ICST ICS307M-01I Serially programmable clock source Datasheet

ICS307-01/02
SERIALLY PROGRAMMABLE CLOCK SOURCE
Description
Features
The ICS307-01 and ICS307-02 are versatile serially
programmable clock sources which take up very little
board space. They can generate any frequency from 6
to 200 MHz and have a second configurable output.
The outputs can be reprogrammed on the fly and will
lock to a new frequency in 10 ms or less. Smooth
transitions (in which the clock duty cycle remains near
50%) are guaranteed if the output divider is not
changed.
• Packaged in 16-pin (150 mil wide) SOIC
• ICS307M-02 and -02I available in Pb (lead) free
The devices includes a PDTS pin which tri-states the
output clocks and powers down the entire chip.
The ICS307-02 features a default clock output at
start-up and is recommended for all new designs.
This product is intended for clock generation. It has low
output jitter (variation in the output period), but input to
output skew and jitter are not defined nor guaranteed.
For applications which require defined input to output
skew, use the ICS527-01.
package
• Highly accurate frequency generation
• Serially programmable: user determines the output
frequency via a 3 wire interface
•
•
•
•
•
•
•
•
Eliminates need for custom quartz
Input crystal frequency of 5 - 27 MHz
Output clock frequencies up to 200 MHz
Power down tri-state mode
Very low jitter
Operating voltage of 3.3 V or 5 V
25 mA drive capability at TTL levels
Industrial temperature version available
Block Diagram
VDD
TTL
SCLK
DATA
Shift
Register
STROBE
2
C1:C0
3
S2:S0
2
F1:F0
VCO
Divider
7
R6:R7
X1/ICLK
Crystal or
clock input
V8:V0
9
Crystal
Oscillator
X2
Reference
Divider
CLK1
Phase Comparator,
Charge Pump, and
Loop Filter
Output
Divider
VCO
PDTS
Function
Select
3
S2:S0
Optional crystal capacitors
CLK2
3
F1:F0
GND
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SERIALLY PROGRAMMABLE CLOCK SOURCE
Pin Assignment
X1/ICLK
1
16
X2
NC
2
15
NC
VDD
3
14
NC
NC
4
13
PDTS
GND
5
12
DATA
CLK2
6
11
CLK1
NC
7
10
SCLK
8
9
NC
STRO BE
16 pin (150 m il) SO IC
Pin Descriptions
Pin
Number
Pin
Name
Pin
Type
1
X1/ICLK
XI
2
NC
-
3
VDD
Power
4
NC
-
5
GND
Power
Connect to ground.
6
CLK2
Output
Output clock 2, determined by F0 - F1. Can be reference, REF/2, CLK1/2 , or off.
7
NC
-
8
SCLK
Input
Serial clock. See timing diagram.
9
STROBE
Input
Strobe to load data. See timing diagram.
10
NC
-
11
CLK1
Output
12
DATA
Input
Data input. Serial input for three words which set the output clock(s).
13
PDTS
Input
Powers down entire chip, tri states CLK1 and CLK2 outputs when low. Internal
pull-up.
14
NC
-
No connect. Do not connect anything to this pin.
15
NC
-
No connect. Do not connect anything to this pin.
16
X2
XO
Crystal connection (REF frequency). Connect to a parallel resonant crystal or an
input clock.
No connect. Do not connect anything to this pin.
Connect to 3.3 V or 5 V.
No connect. Do not connect anything to this pin.
No connect. Do not connect anything to this pin.
No connect. Do not connect anything to this pin.
Output clock 1, determined by R0 - R6, V0 - V8, S0 - S2, and input frequency.
Input crystal connection. Connect to a crystal or leave unconnected for clock
input.
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SERIALLY PROGRAMMABLE CLOCK SOURCE
Determining the Output Frequency
On power-up, the ICS307-01 on-chip registers can
have random values so almost any frequency may be
output from the part. CLK1 will always have some clock
signal present, but CLK2 could possibly be OFF (low).
