, Voltage Controlled Oscillator
(VCO), and two output buffers. One output buffer is a divide
by two of the other. Through the use of external reference
and VCO dividers (the ICS674-01), the user can customize
the clock to lock to a wide variety of input frequencies.
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Packaged in 16-pin SOIC
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Output Enable tri-states outputs
The ICS673-01 also has an output enable function that puts
both outputs into a high-impedance state. The chip also has
a power-down feature which turns off the entire device.
For applications that require low jitter or jitter attenuation,
see the MK2069.
Available in RoHS compliant package
Access to VCO input and feedback paths of PLL
Output operating range up to 120 MHz (5 V)
Able to lock MHz range outputs to kHz range inputs
through the use of external dividers
Low skew output clocks
Power-down turns off chip
VCO predivide to feedback divider of 1 or 4
25 mA output drive capability at TTL levels
Advanced, low power, sub-micron CMOS process
Single supply +3.3 V (±5%) or +5 V (±10%) operating
voltage
• Industrial and commercial temperature ranges
• Forms a complete PLL, using the ICS674-01
• For better jitter performance, use the MK1575
Block Diagram
CHCP VCOIN
VDD
2
VDD
Icp
Clock Input
REFIN
FBIN
CLK1
UP
Phase/
Frequency
Detector
VCO
DOWN
1
2
4
0
MUX
2
CLK2
Icp
PD
(entire chip)
CAP
3
GND
SEL
OE (both
outputs)
External Feedback Divider
(such as the ICS674-01)
IDT™ / ICS™ PLL BUILDING BLOCK
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Pin Assignment
VCO Predivide Select Table
SEL
VCO Predivide
F B IN
1
16
R E F IN
0
4
VDD
2
15
NC
1
1
VDD
3
14
C LK1
GND
4
13
C LK2
GND
5
12
PD
GND
6
11
SEL
CHGP
7
10
OE
V C O IN
8
9
0 = connect pin directly to ground
1 = connect pin directly to VDD
CAP
1 6 p in n a rro w (1 5 0 m il) S O IC
Pin Descriptions
Pin
Number
Pin
Name
Pin
Type
1
FBIN
Input
Feedback clock input. Connect the feedback clock to this pin.
Triggered on falling edge.
2
VDD
Power
Connect to +3.3 V or +5 V and to VDD on pin 3.
3
VDD
Power
Connect to VDD on pin 2.
4
GND
Power
Connect to ground.
5
GND
Power
Connect to ground.
6
GND
Power
Connect to ground.
7
CHGP
Output
Charge pump output. Connect to VCOIN under normal operation.
8
VCOIN
Input
Input to internal VCO.
9
CAP
Input
Loop filter return.
10
OE
Input
Output enable. Active when high. Tri-states both outputs when low.
Internal weak pull-up resistor.
11
SEL
Input
Select pin for VCO predivide to feedback divider per table above.
Internal weak pull-up resistor.
12
PD
Input
Power down. Turns off entire chip when pin is low. Outputs stop low.
Internal weak pull-up resistor.
13
CLK2
Output
Clock output 2. Low skew divide by two version of CLK1.
14
CLK1
Output
Clock output 1.
15
NC
-
16
REFIN
Input
IDT™ / ICS™ PLL BUILDING BLOCK
Pin Description
No connect. Nothing is connected internally to this pin.
Reference input. Connect reference clock to this pin. Triggered on
falling edge.
2
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Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS673-01. These ratings, which are
standard values for ICS 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
Rating
Supply Voltage, VDD
7V
All Inputs and Outputs
-0.5 V to VDD+0.5 V
Ambient Operating Temperature (commercial)
0 to +70° C
Industrial Temperature
-40 to +85° C
Storage Temperature
-65 to +150° C
Soldering Temperature
260° C
Recommended Operation Conditions
Parameter
Min.
Max.
Units
0
+70
°C
-40
+85
°C
+3.13
+5.50
V
Ambient Operating Temperature (commercial)
Ambient Operating Temperature (industrial)
Power Supply Voltage (measured in respect to GND)
Typ.
