CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
Two Output, Integrated VCO, Low-Jitter Clock Generator
Check for Samples: CDCM61002
FEATURES
1
•
2
•
•
•
•
•
•
•
•
•
•
•
•
One Crystal/LVCMOS Reference Input
Including 24.8832 MHz, 25 MHz, and
26.5625 MHz
Input Frequency Range: 21.875 MHz to
28.47 MHz
On-Chip VCO Operates in Frequency Range of
1.75 GHz to 2.05 GHz
2x Output Available:
– Pin-Selectable Between LVPECL, LVDS, or
2-LVCMOS; Operates at 3.3 V
LVCMOS Bypass Output Available
Output Frequency Selectable by /1, /2, /3, /4, /6,
/8 from a Single Output Divider
Supports Common LVPECL/LVDS Output
Frequencies:
– 62.5 MHz, 74.25 MHz, 75 MHz, 77.76 MHz,
100 MHz, 106.25 MHz, 125 MHz, 150 MHz,
155.52 MHz, 156.25 MHz, 159.375 MHz,
187.5 MHz, 200 MHz, 212.5 MHz, 250 MHz,
311.04 MHz, 312.5 MHz, 622.08 MHz,
625 MHz
Supports Common LVCMOS Output
Frequencies:
– 62.5 MHz, 74.25 MHz, 75 MHz, 77.76 MHz,
100 MHz, 106.25 MHz, 125 MHz, 150 MHz,
155.52 MHz, 156.25 MHz, 159.375 MHz,
187.5 MHz, 200 MHz, 212.5 MHz, 250 MHz
Output Frequency Range: 43.75 MHz to
683.264 MHz (See Table 3)
Internal PLL Loop Bandwidth: 400 kHz
High-Performance PLL Core:
– Phase Noise typically at –146 dBc/Hz at
5-MHz Offset for 625-MHz LVPECL Output
– Random Jitter typically at 0.509 ps, RMS
(10 kHz to 20 MHz) for 625-MHz LVPECL
Output
Output Duty Cycle Corrected to 50% (± 5%)
Low Output Skew of 20 ps on LVPECL Outputs
•
•
•
•
•
•
Divider Programming Using Control Pins:
– Two Pins for Prescaler/Feedback Divider
– Three Pins for Output Divider
– Two Pins for Output Select
Chip Enable Control Pin Available
3.3-V Core and I/O Power Supply
Industrial Temperature Range: –40°C to +85°C
5-mm × 5-mm, 32-pin, QFN (RHB) Package
ESD Protection Exceeds 2 kV (HBM)
APPLICATIONS
•
•
Low Jitter Clock Driver for High-End Datacom
Applications Including SONET, Ethernet, Fibre
Channel, Serial ATA, and HDTV
Cost-Effective High-Frequency Crystal
Oscillator Replacement
DESCRIPTION
The CDCM61002 is a highly versatile, low-jitter
frequency synthesizer that can generate two low-jitter
clock outputs, selectable between low-voltage
positive emitter coupled logic (LVPECL), low-voltage
differential signaling (LVDS), or low-voltage
complementary
metal
oxide
semiconductor
(LVCMOS) outputs, from a low-frequency crystal or
LVCMOS input for a variety of wireline and data
communication applications. The CDCM61002
features an onboard PLL that can be easily
configured solely through control pins. The overall
output random jitter performance is less than 1ps,
RMS (from 10 kHz to 20 MHz), making this device a
perfect choice for use in demanding applications such
as SONET, Ethernet, Fibre Channel, and SAN. The
CDCM61002 is available in a small, 32-pin, 5-mm ×
5-mm QFN package.
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
DESCRIPTION, CONTINUED
The CDCM61002 is a high-performance, low phase noise, fully-integrated voltage-controlled oscillator (VCO)
clock synthesizer with two universal output buffers that can be configured to be LVPECL, LVDS, or LVCMOS
compatible. Each universal output can also be converted to two LVCMOS outputs. Additionally, an LVCMOS
bypass output clock is available in an output configuration which can help with crystal loading in order to achieve
an exact desired input frequency. It has one fully-integrated, low-noise, LC-based VCO that operates in the 1.75
GHz to 2.05 GHz range.
The phase-locked loop (PLL) synchronizes the VCO with respect to the input, which can either be a
low-frequency crystal. The outputs share an output divider sourced from the VCO core. All device settings are
managed through a control pin structure, which has two pins that control the prescaler and feedback divider,
three pins that control the output divider, two pins that control the output type, and one pin that controls the
output enable. Any time the PLL settings (including the input frequency, prescaler divider, or feedback divider)
are altered, a reset must be issued through the Reset control pin (active low for device reset). The reset initiates
a PLL recalibration process to ensure PLL lock. When the device is in reset, the outputs and dividered are turned
off.
The output frequency (fOUT) is proportional to the frequency of the input clock (fIN). The feedback divider, output
divider, and VCO frequency set fOUT with respect to fIN. For a configuration setting for common wireline and
datacom applications, refer toTable 2. For other applications, use Equation 1 to calculate the exact crystal
oscillator frequency required for the desired output.
Output Divider f
fIN =
Feedback Divider OUT
(1)
(
(
The output divider can be chosen from 1, 2, 3, 4, 6, or 8 through the use of control pins. Feedback divider and
prescaler divider combinations can be chosen from 25 and 3, 24 and 3, 20 and 4, or 15 and 5, respectively, also
through the use of control pins. Figure 1 shows a high-level block diagram of the CDCM61002.
The device operates in a 3.3-V supply environment and is characterized for operation from –40°C to +85°C.
RSTN
PR[1...0]
2
OD[2...0]
3
CDCM61002
Feedback
Divider
Prescaler
VCO
Output Divider
PFD
Charge Pump
Loop Filter
Crystal/
LVCMOS
Output
Driver
LVPECL/
LVCMOS/
LVDS
Output
Driver
LVPECL/
LVCMOS/
LVDS
3.3 V
LVCMOS
CE
2
OS[1...0]
Figure 1. CDCM61002 Block Diagram
2
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
AVAILABLE OPTIONS (1)
TA
–40°C to +85°C
(1)
PACKAGED DEVICES
FEATURES (2)
CDCM61002RHBT
32-pin QFN (RHB) package, small tape and reel
CDCM61002RHBR
32-pin QFN (RHB) package, tape and reel
For the most current specifications and package information, see the Package Option Addendum located at the end of this data sheet or
refer to our web site at www.ti.com.
