ICS ICS84321

ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
GENERAL DESCRIPTION
FEATURES
The ICS84321 is a general purpose, dual output
Crystal-to-3.3V Differential LVPECL High Frequency
HiPerClockS™
Synthesizer and a member of the HiPerClockS™
family of High Performance Clock Solutions from
ICS. The ICS84321 has a selectable TEST_CLK or
crystal inputs. The VCO operates at a frequency range of 620MHz
to 780MHz. The VCO frequency is programmed in steps equal
to the value of the input reference or crystal frequency. The VCO
and output frequency can be programmed using the serial or
parallel interfaces to the configuration logic.
• Dual differential 3.3V LVPECL outputs
ICS
• Selectable crystal oscillator interface
or LVCMOS/LVTTL TEST_CLK
• Output frequency range: 103.3MHz to 260MHz
• Crystal input frequency range: 14MHz to 40MHz
• VCO range: 620MHz to 780MHz
• Parallel or serial interface for programming counter
and output dividers
• RMS period jitter: 3ps (typical)
• RMS phase jitter at 155.52MHz, using a 38.88MHz crystal
(12kHz to 20MHz): 2.5ps (typical)
Phase noise: 155.52MHz
Offset
Noise Power
100Hz .................. -84.1 dBc/Hz
1kHz ................ -109.8 dBc/Hz
10kHz ................ -126.3 dBc/Hz
100kHz ................ -128.7 dBc/Hz
• 3.3V supply voltage
• 0°C to 70°C ambient operating temperature
• Lead-Free package RoHS compliant
BLOCK DIAGRAM
PIN ASSIGNMENT
XTAL_IN
nP_LOAD
M0
M1
M2
M3
M4
XTAL_SEL
TEST_CLK
VCO_SEL
VCO_SEL
0
32 31 30 29 28 27 26 25
XTAL_IN
OSC
1
XTAL_OUT
PLL
PHASE DETECTOR
MR
VCO
÷M
1
3
4
5
6
TEST_CLK
M7
3
22
XTAL_SEL
M8
4
21
VCCA
N0
5
20
S_LOAD
N1
6
19
S_DATA
nc
7
18
S_CLOCK
VEE
8
17
MR
ICS84321
9 10 11 12 13 14 15 16
VEE
nFOUT0
FOUT0
VCCO
nFOUT1
TEST
32-Lead LQFP
7mm x 7mm x 1.4mm package body
Y Package
Top View
M0:M8
N0:N1
84321AY
XTAL_OUT
23
FOUT1
CONFIGURATION
INTERFACE
LOGIC
24
2
VCC
FOUT0
nFOUT0
FOUT1
nFOUT1
1
M6
TEST
S_LOAD
S_DATA
S_CLOCK
nP_LOAD
0
÷
÷
÷
÷
M5
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1
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
FUNCTIONAL DESCRIPTION
NOTE: The functional description that follows describes operation using a 25MHz crystal. Valid PLL loop divider values
for different crystal or input frequencies are defined in the Input Frequency Characteristics, Table 5, NOTE 1.
cific default state that will automatically occur during powerup. The TEST output is LOW when operating in the parallel
input mode. The relationship between the VCO frequency, the
crystal frequency and the M divider is defined as follows:
fVCO = fxtal x M
The ICS84321 features a fully integrated PLL and therefore
requires no external components for setting the loop bandwidth. A fundamental crystal is used as the input to the onchip oscillator. The output of the oscillator is fed into the phase
detector. A 25MHz crystal provides a 25MHz phase detector
reference frequency. The VCO of the PLL operates over a
range of 620MHz to 780MHz. The output of the M divider is
also applied to the phase detector.
