TI1 CDCE421ARGER Fully-integrated, wide range, low-jitter crystal oscillator clock generator Datasheet

CDCE421A
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Fully-Integrated, Wide Range, Low-Jitter
Crystal Oscillator Clock Generator
•
FEATURES
1
• Single Supply at 3.3 V for LVPECL or LVDS
Operation
• High-Performance Clock Multiplier,
Incorporating Crystal Oscillator Circuitry with
Integrated Frequency Synthesizer
• Low Output Jitter: 380 fs RMS typical
(from 10 kHz to 20 MHz)
• Low Phase Noise at High Frequency (708-MHz
LVPECL):
– Typically –109 dBc/Hz at 10 kHz and
–146dBc/Hz at 10 MHz from the carrier
• Supports Crystal or LVCMOS Input
Frequencies from 27.35 MHz to 38.33 MHz
• Output Frequency Ranges from 10.9 MHz to
766.7 MHz and from 875.2 MHz to 1175 MHz
• Low-Voltage Differential Signaling (LVDS)
Output, 100-Ω Differential Off-Chip
Termination, 10.9-MHz to 400-MHz Frequency
Range
• Differential Low-Voltage Positive Emitter
Coupled Logic (LVPECL) Outputs, 10.9-MHz to
1.175-GHz Frequency Range
2
CE
•
•
•
•
•
•
•
•
Two Fully-Integrated Voltage-Controlled
Oscillators (VCO) Support Wide Output
Frequency Range
Fully Integrated Programmable Loop Filter
Typical Power Consumption at 3.3 V:
– 274 mW in LVDS mode
– 250 mW in LVPECL mode
Chip Enable Control Pin
Simple Serial Interface Allows Programming
after Manufacturing
Integrated On-Chip Nonvolatile Memory
(EEPROM) Stores Settings Without Applying
High Voltage
Available in 4-mm × 4-mm QFN-24 Package
ESD Protection Exceeds 2 kV (HBM)
Industrial Temperature Range: –40°C to +85°C
APPLICATIONS
•
Low-Cost, High-Frequency Crystal Oscillator
Program
Output Enable/Programming Interface and EEPROM for Configuration Settings
LVPECL or LVDS
VCO 1
Output Divider
Feedback
Divider
Prescaler
Xtal
PFD/Charge Pump
Loop Filter
Crystal
Oscillator
Input
CLK
NCLK
VCO 2
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, Texas Instruments Incorporated
CDCE421A
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DESCRIPTION
The CDCE421A is a high-performance, low phase noise clock generator. It has two fully-integrated, low-noise,
LC-based voltage-controlled oscillators (VCOs) that operate in the 1.750-GHz to 2.350-GHz frequency range(1). It
also features an integrated crystal oscillator that operates in conjunction with an external AT-cut crystal to
produce a stable frequency reference for the phase-locked loop (PLL) based frequency synthesizer.
The output frequency (fOUT) is proportional to the frequency of the input crystal (fXTAL). The prescaler divider,
feedback divider, output divider, and VCO selection set the output frequency with respect to fXTAL. Table 2
provides the look-up information for a desired frequency, fOUT, and the corresponding settings for the dividers
and VCO selection. To calculate the exact crystal oscillator frequency required for the desired output, use the
formula in Equation 1.
fXTAL =
Output Divider
´ fOUT
Feedback Divider
(1)
Where:
•
•
Output divider (1) = 1, 2, 4, 8, 16, and 32
Feedback divider (2) = 12, 16, 20, and 32
In the CDCE421A, the feedback divider is set automatically with respect to the prescaler setting. The product of
the prescaler and the feedback divider should be between 60 and 64 as shown in Table 2 to maintain a stable
control loop.
Figure 1 shows a high-level block diagram of the device. The CDCE421A supports one differential LVDS clock
output or one differential LVPECL output. All device settings are programmable through a proprietary simple
serial interface (SSI).
The device operates in 3.3-V supply environment for both LVPECL and LVDS outputs and is characterized for
operation from –40°C to +85°C. The CDCE421A is available in a QFN-24 4-mm × 4-mm package.
CDCE421 Users:
The CDCE421A provides several device enhancements to the CDCE421. For a complete description of
differences between these products, refer to Appendix C: Application Information.
XIN1
XIN2
CDCE421A
Crystal
Oscillator
PFD
Charge Pump
Loop Filter
VCO1
1894
VCO2
2157
Feedback
Divider
12, 16, 20, and 32
LVPECL
Prescaler
2, 3, 4, and 5
CE
1-Pin Interface
and
Control
Program
EEPROM
LVDS
Output Divider
1, 2, 4, 8, 16, and 32
Figure 1. Functional Block Diagram
(1)
(2)
2
Output divider and feedback divider should be from the same row in Table 2.
Feedback divider is set automatically with respect to the prescaler setting in Table 2.
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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.