These packages conform to Lead (Pb)-free and green manufacturing specifications. Additional details including specific material
contentcan be accessed at www.ti.com/leadfree. GREEN: TI defines Green to mean Lead (Pb)-Free and in addition, uses less package
materials that do not contain halogens, including bromine (Br), or antimony (Sb) above 0.1%of total product weight. N/A: Not yet
available Lead (Pb)-Free; for estimated conversion dates, go to www.ti.com/leadfree. Pb-FREE: TI defines Lead (Pb)-Free to mean
RoHS compatible, including a lead concentration that does not exceed 0.1% of total product weight, and, if designed to be soldered,
suitable for use in specified lead-free soldering processes.
(2)
ABSOLUTE MAXIMUM RATINGS (1)
Over operating free-air temperature range (unless otherwise noted).
PARAMETER
VCC_OUT,
VCC_PLL1,
VCC_PLL2,
VCC_VCO,
VCC_IN
Supply voltage range (2)
VIN
Input voltage range (3)
VOUT
Output voltage range (3)
IIN
IOUT
TSTG
Storage temperature range
(1)
(2)
(3)
VALUE
UNIT
–0.5 to 4.6
V
–0.5 to (VCC_IN + 0.5)
V
–0.5 to (VCC_OUT + 0.5)
V
Input current
20
mA
Output current
50
mA
–65 to +150
°C
Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
condition is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All supply voltages must be supplied simultaneously.
Input and output negative voltage ratings may be exceeded if the input and output clamp-current ratings are observed.
RECOMMENDED OPERATING CONDITIONS
Over operating free-air temperature range (unless otherwise noted).
MIN
NOM
MAX
UNIT
VCC_OUT
Output supply voltage
PARAMETER
3.0
3.30
3.60
V
VCC_PLL1
PLL supply voltage
3.0
3.30
3.60
V
VCC_PLL2
PLL supply voltage
3.0
3.30
3.60
V
VCC_VCO
On-chip VCO supply voltage
3.0
3.30
3.60
V
VCC_IN
Input supply voltage
3.0
3.30
3.60
V
TA
Ambient temperature
–40
+85
°C
DISSIPATION RATINGS (1) (2)
VALUE
PARAMETER
θJA
Thermal resistance, junction-to-ambient
θJP (3)
(1)
(2)
(3)
Thermal resistance, junction-to-pad
TEST
CONDITIONS
4 × 4 VIAS
ON PAD
UNIT
0 LFM
35
°C/W
4
°C/W
The package thermal resistance is calculated in accordance with JESD 51 and JEDEC 2S2P (high-K board).
Connected to GND with nine thermal vias (0.3-mm diameter).
θJP (junction-to-pad) is used for the QFN package, because the primary heat flow is from the junction to the GND pad of the QFN
package.
Copyright © 2009–2011, Texas Instruments Incorporated
3
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
ELECTRICAL CHARACTERISTICS
At VCC = 3 V to 3.6 V and TA = –40°C to +85°C, unless otherwise noted.
CDCM61002
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
Control Pin LVCMOS Input Characteristics
VIH
Input high voltage
VIL
Input low voltage
IIH
Input high current
IIL
Input low current
0.6VCC
V
0.4VCC
V
VCC = 3.6 V, VIL = 0 V
200
μA
VCC = 3 V, VIH = 3.6 V
–200
μA
21.875
28.47
MHz
43.75
250
MHz
LVCMOS Output Characteristics (1) (See Figure 9 and Figure 10)
fOSC_OUT
Bypass output frequency
fOUT
Output frequency
VOH
Output high voltage
VCC = min to max, IOH = –100 μA
VOL
Output low voltage
VCC = min to max, IOL = 100 μA
tRJIT
RMS phase jitter
250 MHz (10 kHz to 20 MHz)
tSLEW-RATE
Output rise/fall slew rate
20% to 80%
ODC
Output duty cycle
tSKEW
Skew between outputs
ICC,
LVCMOS
Device current, LVCMOS
VCC –0.5
V
0.3
V
0.85 ps, RMS
2.4
V/ns
45%
fIN = 25 MHz, fOUT = 250 MHz,
CL = 5 pF
55%
120
50
ps
140
mA
MHz
LVPECL Output Characteristics (2) (See Figure 11 and Figure 12)
fOUT
Output frequency
VOH
Output high voltage
43.75
683.264
VCC –1.18
VCC –0.73
VOL
Output low voltage
V
VCC –2
VCC –1.55
V
|VOD|
Differential output voltage
tRJIT
RMS phase jitter
625 MHz (10 kHz to 20 MHz)
0.6
1.23
0.77 ps, RMS
V
tR/tF
Output rise/fall time
20% to 80%
175
ODC
Output duty cycle
tSKEW
Skew between outputs
ICC,
LVPECL
Device current, LVPECL
45%
fIN = 25 MHz, fOUT = 625 MHz
ps
55%
126
20
ps
144
mA
MHz
LVDS Output Characteristics (3) (See Figure 13 and Figure 14)
fOUT
Output frequency
43.75
683.264
|VOD|
Differential output voltage
0.247
0.454
ΔVOD
VDD magnitude change
VOS
Common-mode voltage
1.125
1.375
ΔVOS
VOS magnitude change
tRJIT
RMS phase jitter
625 MHz (10 kHz to 20 MHz)
tR/tF
Output rise/fall time
20% to 80%
ODC
Output duty cycle
tSKEW
Skew between outputs
ICC, LVDS
Device current, LVDS
(1)
(2)
(3)
4
50
50
mV
V
mV
0.73 ps, RMS
255
45%
fIN = 25 MHz, fOUT = 625 MHz
V
ps
55%
110
30
ps
125
mA
Figure 9 and Figure 10 show dc and ac test setups, respectively. Jitter measurements made using 25-MHz quartz crystal in.
Figure 11 and Figure 12 show dc and ac test setups, respectively. Jitter measurements made using 25-MHz quartz crystal in.
Figure 13 and Figure 14 show dc and ac test setups, respectively. Jitter measurements made using 25-MHz quartz crystal in.
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
TYPICAL OUTPUT PHASE NOISE CHARACTERISTICS
Over operating free-air temperature range (unless otherwise noted).