The M value and the required values of M0 through M8 are
shown in Table 3B, Programmable VCO Frequency Function
Table. Valid M values for which the PLL will achieve lock for a
25MHz reference are defined as 25 ≤ M ≤ 31. The frequency
out is defined as follows:
FOUT = fVCO = fxtal x M
N
N
Serial operation occurs when nP_LOAD is HIGH and S_LOAD
is LOW. The shift register is loaded by sampling the S_DATA
bits with the rising edge of S_CLOCK. The contents of the
shift register are loaded into the M divider and N output divider when S_LOAD transitions from LOW-to-HIGH. The M
divide and N output divide values are latched on the HIGH-toLOW transition of S_LOAD. If S_LOAD is held HIGH, data at
the S_DATA input is passed directly to the M divider and N
output divider on each rising edge of S_CLOCK. The serial
mode can be used to program the M and N bits and test bits
T1 and T0. The internal registers T0 and T1 determine the state
of the TEST output as follows:
T1 T0
TEST Output
The phase detector and the M divider force the VCO output frequency to be M times the reference frequency by adjusting the
VCO control voltage. Note that for some values of M (either too
high or too low), the PLL will not achieve lock. The output of the
VCO is scaled by a divider prior to being sent to each of the LVPECL
output buffers. The divider provides a 50% output duty cycle.
The programmable features of the ICS84321 support two input modes to program the M divider and N output divider. The
two input operational modes are parallel and serial. Figure 1
shows the timing diagram for each mode. In parallel mode,
the nP_LOAD input is initially LOW. The data on inputs M0
through M8 and N0 and N1 is passed directly to the M divider
and N output divider. On the LOW-to-HIGH transition of the
nP_LOAD input, the data is latched and the M divider remains
loaded until the next LOW transition on nP_LOAD or until a
serial event occurs. As a result, the M and N bits can be
hardwired to set the M divider and N output divider to a spe-
0
0
LOW
0
1
S_DATA, Shift Register Input
1
0
Output of M divider
1
1
CMOS Fout
SERIAL LOADING
S_CLOCK
S_DATA
S_LOAD
T1
t
S
T0
*NULL
N1
N0
M8
M7
M6
M5
M4
M3
M2
M1
M0
t
H
nP_LOAD
t
S
PARALLEL LOADING
M, N
M0:M8, N0:N1
nP_LOAD
t
S
t
H
S_LOAD
Time
FIGURE 1. PARALLEL & SERIAL LOAD OPERATIONS
*NOTE: The NULL timing slot must be observed.
84321AY
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2
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
TABLE 1. PIN DESCRIPTIONS
Number
Name
1
2, 3, 4,
28, 29,
30, 31, 32
M5
M6, M7, M8,
M0, M1,
M2, M3, M4
5, 6
Type
Input
Description
Pullup
Input
M divider inputs. Data latched on LOW-to-HIGH transition
Pulldown of nP_LOAD input. LVCMOS / LVTTL interface levels.
N0, N1
Input
Pulldown
7
nc
Unused
8, 16
VEE
Power
9
TEST
Output
10
VCC
Power
Negative supply pins.
Test output which is ACTIVE in the serial mode of operation.
Output driven LOW in parallel mode.
LVCMOS/LVTTL interface levels.
Core supply pin.
11, 12
FOUT1, nFOUT1
Output
Differential output for the synthesizer. LVPECL interface levels.
Determines output divider value as defined in Table 3C,
Function Table. LVCMOS / LVTTL interface levels.
No connect.
13
VCCO
Power
Output supply pin.
14, 15
FOUT0, nFOUT0
Output
17
MR
Input
Pulldown
18
S_CLOCK
Input
Pulldown
19
S_DATA
Input
Pulldown
20
S_LOAD
Input
Pulldown
21
VCCA
Power
22
XTAL_SEL
Input
Pullup
23
24,
25
TEST_CLK
XTAL_OUT,
XTAL_IN
Input
Pulldown
26
nP_LOAD
Input
Pulldown
27
VCO_SEL
Input
Pullup
Differential output for the synthesizer. LVPECL interface levels.
Active High Master Reset. When logic HIGH, the internal dividers
are reset causing the true outputs FOUTx to go low, and the inver ted
outputs nFOUTx to go high. When logic LOW, the internal dividers
and the outputs are enabled. Asser tion of MR does not affect loaded
M, N, and T values. LVCMOS / LVTTL interface levels.
Clocks in serial data present at S_DATA input into the shift register
on the rising edge of S_CLOCK. LVCMOS / LVTTL interface levels.
Shift register serial input. Data sampled on the rising edge of
S_CLOCK. LVCMOS/LVTTL interface levels.
Controls transition of data from shift register into the dividers.
LVCMOS / LVTTL interface levels.