AVAILABLE OPTIONS (1)
TA
PACKAGED DEVICES
FEATURES
CDCE421ARGET
24-pin QFN (RGE) package, small tape and reel
CDCE421ARGER
24-pin QFN (RGE) package, tape and reel
–40°C to +85°C
(1)
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.
ABSOLUTE MAXIMUM RATINGS
Over operating free-air temperature range (unless otherwise noted). (1)
VDD
Supply voltage (2)
VI
Voltage range for all other input pins (2)
IO
Output current for LVPECL
ESD
Electrostatic discharge (HBM)
TA
Specified free-air temperature range (no airflow)
TJ
Maximum junction temperature
TSTG
Storage temperature range
(1)
(2)
CDCE421A
UNIT
–0.5 to 4.6
V
–0.5 to VCC to +0.5
V
–50
mA
2
kV
–40 to +85
°C
+125
°C
–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 voltage values are with respect to network ground terminal.
RECOMMENDED OPERATING CONDITIONS
Over operating free-air temperature range (unless otherwise noted).
MIN
NOM
MAX
VDD
Supply voltage
3.0
3.30
3.60
V
TA
Ambient temperature (no airflow, no heatsink)
–40
+85
°C
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UNIT
3
CDCE421A
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ELECTRICAL CHARACTERISTICS
Over recommended operating conditions (unless otherwise noted).
CDCE421A
PARAMETER
VDD
Supply voltage
IVDD (LVDS)
Total current
TEST CONDITIONS
MIN
TYP
MAX
UNIT
3.00
3.30
3.60
V
LVDS Mode
83
103
mA
IVDD (LVPECL) Total current
LVPECL Mode
91
110
mA
tS
fIN = 27.35 MHz, fOUT = 109.4 MHz,
Power Supply Ramp Time = 1 ms
4
ms
Start-up time
LVDS Output Mode (See Figure 2 and Figure 4)
fCLK
Output frequency
|VOD|
LVDS differential output voltage
ΔVOD
LVDS VOD magnitude change
VOS
Offset voltage
ΔVOS
VOS magnitude change
tR
Output rise time
20% to 80% of VOUT(PP)
230
tF
Output fall time
20% to 80% of VOUT(PP)
230
IOS
10.9
400
MHz
RL = 100 Ω
247
454
mV
50
mV
–40°C to +85°C
1.1
1.3
V
50
mV
Short VOUT+ to ground, VOUT = 0 V
Short-circuit output current
Short VOUT– to ground, VOUT = 0 V
Duty cycle of the output waveform
tj, RMS
45
RMS jitter
10 kHz to 20 MHz
ps
ps
30
mA
30
mA
55
%
1 ps, RMS
LVPECL Output Mode (See Figure 3 and Figure 5)
fCLK
Output frequency
10.9
1175
VOH
LVPECL high-level output voltage
VCC – 1.2
VCC – 0.81
V
VOL
LVPECL low-level output voltage
VCC – 2.17
VCC – 1.36
V
|VOD|
LVPECL differential output voltage
tR
Output rise time
20% to 80% of VOUT(PP)
230
ps
tF
Output fall time
20% to 80% of VOUT(PP)
230
ps
407
Duty cycle of the output waveform
tj, RMS
45
RMS jitter
10 kHz to 20 MHz
VIL, CMOS
Low-level CMOS input voltage
VDD = 3.3 V
VIH, CMOS
High-level CMOS input voltage
VDD = 3.3 V
IL, CMOS
Low-level CMOS input current
IH, CMOS
High-level CMOS input current
1076
55
MHz
mV
%
1 ps, RMS
LVCMOS Input
4
0.3 × VCC
V
VDD = VDD, max, VIL = 0.0 V
–200
µA
VDD = VDD, min, VIH = 3.7 V
200
µA
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0.7 × VCC
V
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CDCE421A
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DEVICE INFORMATION
NC
NC
XIN2
XIN1
NC
NC
24
23
22
21
20
19
RGE PACKAGE
QFN-24
(TOP VIEW)
CE
1
18
NC
NC
2
17
VCC
SDATA
3
16
VCC
NC
4
15
NC
NC
5
14
NC
NC
6
13
NC
7
8
9
10
11
12
OUTN
GND
GND
OUTP
NC
NC
Thermal Pad
(Bottom Side)
CDCE421A
PIN DESCRIPTIONS
Table 1. CDCE421A Pin Descriptions
TERMINAL
NAME
TERMINAL
NO.
TYPE
ESD
PROTECTION
DESCRIPTION
CE
1
I
Y
Chip enable
CE = 1: enable the device and the outputs.
CE = 0: disable all current sources; in LVDS mode, LVDSP = LVDSN = Hi-Z;
in LVPECL mode, LVPECLP = LVPECLN = Hi-Z.
GND
8, 9
GND
Y
Ground
No connect
2, 4–6,
11–15,
18–20, 23,24
OUTN
7
O
Y
High-speed negative differential LVPECL or LVDS outputs. (Outputs are
enabled by CE and selected by the EEPROM configuration registers.)