CDCM61002
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
250-MHz LVCMOS Output (1) (see Figure 10)
phn100
Phase noise at 100-Hz offset
–95
dBc/Hz
phn1k
Phase noise at 1-kHz offset
–110
dBc/Hz
phn10k
Phase noise at 10-kHz offset
–117
dBc/Hz
phn100k
Phase noise at 100-kHz offset
–120
dBc/Hz
phn1M
Phase noise at 1-MHz offset
–135
dBc/Hz
phn10M
Phase noise at 10-MHz offset
–148
dBc/Hz
phn20M
Phase noise at 20-MHz offset
–148
dBc/Hz
tRJIT
RMS phase jitter from 10 kHz to 20 MHz
544
fs, RMS
tPJIT
Total period jitter
27.4
ps, PP
tSTARTUP
Start-up time, power supply ramp time of 1 ms,
final frequency accuracy of ±10 ppm
2.25
ms
625-MHz LVPECL Output (2) (see Figure 12)
phn100
Phase noise at 100-Hz offset
–81
dBc/Hz
phn1k
Phase noise at 1-kHz offset
–101
dBc/Hz
phn10k
Phase noise at 10-kHz offset
–109
dBc/Hz
phn100k
Phase noise at 100-kHz offset
–112
dBc/Hz
phn1M
Phase noise at 1-MHz offset
–129
dBc/Hz
phn10M
Phase noise at 10-MHz offset
–146
dBc/Hz
phn20M
Phase noise at 20-MHz offset
–146
dBc/Hz
tRJIT
RMS phase jitter from 10 kHz to 20 MHz
509
fs, RMS
tPJIT
Total period jitter
26.9
ps, PP
tSTARTUP
Start-up time, power supply ramp time of 1 ms,
final frequency accuracy of ±10 ppm
2.25
ms
–88
dBc/Hz
625-MHz LVDS Output (3) (see Figure 14)
phn100
Phase noise at 100-Hz offset
phn1k
Phase noise at 1-kHz offset
–102
dBc/Hz
phn10k
Phase noise at 10-kHz offset
–109
dBc/Hz
phn100k
Phase noise at 100-kHz offset
–112
dBc/Hz
phn1M
Phase noise at 1-MHz offset
–129
dBc/Hz
phn10M
Phase noise at 10-MHz offset
–146
dBc/Hz
phn20M
Phase noise at 20-MHz offset
–146
dBc/Hz
tRJIT
RMS phase jitter from 10 kHz to 20 MHz
510
fs, RMS
tPJIT
Total period jitter
27
ps, PP
tSTARTUP
Start-up time, power supply ramp time of 1 ms,
final frequency accuracy of ±10 ppm
(1)
(2)
(3)
2.25
ms
Figure 10 shows test setup and uses 25-MHz quartz crystal in, VCC = 3.3 V, and TA = +25°C.
Figure 12 shows test setup and uses 25-MHz quartz crystal in, VCC = 3.3 V, and TA = +25°C.
Figure 14 shows test setup and uses 25-MHz quartz crystal, VCC = 3.3 V, and TA = +25°C.
Copyright © 2009–2011, Texas Instruments Incorporated
5
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
TYPICAL OUTPUT JITTER CHARACTERISTICS (1)
OUTPUT
FREQUENCY
(MHz)
INPUT (MHz)
tRJIT
tPJIT (psPP)
tRJIT
tPJIT (psPP)
tRJIT
tPJIT (psPP)
62.5
25
592
32.9
611
20.7
667
28.4
75
25
518
27.5
533
19.4
572
25.7
77.76
24.8832
506
29.2
526
20.9
567
26.9
100
25
507
24.5
510
20.7
533
26.5
106.25
26.5625
535
23.5
524
20.2
553
26.5
125
25
557
39.6
556
21.4
570
27.1
150
25
518
38.4
493
18.9
515
26.2
155.52
24.8832
498
36.9
486
19.8
502
26.7
(1)
6
LVCMOS OUTPUT
LVPECL OUTPUT
LVDS OUTPUT
156.25
25
510
37.7
503
20.7
518
26.5
159.375
26.5625
535
37.4
510
19.9
534
26.3
187.5
25
506
32.8
506
20.3
509
25.5
200
25
491
23.3
492
30
499
34.9
212.5
26.5625
520
47.8
509
30.8
530
37.3
250
25
544
27.4
541
21.4
550
27.5
311.04
24.8832
481
20.5
496
24.7
312.5
25
501
20.8
508
25.8
622.08
24.8832
492
27.2
500
27.2
625
25
515
26.9
509
27
Figure 10, Figure 12, and Figure 14 show LVCMOS, LVPECL, and LVDS test setups (respectively) using appropriate quartz crystal in,
VCC = 3.3 V, and TA = +25°C.
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
CRYSTAL CHARACTERISTICS
PARAMETER
MINIMUM
TYPICAL
Mode of oscillation
MAXIMUM
Fundamental
Frequency
21.875
Equivalent series resistance (ESR)
On-chip load capacitance
8
Drive level
0.1
Maximum shunt capacitance
UNIT
MHz
28.47
MHz
50
Ω
10
pF
1
mW
7
pF
DEVICE INFORMATION
NC
NC
NC
NC
NC
NC
PR1
PR0
RHB PACKAGE
QFN-32
(TOP VIEW)
32
31
30
29
28
27
26
25
VCC_OUT
1
24
NC
OUTN1
2
23
OSC_OUT
22
GND1
21
XIN
20
VCC_IN
19
REG_CAP1
OUTP1
3
VCC_OUT
4
OUTN0
5
OUTP0
6
CE
7
18
VCC_PLL1
NC
8
17
REG_CAP2
CDCM61002
Copyright © 2009–2011, Texas Instruments Incorporated
9
10
11
12
13
14
15
16
VCC_VCO
OS1
OS0
RSTN
OD0
OD1
OD2
VCC_PLL2
Thermal Pad
(must be soldered to ground)
7
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
PIN FUNCTIONS
PIN
NAME
DIRECTION (1)
PAD NO.
TYPE
VCC_OUT
1, 4
Power
3.3-V supply for the output buffer
VCC_PLL1
18
Power
3.3-V supply for the PLL circuitry
VCC_PLL2
16
Power
3.3-V supply for the PLL circuitry
VCC_VCO
9
Power
3.3-V supply for the internal VCO
VCC_IN
20
Power
3.3-V supply for the input buffers
GND1
22
Ground
Additional ground for device. (GND1 shorted on-chip to GND)
GND
Pad
Ground
Ground is on thermal pad. See Thermal
Management
.
XIN
21
Input
Parallel resonant crystal/LVCMOS input
OUTP0,
OUTN0
6, 5
Output
Differential output pair or two single-ended outputs
OUTP1,
OUTN1
3, 2
Output
Differential output pair or two single-ended outputs
OSC_OUT
23
Output
Bypass LVCMOS output
REG_CAP1
19
Output
Capacitor for internal regulator (connect to a 10-μF Y5V capacitor to
GND)
REG_CAP2
17
Output
Capacitor for internal regulator (connect to a 10-μF Y5V capacitor to
GND)
PR1, PR0
26, 25
Input
Pull-up
Prescaler and Feedback divider control pins (see Table 4)
OD2, OD1,
OD0
15, 14, 13
Input
Pull-up
Output divider control pins (see Table 5)
OS1, OS0
10, 11
Input
Pull-up
Output type select control pin (see Table 6)
7
Input
Pull-up
Chip enable control pin (see Table 7)
12
Input
Pull-up
Device reset (active low) (see Table 8)
CE
RSTN
8, 24, 27, 28,
29, 30, 31,
32
NC
(1)
DESCRIPTION
No connection
Pull-up refes to internal input resistors; see Pin Characteristics for typical values.