Analog supply pin.
Selects between cr ystal or test inputs as the PLL reference source.
Selects XTAL inputs when HIGH. Selects TEST_CLK when LOW.
LVCMOS / LVTTL interface levels.
Test clock input. LVCMOS / LVTTL interface levels.
Crystal oscillator interface. XTAL_IN is the input.
XTAL_OUT is the output.
Parallel load input. Determines when data present at M8:M0 is
loaded into M divider, and when data present at N1:N0 sets the
N output divider value. LVCMOS / LVTTL interface levels.
Determines whether synthesizer is in PLL or bypass mode.
LVCMOS / LVTTL interface levels.
Input
NOTE: Pullup and Pulldown refer to internal input resistors. See Table 2, Pin Characteristics, for typical values.
TABLE 2. PIN CHARACTERISTICS
Symbol
Parameter
Test Conditions
Minimum
Typical
Maximum
Units
CIN
Input Capacitance
4
pF
RPULLUP
Input Pullup Resistor
51
kΩ
RPULLDOWN
Input Pulldown Resistor
51
kΩ
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3
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
TABLE 3A. PARALLEL
AND
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
SERIAL MODE FUNCTION TABLE
Inputs
Conditions
MR
nP_LOAD
M
N
S_LOAD
S_CLOCK
S_DATA
H
X
X
X
X
X
X
Reset. Forces outputs LOW.
L
L
Data
Data
X
X
X
Data on M and N inputs passed directly to the M
divider and N output divider. TEST output forced LOW.
L
↑
Data
Data
L
X
X
L
H
X
X
L
↑
Data
L
H
X
X
↑
L
Data
L
H
X
X
↓
L
Data
M divider and N output divider values are latched.
L
H
X
X
L
X
X
Parallel or serial input do not affect shift registers.
L
H
X
X
H
↑
Data
Data is latched into input registers and remains loaded
until next LOW transition or until a serial event occurs.
Serial input mode. Shift register is loaded with data on
S_DATA on each rising edge of S_CLOCK.
Contents of the shift register are passed to the
M divider and N output divider.
S_DATA passed directly to M divider as it is clocked.
NOTE: L = LOW
H = HIGH
X = Don't care
↑ = Rising edge transition
↓ = Falling edge transition
TABLE 3B. PROGRAMMABLE VCO FREQUENCY FUNCTION TABLE
VCO Frequency
(MHz)
M Divide
625
25
256
128
64
32
16
8
4
2
1
M8
M7
M6
M5
M4
M3
M2
M1
M0
0
0
0
0
1
1
0
0
1
650
26
0
0
0
0
1
1
0
1
0
675
27
0
0
0
0
1
1
0
1
1
•
•
•
•
•
•
•
•
•
•
•
775
31
0
0
0
0
1
1
1
1
NOTE 1: These M divide values and the resulting frequencies correspond to crystal or TEST_CLK input frequency
of 25MHz.
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1
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
TABLE 3C. PROGRAMMABLE OUTPUT DIVIDER FUNCTION TABLE
Inputs
N Divider Value
Output Frequency (MHz)
N1
N0
Minimum
Maximum
0
0
3
206.7
260
0
1
4
155
195
1
0
5
124
156
1
1
6
103.3
130
TABLE 3D. COMMONLY USED CONFIGURATION FUNCTION TABLE
Input
Crystal (MHz)
M Divider Value
N Divider Value
Output Frequency (MHz)
19.44
32
4
155.52
19.53125
32
4
156.25
25
25
4
156.25
25
25
5
125
25.50
25
3
212.50
25.50
25
4
159.375
25.50
25
6
106.25
38.88
16
4
155.52
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REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC
4.6V
Inputs, VI
-0.5V to VCC + 0.5 V
Outputs, IO
Continuous Current
Surge Current
50mA
100mA
Package Thermal Impedance, θJA
47.9°C/W (0 lfpm)
Storage Temperature, TSTG
-65°C to 150°C
NOTE: Stresses beyond those listed under Absolute
Maximum Ratings may cause permanent damage to the
device. These ratings are stress specifications only. Functional
operation of product at these conditions or any conditions beyond those listed in the DC Characteristics or AC Characteristics is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect product reliability.