DC Electrical Characteristics
VDD=3.3 V ±5% or 5.0 V ±10%, Ambient temperature -40 to +85° C, unless stated otherwise.
Parameter
Operating Voltage
Symbol
Conditions
VDD
Typ.
3.13
Logic Input High Voltage
VIH
REFIN, FBIN,
SEL
Logic Input Low Voltage
VIL
REFIN, FBIN,
SEL
LF Input Voltage Range
VI
VOH
IOH = -25 mA
Output Low Voltage
VOL
IOL = 25 mA
Output High Voltage, CMOS
level
VOH
IOH = -8 mA
Operating Supply Current
IDD
VDD = 5.0 V,
No load, 40 MHz
Short Circuit Current
IOS
Input Capacitance
CIN
Max.
Units
5.50
V
2
V
0
Output High Voltage
IDT™ / ICS™ PLL BUILDING BLOCK
Min.
0.8
V
VDD
V
2.4
V
0.4
V
VDD-0.4
15
mA
CLK
±100
mA
SEL
5
pF
3
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AC Electrical Characteristics
VDD = 3.3 V ±5%, Ambient Temperature -40 to +85° C, CLOAD at CLK = 15 pF, unless stated otherwise.
Parameter
Symbol
Conditions
Output Clock Frequency
(from pin CLK)
fCLK
Input Clock Frequency
(into pins REFIN or FBIN)
fREF
Output Rise Time
tOR
0.8 to 2.0 V
Output Fall Time
tOF
2.0 to 0.8 V
Output Clock Duty Cycle
tDC
At VDD/2
Min.
Typ.
Max. Units
SEL = 1
1
100
MHz
SEL = 0
0.25
25
MHz
Note 1
8
MHz
1.2
2
ns
0.75
1.5
ns
50
60
%
40
Jitter, Absolute peak-to-peak
tJ
250
ps
VCO Gain
KO
190
MHz/V
Charge Pump Current
Icp
2.5
µA
VDD = 5.0 V ±10%, Ambient Temperature -40 to +85° C, CLOAD at CLK = 15 pF, unless stated otherwise.
Parameter
Symbol
Conditions
Output Clock Frequency
(from pin CLK)
fCLK
Input Clock Frequency
(into pins REFIN or FBIN)
fREF
Output Rise Time
tOR
0.8 to 2.0 V
Output Fall Time
tOF
2.0 to 0.8 V
Output Clock Duty Cycle
tDC
At VDD/2
Min.
Typ.
Max. Units
SEL = 1
1
120
MHz
SEL = 0
0.25
30
MHz
Note 1
8
MHz
0.5
1
ns
0.5
1
ns
50
55
%
45
Jitter, Absolute peak-to-peak
tJ
150
ps
VCO Gain
KO
190
MHz/V
Charge Pump Current
Icp
2.4
µA
Note 1: Minimum input frequency is limited by loop filter design. 1 kHz is a practical minimum limit.
External Components
Avoiding PLL Lockup
The ICS673-01 requires a minimum number of external
components for proper operation. A decoupling capacitor of
0.01µF should be connected between VDD and GND as
close to the ICS673-01 as possible. A series termination
resistor of 33Ω may be used at the clock output.
In some applications, the ICS673-01 can “lock up” at the
maximum VCO frequency. This is usually caused by power
supply glitches or a very slow power supply ramp. This
situation also occurs if the external divider starts to fail at
high input frequencies. The usual failure mode of a divider
circuit is that the output of the divider begins to miss clock
edges. The phase detector interprets this as a too low
output frequency and increases the VCO frequency. The
Special considerations must be made in choosing loop
components CS and CP. These can be found online at
http://www.icst.com/products/telecom/loopfiltercap.htm
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feedback divider begins to miss even more clock edges and
the VCO frequency is continually increased until it is running
at its maximum frequency. Whether caused by power supply
issues or by the external divider, the loop can only recover
by powering down the circuit or asserting PD.