Table 1. PIN CHARACTERISTICS
SYMBOL
CIN
RPULLUP
8
PARAMETER
Input capacitance
Input pull-up resistor
MIN
TYP
MAX
8
10
150
UNIT
pF
kΩ
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
PACKAGE
Figure 2. RHB Package
Copyright © 2009–2011, Texas Instruments Incorporated
9
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
FUNCTIONAL BLOCK DIAGRAM
VCC_IN
VCC_PLL1
XO
LVCMOS
XIN
VCC_PLL2
Phase
Frequency
Detector
21.875 MHz
to 28.47 MHz
VCC_VCO
VCC_VDD
VCC_OUT
Loop Filter
Charge
Pump
224 mA
400 kHz
¸15
FB_MUX
¸5
VCO
1.75 GHz
to 2.05 GHz
¸20
¸4
¸24
RSTN
¸3
Prescaler
Divider
¸25
Feedback
Divider
LVCMOS
¸1
PR1
DIV_MUX
PR0
¸2
LVPECL
OUTP[1...0]
¸3
2
¸4
LVDS
OUTN[1...0]
¸6
REG_CAP1
¸8
LVCMOS
Output
Divider
REG_CAP2
LVCMOS
OSC_OUT
CDCM61002
CE
10
GND1
OD2 OD1 OD0
OS1 OS0
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
DEVICE CONFIGURATION
Table 2. Common Configuration
INPUT (MHz)
PRESCALER
DIVIDER
FEEDBACK
DIVIDER
VCO
FREQUENCY
(MHz)
OUTPUT
DIVIDER
OUTPUT
FREQUENCY
(MHz)
25
4
20
2000
8
62.5
GigE
24.75
3
24
1782
8
74.25
HDTV
25
3
24
1800
8
75
SATA
24.8832
3
25
1866.24
8
77.76
APPLICATION
SONET
25
3
24
1800
6
100
26.5625
3
24
1912.5
6
106.25
PCI Express
25
4
20
2000
4
125
GigE
SATA
Fibre Channel
25
3
24
1800
4
150
24.8832
3
25
1866.24
4
155.52
SONET
25
3
25
1875
4
156.25
10 GigE
26.5625
3
24
1912.5
4
159.375
10-G Fibre Channel
25
5
15
1875
2
187.5
25
3
24
1800
3
200
26.5625
3
24
1912.5
3
212.5
12 GigE
PCI Express
4-G Fibre Channel
25
4
20
2000
2
250
24.8832
3
25
1866.24
2
311.04
GigE
SONET
25
3
25
1875
2
312.5
XGMII
24.8832
3
25
1866.24
1
622.08
SONET
25
3
25
1875
1
625
10 GigE
Table 3. Generic Configuration
INPUT FREQUENCY
RANGE (MHz)
PRESCALER
DIVIDER
FEEDBACK
DIVIDER
VCO FREQUENCY
RANGE (MHz)
OUTPUT DIVIDER
OUTPUT
FREQUENCY
RANGE (MHz)
21.875 to 25.62
4
20
1750 to 2050
8
54.6875 to 64.05
21.875 to 25.62
4
20
1750 to 2050
6
72.92 to 85.4
21.875 to 25.62
4
20
1750 to 2050
4
109.375 to 128.1
21.875 to 25.62
4
20
1750 to 2050
3
145.84 to 170.8
21.875 to 25.62
4
20
1750 to 2050
2
218.75 to 256.2
21.875 to 25.62
4
20
1750 to 2050
1
437.5 to 512.4
23.33 to 27.33
3
25
1750 to 2050
8
72.906 to 85.408
23.33 to 27.33
3
25
1750 to 2050
6
97.21 to 113.875
23.33 to 27.33
3
25
1750 to 2050
4
145.812 to 170.816
23.33 to 27.33
3
25
1750 to 2050
3
194.42 to 227.75
23.33 to 27.33
3
25
1750 to 2050
2
291.624 to 341.632
23.33 to 27.33
3
25
1750 to 2050
1
583.248 to 683.264
23.33 to 27.33
5
15
1750 to 2050
8
43.75 to 51.25
23.33 to 27.33
5
15
1750 to 2050
6
58.33 to 68.33
23.33 to 27.33
5
15
1750 to 2050
4
87.5 to 102.5
23.33 to 27.33
5
15
1750 to 2050
3
116.66 to 136.66
23.33 to 27.33
5
15
1750 to 2050
2
175 to 205
23.33 to 27.33
5
15
1750 to 2050
1
350 to 410
24.305 to 28.47
3
24
1750 to 2050
8
72.915 to 85.41
24.305 to 28.47
3
24
1750 to 2050
6
97.22 to 113.88
24.305 to 28.47
3
24
1750 to 2050
4
145.83 to 170.82
Copyright © 2009–2011, Texas Instruments Incorporated
11
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
Table 3. Generic Configuration (continued)
INPUT FREQUENCY
RANGE (MHz)
PRESCALER
DIVIDER
FEEDBACK
DIVIDER
VCO FREQUENCY
RANGE (MHz)
OUTPUT DIVIDER
OUTPUT
FREQUENCY
RANGE (MHz)
24.305 to 28.47
3
24
1750 to 2050
3
194.44 to 227.76
24.305 to 28.47
3
24
1750 to 2050
2
291.66 to 341.64
24.305 to 28.47
3
24
1750 to 2050
1
583.32 to 683.28
Table 4. Programmable Prescaler and Feedback Divider Settings
CONTROL INPUTS
PFD FREQUENCY
PR1
PR0
PRESCALER
DIVIDER
FEEDBACK
DIVIDER
MINIMUM
MAXIMUM
0
0
3
24
24.305
28.47
0
1
5
15
23.33
27.33
1
0
3
25
23.33
27.33
1
1
4
20
21.875
25.62
Table 5. Programmable Output Divider
CONTROL INPUTS
OD2
OD1
OD0
OUTPUT DIVIDER
0
0
0
1
0
0
1
2
0
1
0
3
0
1
1
4
1
0
0
Reserved
1
0
1
6
1
1
0
Reserved
1
1
1
8
Table 6. Programmable Output Type
CONTROL INPUTS
OS1
OS0
OUTPUT TYPE
0
0
LVCMOS, OSC_OUT Off
0
1
LVDS, OSC_OUT Off
1
0
LVPECL, OSC_OUT Off
1
1
LVPECL, OSC_OUT On
Table 7. Output Enable
CONTROL INPUT
CE
OPERATING
CONDITION
0
Power Down
Hi-Z
1
Normal
Active
OUTPUT
Table 8. Reset
CONTROL INPUT
12
RSTN
OPERATING
CONDITION
OUTPUT
0
Device Reset
Hi-Z
0→1
PLL Recalibration
Hi-Z
1
Normal
Active
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
TYPICAL CHARACTERISTICS
Over operating free-air temperature range (unless otherwise noted).