TABLE 4A. POWER SUPPLY DC CHARACTERISTICS, VCC = VCCA = VCCO = 3.3V±5%, TA = 0°C TO 70°C
Symbol
Parameter
Test Conditions
VCC
Core Supply Voltage
Minimum
Typical
Maximum
Units
3.135
3.3
3.465
V
VCCA
Analog Supply Voltage
3.135
3.3
3.465
V
VCCO
Output Supply Voltage
3.135
3.3
3.465
V
IEE
Power Supply Current
178
mA
ICCA
Analog Supply Current
26
mA
Maximum
Units
2
VCC + 0.3
V
2
VCC + 0.3
V
-0.3
0.8
V
-0.3
1.3
V
VCC = VIN = 3.465V
150
µA
VCC = VIN = 3.465V
5
µA
TABLE 4B. LVCMOS / LVTTL DC CHARACTERISTICS, VCC = VCCA = VCCO = 3.3V±5%, TA = 0°C TO 70°C
Symbol
VIH
VIL
IIH
Parameter
Input
High Voltage
Input
Low Voltage
Input
High Current
Test Conditions
VCO_SEL, XTAL_SEL, MR,
S_LOAD, nP_LOAD, N0:N1,
S_DATA, S_CLOCK, M0:M8
TEST_CLK
VCO_SEL, XTAL_SEL, MR,
S_LOAD, nP_LOAD, N0:N1,
S_DATA, S_CLOCK, M0:M8
TEST_CLK
M0-M4, M6-M8, N0, N1, MR,
S_CLOCK, TEST_CLK,
S_DATA, S_LOAD, nP_LOAD
M5, XTAL_SEL, VCO_SEL
IIL
Input
Low Current
Minimum
Typical
M0-M4, M6-M8, N0, N1, MR,
S_CLOCK, TEST_CLK,
S_DATA, S_LOAD, nP_LOAD
VCC = 3.465V,
VIN = 0V
-5
µA
M5, XTAL_SEL, VCO_SEL
VCC = 3.465V,
VIN = 0V
-150
µA
2. 6
V
VOH
Output
High Voltage
TEST; NOTE 1
VOL
Output
Low Voltage
TEST; NOTE 1
0.5
V
NOTE 1: Outputs terminated with 50Ω to VCCO/2.
84321AY
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REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
TABLE 4C. LVPECL DC CHARACTERISTICS, VCC = VCCA = VCCO = 3.3V±5%, TA = 0°C TO 70°C
Symbol
Parameter
Maximum
Units
VOH
Output High Voltage; NOTE 1
Test Conditions
Minimum
VCCO - 1.4
Typical
VCCO - 1.0
V
VOL
Output Low Voltage; NOTE 1
VCCO - 2.0
VCCO - 1.7
V
1.0
V
Maximum
Units
Peak-to-Peak Output Voltage Swing
0.6
VSWING
NOTE 1: Outputs terminated with 50 Ω to VCCO - 2V. See "Parameter Measurement Information" section,
"3.3V Output Load Test Circuit".
TABLE 5. INPUT FREQUENCY CHARACTERISTICS, VCC = VCCA = VCCO = 3.3V±5%, TA = 0°C TO 70°C
Symbol Parameter
Test Conditions
Minimum
Typical
TEST_CLK; NOTE 1
14
40
MHz
XTAL_IN, XTAL_OUT;
Input Frequency
14
40
MHz
fIN
NOTE 1
S_CLOCK
50
MHz
NOTE 1: For the input crystal and TEST_CLK frequency range, the M value must be set for the VCO to operate within
the 620MHz to 780MHz range. Using the minimum input frequency of 14MHz, valid values of M are 45 ≤ M ≤ 55.
Using the maximum frequency of 40MHz, valid values of M are 16 ≤ M ≤ 19.