VDD
R1
I CS673- 01
The simplest way to avoid this problem is to use an external
divider that always operates correctly regardless of the VCO
speed. Figures 2 and 3 show that the VCO is capable of high
speeds. By using the internal divide-by-four and/or the
CLK2 output, the maximum VCO frequency can be divided
by 2, 4, or 8 and a slower counter can be used. Using the
ICS673 internal dividers in this manner does reduce the
number of frequencies that can be exactly synthesized by
forcing the total VCO divide to change in increments of 2, 4,
or 8.
PD
C3
A. Basi c Ci r cui t
VDD
If this lockup problem occurs, there are several solutions;
three of which are described below.
I CS673-01
1. If the system has a reset or power good signal, this should
be applied to the PD pin, forcing the chip to stay powered
down until the power supply voltage has stabilized. If the
dividers are implemented in an FPGA or other circuit
configured on power-up, it is critical keep the ICS673
powered down until the dividers are working properly.
R1
D1
PD
C3
B. Fast er Di scharge
Fi g 1 . Po we r o n Re s e t Ci r c u i t s
2. If no power good signal is available, a simple power-on
reset circuit can be attached to the PD pin, as shown in
Figure 1. When the power supply ramps up, this circuit holds
PD asserted (device powered down) until the capacitor
charges.
The circuit of Figure 1A is adequate in most cases, but the
discharge rate of capacitor C3 when VDD goes low is limited
by R1. As this discharge rate determines the minimum reset
time, the circuit of Figure 1B may be used when a faster
reset time is desired. The values of R1 and C3 should be
selected to ensure that PD stays below 1.0 V until the power
supply is stable.
3. A comparator circuit may be used to monitor the loop filter
voltage as shown in Figure 2. This circuit will dump the
charge off the loop filter by asserting PD if the VCO begins
to run too fast and the PLL can recover. A good choice for
the comparator is the National Semiconductor
LMC7211BIM5X. It is low power, version of the small
(SOT-23), low cost, and has high input impedance.
The trigger voltage of the comparator is set by the voltage
divider formed by R2 and R3. The voltage should be set to
a value higher than the VCO input is expected to run during
normal operation. Typically, this might be 0.5 V below VDD.
Hysteresis should be added to the circuit by connecting R4.
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Explanation of Operation
CHGP
VCOIN
CAP
The ICS673-01 is a PLL building block circuit that includes
an integrated VCO with a wide operating range. The device
uses external PLL loop filter components which through
proper configuration allow for low input clock reference
frequencies, such as a 15.7 kHz Hsync input.
PD
CP
R2
RS
CS
+
The phase/frequency detector compares the falling edges of
the clocks inputted to FBIN and REFIN. It then generates an
error signal to the charge pump, which produces a charge
proportional to this error. The external loop filter integrates
this charge, producing a voltage that then controls the
frequency of the VCO. This process continues until the
edges of FBIN are aligned with the edges of the REFIN
clock, at which point the output frequency will be locked to
the input frequency.
R3
R4
Figure 2. Using an External Comparator
to Reset the VCO
The CLK output frequency may be up to 2x the maximum
Output Clock Frequency listed in the AC Electrical
Characteristics above when the device is in an unlocked
condition. Make sure that the external divider can operate
up to this frequency.
Figure 3. Example Configuration -- Generating a 20 MHz clock from a 200 kHz reference.
+3.3 or 5 V
CP
0.01 F
RS
SEL OE PD
200 kHz
REFIN
VDD
CHGP VCOIN
CS
CAP
ICS673-01
CLK1
40 MHz
CLK2
20 MHz
FBIN
GND
200 kHz
100
Digital Divider
such as ICS674-01
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Determining the Loop Filter Values
and CS = 1.32 nF (1.2 nF is the nearest standard value).
The loop filter components consist of CS, CP, and RS.
Calculating these values is best illustrated by an example.
Using the example in Figure 1, we can synthesize 20 MHz
from a 200 kHz input.
The capacitor CP is used to damp transients from the
charge pump and should be approximately 1/20th the size
of CS, i.e.,
The phase locked loop may be approximately described by
the following equations:
C P ≅ C S ⁄ 20
Therefore, CP = 60 pF (56 pF nearest standard value).