TYPICAL CURRENT CONSUMPTION FOR LVPECL OUTPUT
vs OUTPUT FREQUENCY
145
Output-divide-by-8
Output-divide-by-6
Output-divide-by-4
140
Output-divide-by-3
Supply CUrrent (mA)
Output-divide-by-2
Output-divide-by-1
135
130
125
120
0
200
400
600
800
Output Frequency (MHz)
Figure 3.
TYPICAL CURRENT CONSUMPTION FOR LVDS OUTPUT
vs OUTPUT FREQUENCY
130
Output-divide-by-8
Output-divide-by-6
Output-divide-by-4
125
Output-divide-by-3
Supply CUrrent (mA)
Output-divide-by-2
Output-divide-by-1
120
115
110
105
0
200
400
600
800
Output Frequency (MHz)
Figure 4.
Copyright © 2009–2011, Texas Instruments Incorporated
13
CDCM61002
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www.ti.com
TYPICAL CHARACTERISTICS (continued)
Over operating free-air temperature range (unless otherwise noted).
TYPICAL CURRENT CONSUMPTION FOR LVCMOS OUTPUT
WITH 5-pF LOAD vs OUTPUT FREQUENCY
130
125
Supply Current (mA)
120
115
110
105
Output-divide-by-8
100
Output-divide-by-6
Output-divide-by-4
95
Output-divide-by-3
Output-divide-by-2
90
0
50
100
150
200
250
300
Output Frequency (MHz)
Figure 5.
TYPICAL LVPECL DIFFERENTIAL OUTPUT VOLTAGE
vs OUTPUT FREQUENCY
0.77
Differential Output Voltage, VOD (V)
0.76
0.75
0.74
0.73
0.72
0.71
0.70
0
100
200
300
400
500
600
700
Output Frequency (MHz)
Figure 6.
14
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CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
TYPICAL CHARACTERISTICS (continued)
Over operating free-air temperature range (unless otherwise noted).
TYPICAL LVDS DIFFERENTIAL OUTPUT VOLTAGE
vs OUTPUT FREQUENCY
0.42
Differential Output Voltage, VDO (V)
0.40
0.38
0.36
0.34
0.32
0.30
0
100
200
300
400
500
600
700
Output Frequency (MHz)
Figure 7.
TYPICAL LVCMOS OUTPUT VOLTAGE WITH 5-pF LOAD
vs OUTPUT FREQUENCY
3.30
Output Voltage, VOUT (V)
3.25
3.20
3.15
3.10
3.05
3.00
50
100
150
200
250
Output Frequency (MHz)
Figure 8.
Copyright © 2009–2011, Texas Instruments Incorporated
15
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
TEST CONFIGURATIONS
This section describes the function of each block for the CDCM61002. Figure 9 through Figure 15 illustrate how
the device should be set up for a variety of output configurations.
LVCMOS
5 pF
Figure 9. LVCMOS Output Loading During Device Test
Phase Noise
Analyzer
LVCMOS
Figure 10. LVCMOS AC Configuration During Device Test
Oscilloscope
LVPECL
50 W
50 W
VCC - 2V
Figure 11. LVPECL DC Configuration During Device Test
Phase Noise
Analyzer
LVPECL
150 W
150 W
50 W
Figure 12. LVPECL AC Configuration During Device Test
16
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
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100 W
LVDS
Oscilloscope
Figure 13. LVDS DC Configuration During Device Test
Phase Noise
Analyzer
LVDS
50 W
Figure 14. LVDS AC Configuration During Device Test
VOH
Yx
VOD
VOL
Yx
80%
VOUTpp
20%
0V
tr
tf
Figure 15. Output Voltage and Rise/Fall Times
Copyright © 2009–2011, Texas Instruments Incorporated
17
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
FUNCTIONAL DESCRIPTION
Phase-Locked Loop (PLL)
The CDCM61002 includes an on-chip PLL with an on-chip VCO. The PLL blocks consist of a crystal input
interface, which can also accept an LVCMOS signal, a phase frequency detector (PFD), a charge pump, an
on-chip loop filter, and prescaler and feedback dividers. Completing the CDCM61002 device are the output
divider and universal output buffer.
The PLL is powered by on-chip, low-dropout (LDO) linear voltage regulators. The regulated supply network is
partitioned such that the sensitive analog supplies are powered from separate LDOs rather than the digital
supplies which use a separate LDO regulator. These LDOs provide isolation for the PLL from any noise in the
external power-supply rail. The REG_CAP1 and REG_CAP2 pins should each be connected to ground by 10-μF
capacitors to ensure stability.
Configuring the PLL
The CDCM61002 permits PLL configurations to accommodate the various input and output frequencies listed in
Table 2 and Table 3. These configurations are accomplished by setting the prescaler divider, feedback divider
and output divider. The various dividers are managed by setting the device control pins as shown in Table 4 and
Table 5.
Crystal Input Interface
Fundamental mode is the recommended oscillation mode of operation for the input crystal and parallel
resonance is the recommended type of circuit for the crystal.
A crystal load capacitance refers to all capacitances in the oscillator feedback loop. It is equal to the amount of
capacitance seen between the terminals of the crystal in the circuit. For parallel resonant mode circuits, the
correct load capacitance is necessary to ensure the oscillation of the crystal within the expected parameters.
The CDCM61002 implements an input crystal oscillator circuitry, known as the Colpitts oscillator, and requires
one pad of the crystal to interface with the XIN pin; the other pad of the crystal is tied to ground. In this crystal
interface, it is important to account for all sources of capacitance when calculating the correct value for the
discrete capacitor component, CL, for a design.
The CDCM61002 has been characterized with 10-pF parallel resonant crystals. The input crystal oscillator stage
in the CDCM61002 is designed to oscillate at the correct frequency for all parallel resonant crystals with low-pull
capability and rated with a load capacitance that is equal to the sum of the onchip load capacitance at the XIN
pin (10-pF), crystal stray capacitance, and board parasitic capacitance between the crystal and XIN pin.