The ICS307-02 on-chip registers are initially configured
to provide a x1 output clock on both the CLK1 and
CLK2 outputs. The output frequency will be the same
as the input clock or crystal. This is useful if the ICS307
will provide the initial system clock at power-up. Since
this feature is an advantage in most systems, the
ICS307-02 is recommended for new designs.
To determine the best combination of VCO, reference,
and output dividers, see the online calculator at
http://www.icst.com/products/ics307inputForm.html or
contact ICS by sending an e-mail to [email protected]
with the desired input crystal or clock and the desired
output frequency.
With programming, the user has full control in changing
the desired output frequency to any value over the
range shown in Table 1 on page 4. The output of the
ICS307 can be determined by the following equation:
VDW + 8
CLK1Frequency = InputFrequency ⋅ 2 ⋅ ------------------------------------------( RDW + 2 ) ⋅ OD
Where:
VCO Divider Word (VDW) = 4 to 511 (0, 1, 2, 3
are not permitted)
Reference Divider Word (RDW) = 1 to 127 (0 is
not permitted)
Output Divider = values on page 4
The following operating ranges should be observed.
For the commercial temperature range:
VDW + 8
55MHz < InputFrequency ⋅ 2 ⋅ ------------------------ < 400MHz
RDW + 2
InputFrequency
200kHz < ---------------------------------------------RDW + 2
And for the industrial temperature range:
VDW + 8
60MHz < InputFrequency ⋅ 2 ⋅ ------------------------ < 360MHz
RDW + 2
Input Frequency
200kHz < ------------------------------------------RDW + 2
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Setting the Device Characteristics
The tables below show the settings which can be configured, as well as the VCO and Reference dividers.
Table 1. Output Divide and Maximum Output Frequency
S2
S1
S0
CLK1 Output
Divide
Max. Frequency
5 V or 3.3 V (MHz)
Max. Frequency
Industrial Temp. Version
0
0
0
10
40
36
0
0
1
2
200
180
0
1
0
8
50
45
0
1
1
4
100
90
1
0
0
5
80
72
1
0
1
7
55
50
1
1
0
3
135
120
1
1
1
6
67
60
Table 2. CLK2 Output
F1
F0
CLK2
0
0
REF
0
1
FREF/2
1
0
OFF (Low)
1
1
FCLK1/2
Table 3. Output Duty Cycle Configuration
TTL
Duty Cycle Measured At
Recommended VDD
0
1.4 V
5V
1
VDD/2
3.3 V
Note: The TTL bit optimizes the duty cycle at different VDD. When VDD is 5 V, set to 0 for a near-50% duty
cycle with TTL levels. When VDD is 3.3 V, set this bit to 1 so the 50% duty cycle is achieved at VDD/2.
Table 4. Crystal Load Capacitance
C1
C0
VDD = 5V
VDD = 3.3V
0
0
22.3 - 0.083 f
22.1 - 0.094 f
0
1
23.1 - 0.093 f
22.9 - 0.108 f
1
0
23.7 - 0.106 f
23.5 - 0.120 f
1
1
24.4 - 0.120 f
24.2 - 0.135 f
Note: f is the crystal frequency in MHz between 10 and 27 MHz. Effective load capacitance will be higher
for crystal frequencies lower than 10 MHz. If a clock input is used, set C1 = 0 and C0 = 0.
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SERIALLY PROGRAMMABLE CLOCK SOURCE
Bypass Mode
If R6:0 is programmed to 0000000, the PLL is powered down and bypassed; the reference frequency will
come from both CLK1 and CLK2. It is possible to generate glitches going into and out of this mode.
Configuring the ICS307
The ICS307 can be programmed to set the output functions and frequencies. The three data bytes are
written in DATA pin in this order:
C1
C0
F1
TTL
F0
S2
S1
MSB
S0
V8
LSB
MSB
V7
V6
V5
V4
V3
V2
V1
V0
LSB
MSB
R6
R5
R4
R3
R2
R1
C1 is loaded into the port first and R0 last.