BandwidthNBW
R ⋅ K ⋅ I
To summarize, the loop filter components are:
CS = 1.2 nf
CP = 56 pf
RS = 26 kΩ
S
O
CP
= ------------------------------2 πN
Damping factor,ζ =
R S K O ⋅ I CP ⋅ C S
------ ----------------------------------2
N
Output Clock Alignment to REFIN
When choosing either CLK1 or CLK2 to drive the feedback
divider, ICS recommends that CLK2 be used so that the
falling edges of CLK2 and REFIN, and the rising edge of
CLK1, are all synchronized. If CLK1 is used for feedback,
CLK2 may be either a rising or falling edge when compared
to REFIN. See diagrams below.
where:
KO = VCO gain (Hz/V)
Icp = Charge pump current (A)
N = Total feedback divide from VCO,
including the internal VCO post divider
CS = Loop filter capacitor (Farads)
RS = Loop filter resistor (Ohms)
CLK1
As a general rule, the bandwidth should be at least 20 times
less than the reference frequency, i.e.,
BW ≤( REFIN ) ⁄ 20
CLK2
REFIN
In this example, using the above equation, bandwidth
should be less than or equal to 10 kHz. By setting the
bandwith to 10kHz and using the first equation, RS can be
determined since all other variables are known. In the
example of Figure 1, N = 200, comprising the divide by 2 on
the chip (VCO post divider) and the external divide by 100.
Therefore, the bandwidth equation becomes:
6
CLK2 Feedback
CLK1
–
⋅ 190 ⋅ 10 ⋅ 2.5 ⋅ 10
0,000 = -----------------------------------------------------------------2π ⋅ 200
RS
CLK2
REFIN
and RS = 26 kΩ
CLK1 Feedback
Choosing a damping factor of 0.7 (a minimal damping factor
than can be used to ensure fast lock time), damping factor
equation becomes:
6
0.7
=
–6
25, 000 190 ⋅ 10 ⋅ 2.5 ⋅ 10 ⋅ C S
--------------- --------------------------------------------------------------------2
200
IDT™ / ICS™ PLL BUILDING BLOCK
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Package Outline and Package Dimensions (16-pin SOIC, 150 Mil. Narrow Body)
Package dimensions are kept current with JEDEC Publication No. 95
Millimeters
16
Symbol
E
Min
A
A1
B
C
D
E
e
H
h
L
α
H
INDEX
AREA
1 2
D
Inches*
Max
Min
1.35
1.75
0.10
0.25
0.33
0.51
0.19
0.25
9.80
10.00
3.80
4.00
1.27 BASIC
5.80
6.20
0.25
0.50
0.40
1.27
0°
8°
Max
.0532
.0688
.0040
.0098
.013
.020
.0075
.0098
.3859
.3937
.1497
.1574
0.050 BASIC
.2284
.2440
.010
.020
.016
.050
0°
8°
*For reference only. Controlling dimensions in mm.
A
h x 45
A1
C
-Ce
B
SEATING
PLANE
L
.10 (.004)
C
Ordering Information
Part / Order Number
Marking
Shipping Packaging
Package
Temperature
673M-01I
673M-01IT
673M-01ILF
673M-01ILFT
673M-01
673M-01T
673M-01LF
673M-01LFT
ICS673M-01I
ICS673M-01I
673M-01ILF
673M-01ILF
ICS673M-01
ICS673M-01
673M-01LF
673M-01LF
Tubes
Tape and Reel
Tubes
Tape and Reel
Tubes
Tape and Reel
Tubes
Tape and Reel
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
-40 to +85° C
-40 to +85° C
-40 to +85° C
-40 to +85° C
0 to +70° C
0 to +70° C
0 to +70° C
0 to +70° 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 Circuit Systems (ICS) 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 ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS
does not authorize or warrant any ICS product for use in life support devices or critical medical instruments.
IDT™ / ICS™ PLL BUILDING BLOCK
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800-345-7015
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Fax: 408-284-2775
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800 345 7015
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Integrated Device Technology
Singapore (1997) Pte. Ltd.
Reg. No. 199707558G
435 Orchard Road
#20-03 Wisma Atria
Singapore 238877
+65 6 887 5505
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Prime House
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Leatherhead, Surrey
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+44 1372 363 339
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