The normalized frequency error of the crystal, as a result of load capacitance mismatch, can be calculated as
Equation 2:
CS
CS
Df =
f
2(CL,R + CO) 2(CL,A + CO)
(2)
Where:
CS is the motional capacitance of the crystal,
C0 is the shunt capacitance of the crystal,
CL,R is the rated load capacitance for the crystal,
CL,A is the actual load capacitance in the implemented PCB for the crystal,
Δf is the frequency error of the crystal,
and f is the rated frequency of the crystal.
The first three parameters can be obtained from the crystal vendor.
In order to minimize the frequency error of the crystal to meet application requirements, the difference between
the rated load capacitance and the actual load capacitance should be minimized and a crystal with low-pull
capability (low CS) should be used.
18
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
For example, if an application requires less than ±50 ppm frequency error and a crystal with less than ±50 ppm
frequency tolerance is picked, the characteristics are as follows: C0 = 7 pF, CS = 10 fF, and CL,R = 12 pF. In
order to meet the required frequency error, calculate CL,A using Equation 2 to be 17 pF. Subtracting CL,R from
CL,A, results in 5 pF; care must be taken during printed circuit board (PCB) layout with the crystal and the
CDCM61002 to ensure that the sum of the crystal stray capacitance and board parisitic capacitance is less than
the calculated 5 pF.
Good layout practices are fundamental to the correct operation and reliability of the oscillator. It is critical to
locate the crystal components very close to the XIN pin to minimize routing distances. Long traces in the
oscillator circuit are a very common source of problems. Do not route other signals across the oscillator circuit.
Also, make sure power and high-frequency traces are routed as far away as possible to avoid crosstalk and
noise coupling. Avoid the use of vias; if the routing becomes very complex, it is much better to use 0-Ω resistors
as bridges to go over other signals. Vias in the oscillator circuit should only be used for connections to the
ground plane. Do not share ground connections; instead, make a separate connection to ground for each
component that requires grounding. If possible, place multiple vias in parallel for each connection to the ground
plane. Especially in the Colpitts oscillator configuration, the oscillator is very sensitive to capacitance in parallel
with the crystal. Therefore, the layout must be designed to minimize stray capacitance across the crystal to less
than 5 pF total under all circumstances to ensure proper crystal oscillation. Be sure to take into account both
PCB and crystal stray capacitance.
Table 9 lists several recommended crystals and the respective manufacturer of each.
Table 9. Recommended Crystal Manufacturers
MANUFACTURER
PART NUMBER
Vectron
VXC1-1133
Fox
218-3
Saronix
FP2650002
Phase Frequency Detector (PFD)
The PFD takes inputs from the input interface and the feedback divider and produces an output that depends on
the phase and frequency differences between the two inputs. The allowable range of frequencies at the PFD
inputs is 21.875 MHz to 28.47 MHz.
Charge Pump (CP)
The charge pump is controlled by the PFD, which dictates either to pump up or down in order to charge or
discharge the integrating section of the on-chip loop filter. The integrated and filtered charge pump current is then
converted to a voltage that drives the control voltage node of the internal VCO through the on-chip loop filter. The
charge pump current is preset to 224 μA and cannot be changed.
On-Chip PLL Loop Filter
Figure 16 shows the on-chip active loop filter topology implemented in the device. This design corresponds to a
PLL bandwidth of 400 kHz for a PFD in the range of 21.875 MHz to 28.47 MHz, and a charge pump current of
224 μA.
473.5 pF
Charge Pump
Output
20 kW
15 kW
VCO Control
Figure 16. On-Chip PLL Loop Filter Topology
Copyright © 2009–2011, Texas Instruments Incorporated
19
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
Prescaler Divider and Feedback Divider
The VCO output is routed to the prescaler divider and then to the feedback divider. The prescaler divider and
feedback divider are set in tandem with each other, according to the control pin settings given in Table 4. The
allowable combinations of the two dividers ensure that the VCO frequency and the PFD frequency are within the
specified limits.
On-Chip VCO
The CDCM61002 includes an on-chip, LC oscillator-based VCO with low phase noise covering a frequency
range of 1.75 GHz to 2.05 GHz. The VCO must be calibrated to ensure proper operation over the valid device
operating conditions. This calibration requires that the PLL be set up properly to lock the PLL loop and that the
reference clock input be present. During the first device initialization after power-up, which occurs after the
Power-On-Reset is released (2.64 V or lower, over valid device operating conditions) or a device reset with the
RSTN pin, a VCO calibration sequence is initiated after 16,384 × Reference Input Clock Cycles. The VCO
calibration then takes about 20 µs over the allowable range of the reference clock input.
The VCO calibration can also be reinitiated with a pulse on the RSTN pin at any time after POR is released on
power-up; the RSTN pulse must be at least 100 ns wide
For proper device operation, the reference input must be stable at the start of VCO calibration. Since inputs from
crystals or crystal oscillators can typically take up to 1-2ms to be stable, it is recommended to establish circuitry
on the RSTN pin that ensures device initialization including VCO calibration after a delay of greater than 5ms
compared to the power up ramp, as shown in Figure 17. A possible implementation of the delay circuitry on the
RSTN pin would be a 47nF capacitor to GND, and this in tandem with the 150kΩ on-chip pull-up resistor ensures
the appropriate delay. The CE pin has an internal 150kΩ pull-up resistor and can be left unconnected or pulled to
high for proper device operation.
tCE>0
3.3 V
Vtrigger(POR)
tRST = 5 ms
RSTN
CE
VIL, RST
VIH
Figure 17. Suggested Timing Recommendations
LVCMOS INPUT INTERFACE
Alternately, the CDCM61002 can be operated with an external ac-coupled 2.5-V LVCMOS or dc-coupled 3.3-V
LVCMOS reference input applied to the XIN pin. For proper operation, the LVCMOS reference should be
available and fairly stable by the time the power supply voltages or the RSTN pin voltage on the CDCM61002
reaches 2.27 V. See the application report SCAA111, available for download at ti.com, for more details about the
LVCMOS input interface to the CDCM61002.
Output Divider
The output from the prescaler divider is also routed to the output divider. The output divider can be set with
control pins according to Table 5.
Output Buffer
Each output buffer can be set to LVPECL or LVDS or 2x LVCMOS, according to Table 6. OSC_OUT is an
LVCMOS output that can be used to monitor proper loading of the input crystal in order to achieve the necessary
crystal frequency with the least error. The OSC_OUT turns on as soon as power is available and remains on
during deviec calibration. The output buffers are disabled during VCO calibration and are enabled only after
calibration is complete.
The output buffers on the CDCM61002 can also be disabled, along with other sections of the device, using the
CE pin according to Table 7.
20
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CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
APPLICATION INFORMATION
Start-up Time Estimation
The CDCM61002 startup time can be estimated based on the parameters defined in Table 10 and graphically
shown in Figure 18.