R6:R0 Reference Divder Word (RDW)
V8:V0 VCO Divider Word (VDW)
S2:S0 Output Divider Select (OD)
F1:F0 Function of CLK2 Output
TTL
Duty Cycle Settings
C1:C0 Internal Load Capacitance for Crystal
The ICS307 can be reprogrammed at any time during operation. If R6:0, V8:0, TTL, or C1:0 are changed, the
frequency will transition smoothly to the new value over about 1 ms, without glitches or short cycles. If S2:0 is
changed, it is possible to generate glitches on CLK1 and also on CLK2 for F1:0 = 1 1.
Changing F1:0 will generate glitches on CLK2.
Power up default values for ICS307-02
0
0
1
0
0
0
1
1
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
0
The input frequency will come from both outputs.
A warning about using the default configuration with input frequencies lower than 13.75 MHz
The VCO will run only as low as its minimum frequency, which is guaranteed to be no more than 55 MHz.
So, in the powerup default condition, the PLL is guaranteed to lock to the input frequency down to 55/4 =
13.75 MHz. However, the part will typically run much slower. The typical minimum VCO frequency is about
30 - 40 MHz, depending on voltage, temperature, and lot variation; so in the powerup default setting, the
CLK2 output will be a minimum of 7.5 - 10 MHz even if the input frequency is lower than that. The output is
not locked to the reference input and so the frequency is not very stable and the phase noise is higher. In
this condition, the CLK2 output will accurately provide the reference frequency down to 0 Hz because this
signal path bypasses the PLL.
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SERIALLY PROGRAMMABLE CLOCK SOURCE
Programming Example
To generate 66.66 MHz from a 14.31818 MHz input, the RDW should be 59, the VDW should be 276, and
the Output Divide is 2. Selecting the minimum internal load capacitance, CMOS duty cycle, and CLK2 to be
OFF means that the following three bytes are sent to the ICS307:
00110001
10001010
00111011
Byte 1
Byte 2
Byte 3
As show in Figure 2, after these 24 bits are clocked into the ICS307, taking STROBE high will send this
data to the internal latch and the CLK output will lock within 10 ms.
Note: If STROBE is in the high state and SCLK is pulsed, DATA is clocked directly to the internal latch and
the output conditions will change accordingly. Although this will not damage the ICS307, it is recommended
that STROBE be kept low while DATA is being clocked into the ICS307 in order to avoid unintended
changes on the output clocks.
AC Parameters for Writing to the ICS307
Parameter
Condition
Min.
tSETUP
Setup time
10
ns
tHOLD
Hold time after SCLK
10
ns
tW
Data wait time
10
ns
tS
Strobe pulse width
40
ns
SCLK Frequency
DATA
C1
C0
tsetup
TTL
F1
R1
Max.
Units
50
MHz
R0
thold
SCLK
tw
ts
STROBE
Figure 2. Timing Diagram for Programming the ICS307
External Components/Crystal Selection
The ICS307 requires a 0.01µF decoupling capacitor to be connected between VDD and GND. It must be connected
close to the ICS307 to minimize lead inductance. A 33Ω terminating resistor can be used in series with CLK1 and
CLK2 outputs. A parallel resonant, fundamental mode crystal with a load (correlation) capacitance of C should be
used, where C is the value calculated from Table 4. For crystals with a specified load capacitance greater than C,
additional crystal capacitors may be connected from each of the pins X1 and X2 to ground as shown in the Block
Diagram on page 1. The value (in pF) of these crystal caps should be = (CL-C)*2, where CL is the crystal load
capacitance in pF and C is the capacitance value from Table 4. These external capacitors are only required for
applications where the exact frequency is critical. For a clock input, connect to X1 and leave X2 unconnected (no
capacitors on either pin).
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SERIALLY PROGRAMMABLE CLOCK SOURCE
Absolute Maximum Ratings
Stresses above the ratings listed below can cause permanent damage to the ICS307-01/02. 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
0 to +70°C
Ambient Operating Temperature, Industrial
-40 to +85°C
Storage Temperature
-65 to +150°C
Soldering Temperature
260°C
Recommended Operation Conditions
Parameter
Min.