TABLE 6. CRYSTAL CHARACTERISTICS
Parameter
Test Conditions
Minimum
Mode of Oscillation
Typical Maximum
Units
Fundamental
Frequency
14
40
MHz
Equivalent Series Resistance (ESR)
50
Ω
Shunt Capacitance
7
pF
Drive Level
1
mW
TABLE 7. AC CHARACTERISTICS, VCC = VCCA = VCCO = 3.3V±5%, TA = 0°C TO 70°C
Symbol Parameter
Test Conditions
FOUT
Output Frequency
tjit(per)
Period Jitter, RMS; NOTE 1
tsk(o)
Output Skew; NOTE 2, 3
tR / tF
Output Rise/Fall Time
tS
Setup Time
Minimum
Typical
103.3
3
20% to 80%
200
Units
260
MH z
4.5
ps
15
ps
700
ps
M, N to nP_LOAD
5
ns
S_DATA to S_CLOCK
5
ns
S_CLOCK to S_LOAD
5
ns
M, N to nP_LOAD
5
ns
S_DATA to S_CLOCK
5
ns
tH
Hold Time
o dc
Output Duty Cycle
S_CLOCK to S_LOAD
5
45
PLL Lock Time
tLOCK
See Parameter Measurement Information section.
NOTE 1: Jitter performance using XTAL inputs.
NOTE 2: Defined as skew between outputs at the same supply voltage and with equal load conditions.
Measured at the output differential cross points.
NOTE 3: This parameter is defined in accordance with JEDEC Standard 65.
84321AY
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7
ns
55
%
1
ms
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
TYPICAL PHASE NOISE
0
-10
25MHz Input
-20
RMS Phase Noise Jitter
12K to 20MHz = 3.0ps (typical)
-30
-40
Z
(dBc
H )
PHASE NOISE
-50
-60
-70
-80
-90
156.25MHz
125MHz
-100
-110
-120
-130
-140
-150
10
100
1k
10k
100k
1M
10M
OFFSET FREQUENCY (HZ)
0
-10
25.5MHz Input
-20
RMS Phase Noise Jitter
12K to 20MHz = 3.0ps (typical)
-30
-40
-60
Z
(dBc
H )
PHASE NOISE
-50
-70
-80
212.5MHz
-90
-100
-110
-120
-130
106.25MHz
-140
-150
10
100
1k
10k
100k
1M
10M
OFFSET FREQUENCY (HZ)
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REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
PARAMETER MEASUREMENT INFORMATION
2V
VCC ,
VCCA, VCCO
Qx
SCOPE
nFOUTx
FOUTx
LVPECL
nFOUTy
nQx
VEE
FOUTy
tsk(o)
-1.3V ± 0.165V
3.3V OUTPUT LOAD AC TEST CIRCUIT
OUTPUT SKEW
VOH
80%
80%
VREF
VSW I N G
Clock
Outputs
VOL
1σ contains 68.26% of all measurements
2σ contains 95.4% of all measurements
3σ contains 99.73% of all measurements
4σ contains 99.99366% of all measurements
6σ contains (100-1.973x10-7)% of all measurements
20%
20%
tR
tF
Histogram
Reference Point
Mean Period
(Trigger Edge)
(First edge after trigger)
PERIOD JITTER
OUTPUT RISE/FALL TIME
nFOUTx
FOUTx
t PW
t
odc =
PERIOD
t PW
x 100%
t PERIOD
OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
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REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
APPLICATION INFORMATION
TERMINATION
FOR
LVPECL OUTPUTS
The clock layout topology shown below is a typical termination for LVPECL outputs. The two different layouts mentioned
are recommended only as guidelines.
drive 50Ω transmission lines. Matched impedance techniques
should be used to maximize operating frequency and minimize
signal distortion. Figures 2A and 2B show two different layouts
which are recommended only as guidelines. Other suitable clock
layouts may exist and it would be recommended that the board
designers simulate to guarantee compatibility across all printed
circuit and clock component process variations.
FOUT and nFOUT are low impedance follower outputs that
generate ECL/LVPECL compatible outputs. Therefore, terminating resistors (DC current path to ground) or current sources
must be used for functionality. These outputs are designed to
3.3V
Zo = 50Ω
125Ω
FOUT
FIN
125Ω
Zo = 50Ω
Zo = 50Ω
FOUT
50Ω
1
RTT =
Z
((VOH + VOL) / (VCC – 2)) – 2 o
FIN
50Ω
Zo = 50Ω
- 2V
VVCC
CC - 2V
RTT
84Ω
FIGURE 2A. LVPECL OUTPUT TERMINATION
84Ω
FIGURE 2B. LVPECL OUTPUT TERMINATION
CRYSTAL INPUT INTERFACE
The ICS84321 has been characterized with 18pF parallel resonant crystals. The capacitor values shown in Figure 3 below were
determined using a 25MHz, 18pF parallel resonant crystal and
were chosen to minimize the ppm error. These same capacitor
values will tune any 18pF parallel resonant crystal over the frequency range of 14MHz to 40MHz providing the other parameters specified in Table 6, Crystal Characteristics, are satisfied.