Table 10. Start-up Time Dependencies
PARAMETER
DEFINITION
FORMULA/METHOD OF
DETERMINATION
DESCRIPTION
1
fREF
tREF
Reference clock period
The reciprocal of the applied reference
frequency in seconds.
tpul
Power-up time (low limit)
Power-supply rise time to low limit of Power
On Reset (POR) trip point
Time required for power
supply to ramp to 2.27 V
tpuh
Power-up time (high limit)
Power supply rise time to high limit of POR
trip point
Time required for power
supply to ramp to 2.64 V
trsu
Reference start-up time
After POR releases, the Colpits oscillator is
enabled. This start-up time is required for the
500 μs best-case and 800 μs
oscillator to generate the requisite signal
worst-case
levels for the delay block to be clocked by
the reference input.
tdelay
Delay time
Internal delay time generated from the
reference clock. This delay provides time for
the reference oscillator to stabilize.
tdelay= 16384 × tref
tVCO_CAL
VCO calibration time
VCO Calibration Time generated from the
reference clock. This process selects the
operating point for the VCO based on the
PLL settings.
tVCO_CAL= 550 × tref
tPLL_LOCK
PLL lock time
Based on the 400-kHz loop
Time required for PLL to lock within ±10 ppm
bandwidth, the PLL settles in
of fREF
5τ or 12.5 μs.
Power Supply (V)
Power up
Reference
Startup
Delay
VCO Calibration
tREF =
PLL Lock
2.64 V
2.27 V
tpul
trsu
Time (s)
tpuh
tVCO_CAL
tPLL_LOCK
tdelay
Figure 18. Start-up Time Dependencies
Copyright © 2009–2011, Texas Instruments Incorporated
21
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
The CDCM61002 start-up time limits, tMAX and tMIN, can be calculated as follows:
tMAX = tpuh + trsu + tdelay + tVCO_CAL + tPLL_LOCK
tMIN = tpul + trsu + tdelay + tVCO_CAL + tPLL_LOCK
Power Considerations
As a result of the different possible configurations of the CDCM61002, Table 11 is intended to provide enough
information on the estimated current consumption of the device. Unless otherwise noted, VCC = 3.3 V and TA =
+25°C.
Table 11. Estimated Block Power Consumption
BLOCK
Entire device,
core current
Output buffer
Divide circuitry
CONDITION
CURRENT CONSUMPTION
(mA)
IN-DEVICE POWER DISSIPATION
(mW)
65
214.5
Output off, no termination
resistors
LVPECL output, active mode
28
42.4
LVCMOS output pair, static
4.5
14.85
LVCMOS output pair,
transient, 'CL' load, 'f' MHz
output frequency
V × fOUT × (CL + 20 × 10–12) × 103
V2 × fOUT × (CL + 20 × 10–12) × 103
LVDS output, active mode
20
66
Divide enabled, divide = 1
5
16.5
Divide enabled, divide = 2
10
33
Divide enabled, divide = 3, 4
15
49.5
Divide enabled, divide = 6, 8
20
66
EXTERNAL
RESISTOR
POWER
DISSIPATION
(mW)
50
From Table 11, the current consumption can be calculated for any configuration. For example, the current for the
entire device with one LVPECL output in active mode can be calculated by adding up the following blocks: core
current, LVPECL output buffer current, and the divide circuitry current. The overall in-device power consumption
can also be calculated by summing the in-device power dissipated in each of these blocks.
As an example scenario, let us consider the use case of a crystal input frequency of 25 MHz and device output
frequency of 312.5 MHz in LVPECL mode. For this case, the typical overall power dissipation can be calculated
as:
3.3 V × (65 + 2 × 28 + 10) mA = 432.3 mW
Because the LVPECL output has external resistors and the power dissipated by these resistors is 50 mW, the
typical overall in-device power dissipation is:
432.3 mW – 2 × 50 mW = 332.3 mW
When the LVPECL output is active, the average voltage is approximately 1.9 V on each output as calculated
from the LVPECL VOH and VOL specifications. Therefore, the power dissipated in each emitter resistor is
approximately (1.9 V)2/150Ω = 25 mW.
When the LVCMOS output is active and drives a load capacitance, CL, the overall LVCMOS output current
consumption is the sum of a static pre-driver current and a dynamic switching current (which is a function of the
output frequency and the load capacitance).
Let us consider another use case of a crystal input frequency of 26.5625 MHz and device output frequency of
212.5 MHz in LVCMOS mode and driving a 5-pF load capacitance. For this case, the typical overall power
dissipation can be calculated as:
3.3 V × (65 + 15 + 2 × 21.4) mA = 405.24 mW
22
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CDCM61002
www.ti.com
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
Thermal Management
Power consumption of the CDCM61002 can be high enough to require attention to thermal management. For
reliability and performance reasons, the die temperature should be limited to a maximum of +125°C. That is, as
an estimate, TA (ambient temperature) plus device power consumption times θJA should not exceed +125°C.
The device package has an exposed pad that provides the primary heat removal path as well as an electrical
grounding to the printed circuit board (PCB). To maximize the removal of heat from the package, a thermal land
pattern including multiple vias to a ground plane must be incorporated on the PCB within the footprint of the
package. The exposed pad must be soldered down to ensure adequate heat conduction out of the package.
Check the mechanical data at the end of the data sheet for land and via pattern examples.
Power-Supply Filtering
PLL-based frequency synthesizers are very sensitive to noise on the power supply, which can dramatically
increase the jitter of the PLL. This characteristic is especially true for analog-based PLLs. Thus, it is essential to
reduce noise from the system power supply, especially when jitter/phase noise is very critical to applications. A
PLL would have attenuated jitter as a result of power-supply noise at frequencies beyond the PLL bandwidth
because of attenuation by the loop response.
Filter capacitors are used to eliminate the low-frequency noise from the power supply, where the bypass
capacitors provide the very low impedance path for high-frequency noise and guard the power-supply system
against the induced fluctuations. These bypass capacitors also provide instantaneous current surges as required
by the device and should have low equivalent series resistance (ESR). To properly use these bypass capacitors,
they must be placed very close to the power-supply pins and laid out with short loops to minimize inductance. It
is recommended to add as many high-frequency (for example, 0.1-μF) bypass capacitors as there are supply
pins in the package.