Max.
Units
0
+70
°C
+3.0
+5.5
V
Ambient Operating Temperature
Power Supply Voltage (measured in respect to GND)
Typ.
DC Electrical Characteristics
VDD=3.3 V ±5% , Ambient temperature 0 to +70°C, unless stated otherwise
Parameter
Symbol
Conditions
Min.
Typ.
3.0
Max.
Units
5.5
V
Operating Voltage
VDD
Input High Voltage
Input Low Voltage
Input High Voltage
VIH
VIL
VIH
X1/ICLK only
X1/ICLK only
Input Low Voltage
VIL
PDTS on ICS307-01
0.4
V
All other inputs,
ICS307-01/02
0.8
V
(VDD/2)+1 VDD/2
VDD/2 (VDD/2)-1
2
V
V
V
Output High Voltage
VOH
IOH = -25 mA
Output Low Voltage
VOL
IOL = 25 mA
Output High Voltage,
CMOS level
VOH
IOH = -4 mA
Operating Supply Current
IDD
20 MHz crystal
No load, 100 MHz out
26
mA
100 MHz out, 3.3 V
13
mA
V
0.4
VDD-0.4
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V
V
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SERIALLY PROGRAMMABLE CLOCK SOURCE
Parameter
Symbol
Short Circuit Current
Conditions
Min.
Typ.
CLK outputs
Input Capacitance
CIN
On-Chip Pull-up Resistor
RPU
Pin 13
Max.
Units
±70
mA
4
pF
270
kΩ
AC Electrical Characteristics
VDD = 3.3 V ±5%, Ambient Temperature 0 to +70° C, unless stated otherwise
Parameter
Input Frequency
Symbol
FIN
Conditions
Min.
Typ.
Max.
Units
Fundamental
crystal
5
27
MHz
Clock
2
6
50
200
MHz
MHz
I-temp version
6
180
MHz
Output Frequency (see Table 1)
Output Clock Rise Time
tOR
0.8 to 2.0 V, Note 1
1
ns
Output Clock Fall Time
tOF
2.0 to 8.0 V, Note 1
1
ns
Output Clock Duty Cycle
Power-up Time
even output divides
45
odd output divides
40
3
STROBE goes high
until CLK out
One Sigma Clock Period Jitter
Maximum Absolute Jitter
tja
49-51
Deviation from mean
55
%
60
%
10
ms
50
ps
±120
ps
Note 1: Measured with 15 pF load.
Thermal Characteristics
Parameter
Thermal Resistance Junction to
Ambient
Thermal Resistance Junction to Case
Conditions
Min.
Typ.
Max. Units
θJA
Still air
120
°C/W
θJA
1 m/s air flow
115
°C/W
θJA
3 m/s air flow
105
°C/W
58
°C/W
θJC
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SERIALLY PROGRAMMABLE CLOCK SOURCE
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
A
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°
h x 45
A1
C
-Ce
SEATING
PLANE
B
L
.10 (.004)
C
Ordering Information
Part / Order Number
ICS307M-01
ICS307M-01T
ICS307M-01I
ICS307M-01IT
ICS307M-02
ICS307M-02T
ICS307M-02LF
ICS307M-02LFT
ICS307M-02I
ICS307M-02IT
ICS307M-02ILF
ICS307M-02ILFT
Marking
ICS307M-01
ICS307M-01
ICS307M-01I
ICS307M-01I
ICS307M-02
ICS307M-02
ICS307M-02LF
ICS307M-02LF
ICS307M-02I
ICS307M-02I
ICS307M02ILF
ICS307M02ILF
Shipping packaging
Tubes
Tape and Reel
Tubes
Tape and Reel
Tubes
Tape and Reel
Tubes
Tape and Reel
Tubes
Tape and Reel
Tubes
Tape and Reel
Package
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
16-pin SOIC
Temperature
0 to +70° C
0 to +70° 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
-40 to +85° C
-40 to +85° C
-40 to +85° C
-40 to +85° C
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.
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