XTAL_IN
C1
18p
X1
18pF Parallel Crystal
XTAL_OUT
C2
22p
Figure 3. CRYSTAL INPUt INTERFACE
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REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins
are vulnerable to random noise. The ICS84321 provides separate power supplies to isolate any high switching
noise from the outputs to the internal PLL. VCC, VCCA, and VCCO
should be individually connected to the power supply
plane through vias, and bypass capacitors should be
used for each pin. To achieve optimum jitter performance,
power supply isolation is required. Figure 4 illustrates how
a 24Ω resistor along with a 10μF and a .01μF bypass
capacitor should be connected to each VCCA pin.
3.3V
VCC
.01μF
24Ω
VCCA
10 μF
.01μF
FIGURE 4. POWER SUPPLY FILTERING
LAYOUT GUIDELINE
The schematic of the ICS84321 layout example used in this layout guideline is shown in Figure 5A. The ICS84321 recommended
PCB board layout for this example is shown in Figure 5B. This
layout example is used as a general guideline. The layout in the
actual system will depend on the selected component types, the
density of the components, the density of the traces, and the
stack up of the P.C. board.
C1
C2
M5
M6
M7
M8
N0
N1
nc
VEE
VCC
ICS84321
X_OUT
T_CLK
nXTAL_SEL
VCCA
S_LOAD
S_DATA
S_CLOCK
MR
TEST
VCC
FOUT1
nFOUT1
VCCO
FOUT0
nFOUT0
VEE
1
2
3
4
5
6
7
8
9
10
11
12
VCC
13
FOUT
14
FOUTN 15
16
U1
M4
M3
M2
M1
M0
VCO_SEL
nP_LOAD
X_IN
32
31
30
29
28
27
26
25
X1
VCC
24
23
22
21
20
19
18
17
R7
10
REF_IN
XTAL_SEL
VCCA
S_LOAD
S_DATA
S_CLOCK
C11
0.01u
C16
10u
VCC
R1
125
R3
125
Zo = 50 Ohm
C14
0.1u
C15
0.1u
+
Zo = 50 Ohm
-
R2
84
FIGURE 5A. SCHEMATIC
84321AY
OF
RECOMMENDED LAYOUT
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11
R4
84
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
The following component footprints are used in this layout
example:
• The differential 50Ω output traces should have the
same length.
All the resistors and capacitors are size 0603.
• Avoid sharp angles on the clock trace. Sharp angle
turns cause the characteristic impedance to change on
the transmission lines.
POWER
AND
GROUNDING
Place the decoupling capacitors C14 and C15, as close as possible to the power pins. If space allows, placement of the
decoupling capacitor on the component side is preferred. This
can reduce unwanted inductance between the decoupling capacitor and the power pin caused by the via.
• Keep the clock traces on the same layer. Whenever possible, avoid placing vias on the clock traces. Placement
of vias on the traces can affect the trace characteristic
impedance and hence degrade signal integrity.
Maximize the power and ground pad sizes and number of vias
capacitors. This can reduce the inductance between the power
and ground planes and the component power and ground pins.
• To prevent cross talk, avoid routing other signal traces in
parallel with the clock traces. If running parallel traces is
unavoidable, allow a separation of at least three trace
widths between the differential clock trace and the other
signal trace.
The RC filter consisting of R7, C11, and C16 should be placed
as close to the VCCA pin as possible.
• Make sure no other signal traces are routed between the
clock trace pair.
CLOCK TRACES
• The matching termination resistors should be located as
close to the receiver input pins as possible.