The CDCM61002 power-supply requirements can be grouped into two sets: the analog supply line and the
output/input supply line. The analog supply line consists of the following power-supply pins on the CDCM61002:
VCC_PLL1, VCC_PLL2, and VCC_VCO. These pins can be shorted together. The output/input supply line
consists of the VCC_OUT and the VCC_IN power-supply pins on the CDCM61002. These pins can be shorted
together. Inserting a ferrite bead between the analog supply line and the output/input supply line isolates the
high-frequency switching noises generated by the device input and outputs, preventing them from leaking into
the sensitive analog supply line. Choosing an appropriate ferrite bead with very low dc resistance is important
because it is imperative to provide adequate isolation between the sensitive analog supply line and the other
board supply lines, and to maintain a voltage at the analog power-supply pins of the CDCM61002 that is greater
than the minimum voltage required for proper operation.
Copyright © 2009–2011, Texas Instruments Incorporated
23
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
Figure 19 shows a general recommendation for decoupling the power supply.
Board/
Output/Input
Supply
Analog
Supply
Ferrite Bead
C
10 mF
C
0.1 mF (x3)
C
10 mF
C
0.1 mF (x3)
Figure 19. Recommended Power-Supply Decoupling
Output Termination
The CDCM61002 is a 3.3-V clock driver with the following output options: LVPECL, LVDS, or LVCMOS.
LVPECL Termination
The CDCM61002 is an open emitter for LVPECL outputs. Therefore, proper biasing and termination are required
to ensure correct operation of the device and to minimize signal integrity. The proper termination for LVPECL is
50 Ω to (VCC–2) V, but this dc voltage is not readily available on most PCBs. Thus, a Thevenin equivalent circuit
is worked out for the LVPECL termination in both direct-coupled (dc) and ac-coupled cases, as shown in
Figure 20 and Figure 21. It is recommended to place all resistive components close to either the driver end or the
receiver end. If the supply voltage of the driver and receiver are different, ac-coupling is required.
130 W
130 W
VCC_OUT
VCC_OUT
CDCM61002
LVPECL
82 W
82 W
Figure 20. LVPECL Output DC Termination
VBB
CDCM61002
LVPECL
150 W
150 W
50 W
50 W
Figure 21. LVPECL Output AC Termination
24
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
LVDS Termination
The proper LVDS termination for signal integrity over two 50 Ω lines is 100 Ω between the outputs on the
receiver end. Either dc-coupled termination or ac-coupled termination can be used for LVDS outputs, as shown
in Figure 22 and Figure 23. It is recommended to place all resistive components close to either the driver end or
the receiver end. If the supply voltage of the driver and the receiver are different, ac-coupling is required.
100 W
CDCM61002
LVDS
Figure 22. LVDS Output DC Termination
100 W
CDCM61002
LVDS
Figure 23. LVDS Output AC Termination
LVCMOS Termination
Series termination is a common technique used to maintain the signal integrity for LVCMOS drivers, if connected
to a receiver with a high-impedance input with a pull-up or a pulldown resistor. For series termination, a series
resistor (RS) is placed close to the driver, as shown in Figure 24. The sum of the driver impedance and RS
should be close to the transmission line impedance, which is usually 50 Ω. Because the LVCMOS driver in the
CDCM61002 has an impedance of 30 Ω, RS is recommended to be 22 Ω to maintain proper signal integrity.
RS = 22 W
CDCM61002
LVCMOS
Figure 24. LVCMOS Output Termination
Copyright © 2009–2011, Texas Instruments Incorporated
25
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
Interfacing Between LVPECL and HCSL
Because the LVPECL common-mode voltage is different from the HCSL common-mode voltage, ac-coupled
termination is used. The 150-Ω resistor ensures proper biasing of the CDCM61002 LVPECL output stage, while
the 471-Ω and 56-Ω resistor network biases the HCSL receiver input stage, as shown in Figure 25.
471 W
471 W
VCC_OUT
VCC_OUT
0W
CDCM61002
HCSL
0W
150 W
150 W
56 W
56 W
Figure 25. LVPECL to HCSL Interface
26
Copyright © 2009–2011, Texas Instruments Incorporated
CDCM61002
SCAS870F – FEBRUARY 2009 – REVISED JUNE 2011
www.ti.com
REVISION HISTORY
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision B (July, 2009) to Revision C
Page
•
Deleted references to Single-Ended and LVCMOS input throughout document ................................................................. 1
•
Deleted fIN, ΔV/ΔT, and DutyREF parameters from Electrical Characteristics ..................................................................... 4
•
Added LVCMOS Input Interface section ............................................................................................................................. 20
Changes from Revision C (February 2010) to Revision D
Page
•
Added reference to LVCMOS reference in first Features bullet ........................................................................................... 1
•
Added reference to LVCMOS input in first paragraph of Description ................................................................................... 1
•
Updated Figure 1 .................................................................................................................................................................. 2
•
Changed name of Control Pin LVCMOS Input Characteristics section in Electrical Characteristics table .......................... 4
•
Added reference to LVCMOS input in XIN parameter of Pin Functions table ...................................................................... 8
•
Changed description of Crystal Input Interface section ...................................................................................................... 18
•
Changed description of LVCMOS Input Interface section .................................................................................................. 20
Changes from Revision D (July 2010) to Revision E
Page
•
Changed Note 1 of the Pin Functions table From: Pull-up and Pull-down refer to...To:Pull-up refers to ............................. 8
•
Deleted RPULLDOWN from Table 1 ........................................................................................................................................... 8
•
Changed values in row 24.75 of Table 2 ............................................................................................................................ 11
•
Changed the text of Configuring the PLL, deleted the last sentence ................................................................................. 18
•
Changed the On-Chip VCO section .................................................................................................................................... 20
•
Changed the Output Buffer section .................................................................................................................................... 20
•
Changed the power dissipation equation From: 3.3 V × (65 + 2 × 28 + 10) mA = 429 mW To: 3.3 V × (65 + 2 × 28 +
10) mA = 432.3 mW ............................................................................................................................................................ 22
•
Changed the power dissipation equation From: 439 mW – 2 × 50 mW = 339 mW To: 432.3 mW – 2 × 50 mW =
332.3 mW ............................................................................................................................................................................ 22
•
Deleted figure "Recommended PCB Layout for CDCM61001" from the Thermal Management section. Added text
"See the mechanical data at the end of the data sheet.." .................................................................................................. 23
Changes from Revision E (March 2011) to Revision F
Page
•
Changed the On-Chip VCO section .................................................................................................................................... 20
•
Changed Figure 17 ............................................................................................................................................................. 20
•
Moved the LVCMOS INPUT INTERFACE section prior to the Output Divider section ...................................................... 20
Copyright © 2009–2011, Texas Instruments Incorporated
27
PACKAGE OPTION ADDENDUM
www.ti.com
23-Apr-2022
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
CDCM61002RHBR
ACTIVE
VQFN
RHB
32
3000
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 85
CDCM
61002
CDCM61002RHBT
ACTIVE
VQFN
RHB
32
250
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 85
CDCM
61002
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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