AND
TERMINATION
Poor signal integrity can degrade the system performance or
cause system failure. In synchronous high-speed digital systems,
the clock signal is less tolerant to poor signal integrity than other
signals. Any ringing on the rising or falling edge or excessive ring
back can cause system failure. The shape of the trace and the
trace delay might be restricted by the available space on the board
and the component location. While routing the traces, the clock
signal traces should be routed first and should be locked prior to
routing other signal traces.
CRYSTAL
The crystal X1 should be located as close as possible to the pins
25 (XTAL_IN) and 24 (XTAL_OUT). The trace length between the
X1 and U1 should be kept to a minimum to avoid unwanted
parasitic inductance and capacitance. Other signal traces should
not be routed near the crystal traces.
GND
X1
C1
C2
VCC
VIA
U1
PIN 1
C16
C11
VCCA
R7
Close to the input
pins of the
receiver
TL1N
C15
TL1
C14
TL1
R1
R2
TL1N
R3
R4
TL1, TL21N are 50 Ohm
traces and equal length
FIGURE 5B. PCB BOARD LAYOUT
84321AY
FOR
ICS84321
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12
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
POWER CONSIDERATIONS
This section provides information on power dissipation and junction temperature for the ICS84321.
Equations and example calculations are also provided.
1. Power Dissipation.
The total power dissipation for the ICS84321 is the sum of the core power plus the power dissipated in the load(s).
The following is the power dissipation for VCC = 3.3V + 5% = 3.465V, which gives worst case results.
NOTE: Please refer to Section 3 for details on calculating power dissipated in the load.
•
•
Power (core)MAX = VCC_MAX * IEE_MAX = 3.465V * 178mA = 616.8mW
Power (outputs)MAX = 30.2mW/Loaded Output pair
If all outputs are loaded, the total power is 2 * 30.2mW = 60.4mW
Total Power_MAX (3.465V, with all outputs switching) = 616.8W + 60.4mW = 677.2mW
2. Junction Temperature.
Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad and directly affects the reliability of the
device. The maximum recommended junction temperature for HiPerClockSTM devices is 125°C.
The equation for Tj is as follows: Tj = θJA * Pd_total + TA
Tj = Junction Temperature
θJA = Junction-to-Ambient Thermal Resistance
Pd_total = Total Device Power Dissipation (example calculation is in section 1 above)
TA = Ambient Temperature
In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance θJA must be used. Assuming a
moderate air flow of 200 linear feet per minute and a multi-layer board, the appropriate value is 42.1°C/W per Table 8 below.
Therefore, Tj for an ambient temperature of 70°C with all outputs switching is:
70°C + 0.677W * 42.1°C/W = 98.5°C. This is well below the limit of 125°C.
This calculation is only an example. Tj will obviously vary depending on the number of loaded outputs, supply voltage, air flow,
and the type of board (single layer or multi-layer).
TABLE 8. THERMAL RESISTANCE θJA
FOR
32-PIN LQFP, FORCED CONVECTION
θ JA by Velocity (Linear Feet per Minute)
Single-Layer PCB, JEDEC Standard Test Boards
Multi-Layer PCB, JEDEC Standard Test Boards
0
200
500
67.8°C/W
47.9°C/W
55.9°C/W
42.1°C/W
50.1°C/W
39.4°C/W
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
84321AY
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REV. B JUNE 9, 2005
ICS84321
Integrated
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260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
3. Calculations and Equations.
The purpose of this section is to derive the power dissipated into the load.
LVPECL output driver circuit and termination are shown in Figure 6.
VCCO
Q1
VOUT
RL
50
VCCO - 2V
FIGURE 6. LVPECL DRIVER CIRCUIT
AND
TERMINATION
To calculate worst case power dissipation into the load, use the following equations which assume a 50Ω load, and a termination
voltage of V - 2V.
CCO
•
For logic high, VOUT = VOH_MAX = VCCO_MAX – 1.0V
(V
CCO_MAX
•
-V
OH_MAX
) = 1.0V
For logic low, VOUT = V
=V
OL_MAX
(V
CCO_MAX
-V
OL_MAX
CCO_MAX
– 1.7V
) = 1.7V
Pd_H is power dissipation when the output drives high.
Pd_L is the power dissipation when the output drives low.
Pd_H = [(V
OH_MAX
– (V
CCO_MAX
- 2V))/R ] * (V
CCO_MAX
L
-V
OH_MAX
) = [(2V - (V
CCO_MAX
))/R ] * (V
-V
OH_MAX
CCO_MAX
L
-V
)=
OH_MAX
[(2V - 1V)/50Ω) * 1V = 20.0mW
Pd_L = [(V
OL_MAX
– (V
CCO_MAX
- 2V))/R ] * (V
L
CCO_MAX
-V
OL_MAX
) = [(2V - (V
CCO_MAX
-V
OL_MAX
))/R ] * (V
L
CCO_MAX
-V
OL_MAX
)=
[(2V - 1.7V)/50Ω) * 1.7V = 10.2mW
Total Power Dissipation per output pair = Pd_H + Pd_L = 30.2mW
84321AY
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14
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
RELIABILITY INFORMATION
TABLE 9. θJAVS. AIR FLOW TABLE
FOR
32 LEAD LQFP
θ JA by Velocity (Linear Feet per Minute)
Single-Layer PCB, JEDEC Standard Test Boards
Multi-Layer PCB, JEDEC Standard Test Boards
0
200
500
67.8°C/W
47.9°C/W
55.9°C/W
42.1°C/W
50.1°C/W
39.4°C/W
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
TRANSISTOR COUNT
The transistor count for ICS84321 is: 3744
84321AY
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15
REV. B JUNE 9, 2005
ICS84321
Integrated
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Systems, Inc.
PACKAGE OUTLINE - Y SUFFIX
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
FOR
32 LEAD LQFP
TABLE 10. PACKAGE DIMENSIONS
JEDEC VARIATION
ALL DIMENSIONS IN MILLIMETERS
BBA
SYMBOL
MINIMUM
NOMINAL
MAXIMUM
32
N
A
--
--
1.60
A1
0.05
--
0.15
A2
1.35
1.40
1.45
b
0.30
0.37
0.45
c
0.09
--
0.20
D
9.00 BASIC
D1
7.00 BASIC
D2
5.60 Ref.
E
9.00 BASIC
E1
7.00 BASIC
E2
5.60 Ref.
e
0.80 BASIC
0.75
L
0.45
0.60
θ
0°
--
7°
ccc
--
--
0.10
Reference Document: JEDEC Publication 95, MS-026
84321AY
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16
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
TABLE 11. ORDERING INFORMATION
Part/Order Number
Marking
Package
Shipping Packaging
Temperature
ICS84321AY
ICS84321AY
32 Lead LQFP
tray
0°C to 70°C
ICS84321AYT
ICS84321AY
32 Lead LQFP
1000 tape & reel
0°C to 70°C
ICS84321AYLF
TBD
32 Lead "Lead-Free" LQFP
tray
0°C to 70°C
ICS84321AYLFT
TB D
32 Lead "Lead-Free" LQFP
1000 tape & reel
0°C to 70°C
NOTE: Par ts that are ordered with an "LF" suffix to the par t number are the Pb-Free configuration and are RoHS compliant.
The aforementioned trademark, HiPerClockS™ is a trademark of Integrated Circuit Systems, Inc. or its subsidiaries in the United States and/or other countries.
While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems, Incorporated (ICS) assumes no responsibility for either its use
or for 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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17
REV. B JUNE 9, 2005
ICS84321
Integrated
Circuit
Systems, Inc.
260MHZ, CRYSTAL-TO-3.3V DIFFERENTIAL
LVPECL FREQUENCY SYNTHESIZER
REVISION HISTORY SHEET
Rev
Table
A
A
T11
B
84321AY
T6
T11
Page
1
1
10
17
1
2
7
17
Description of Change
Features section - RMS period jitter bullet, corrected typo from 2.5ps to 3ps.
Features section - add Lead-Free bullet.
Updated LVPECL Output Termination drawings.
Ordering Information table - added Lead-Free par t number.
Removed sentence from General Description.
Updated Figure 1.
Cr ystal Characteristics Table - added Drive Level.
Ordering Information Table - added Lead-Free note.
Rename XTAL1/2 to XTAL_IN/XTAL_OUT throughout the datasheet.
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18
Date
10/8/03
2/11/05
6/9/05
REV. B JUNE 9, 2005