OUTP
10
O
Y
High-speed positive differential LVPECL or LVDS outputs. (Outputs are
enabled by CE and selected by the EEPROM configuration registers.)
Do not connect these pins. Leave them floating.
SDATA
3
I
Y
Programming pin using TI proprietary interface protocol
VCC
16, 17
Power
Y
3.3-V power supply
XIN1
XIN2
21
22
I
GND/NC
Y
N
In crystal input mode, connect XIN1 to one end of the crystal and XIN2 to the
other end of the crystal. In LVCMOS input single-ended driven mode, XIN1
(pin 21) acts as an input reference, and XIN2 should connect to GND or it can
be left unconnected.
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CDCE421A
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DEVICE SETUP AND CONFIGURATION
Table 2. Crystal Frequency Selection and Device Settings
DESIRED OUTPUT
FREQUENCY (MHz)
(1)
(2)
6
REQUIRED INPUT CRYSTAL
FREQUENCY (MHz)
From
To
From
To
VCO
SELECTION
OUTPUT
DIVIDER
PRESCALER
SETTING
FEEDBACK
DIVIDER (1)
1020
1175
31.875
36.719
VCO 2
1
2
32
875.2 (2)
1020
27.351
31.875
VCO 1
1
2
32
680
766.7 (2)
34
38.333
VCO 2
1
3
20
583.5
680
29.174
34
VCO 1
1
3
20
510
587.5
31.875
36.719
VCO 2
1
4
16
437.6
510
27.351
31.875
VCO 1
1
4
16
408
460
34
38.333
VCO 2
1
5
12
350.1
408
29.174
34
VCO 1
1
5
12
340
383.3
34
38.333
VCO 2
2
3
20
291.7
340
29.174
34
VCO 1
2
3
20
255
293.8
31.875
36.719
VCO 2
2
4
16
218.8
255
27.351
31.875
VCO 1
2
4
16
204
230
34
38.333
VCO 2
2
5
12
175
204
29.174
34
VCO 1
2
5
12
170
191.7
34
38.333
VCO 2
4
3
20
145.9
170
29.174
34
VCO 1
4
3
20
127.5
146.9
31.875
36.719
VCO 2
4
4
16
109.4
127.5
27.351
31.875
VCO 1
4
4
16
102
115
34
38.333
VCO 2
4
5
12
87.5
102
29.174
34
VCO 1
4
5
12
85
95.8
34
38.333
VCO 2
8
3
20
72.9
85
29.174
34
VCO 1
8
3
20
63.8
73.4
31.875
36.719
VCO 2
8
4
16
54.7
63.8
27.351
31.875
VCO 1
8
4
16
51
57.5
34
38.333
VCO 2
8
5
12
43.8
51
29.174
34
VCO 1
8
5
12
42.5
47.9
34
38.333
VCO 2
16
3
20
36.5
42.5
29.174
34
VCO 1
16
3
20
31.9
36.7
31.875
36.719
VCO 2
16
4
16
27.4
31.9
27.351
31.875
VCO 1
16
4
16
25.5
28.8
34
38.333
VCO 2
16
5
12
21.9
25.5
29.174
34
VCO 1
16
5
12
21.3
24
34
38.333
VCO 2
32
3
20
18.2
21.3
29.174
34
VCO 1
32
3
20
15.9
18.4
31.875
36.719
VCO 2
32
4
16
13.7
15.9
27.351
31.875
VCO 1
32
4
16
12.8
14.4
34
38.333
VCO 2
32
5
12
10.9
12.8
29.174
34
VCO 1
32
5
12
Feedback divider is set automatically with respect to the prescaler setting.
Discontinuity in frequency range.
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Device Setup Example
The following example illustrates the process to calculate the required AT-cut crystal frequency that is needed to
generate a desired output frequency.
Assume we need to generate an output frequency of 622.08MHz. We use Table 3 to find that the desired output
frequency lies between 583.5 and 680.0MHz.
Table 3. Crystal Frequency Selection and Device Settings (Selection)
DESIRED OUTPUT
FREQUENCY (MHz)
(1)
REQUIRED INPUT CRYSTAL
FREQUENCY (MHz)
From
To
From
To
VCO
SELECTION
OUTPUT
DIVIDER
PRESCALER
SETTING
FEEDBACK
DIVIDER (1)
680.0
766.7
34.000
38.333
VCO 2
1
3
20
583.5
680.0
29.174
34.000
VCO 1
1
3
20
510.0
587.5
31.875
36.719
VCO 2
1
4
16
Feedback divider is set automatically with respect to the prescaler setting.
This frequency value means that the device must be configured in the following way:
VCO: VCO1
Output divider: 1
Prescaler setting: 3
To determine the correct crystal frequency required to achieve 622.08 MHz with these settings, we use
Equation 2, explained earlier in this data sheet.
fXTAL =
1 ´ 622.08 = 31.154 MHz
20
(2)
Thus, the AT-cut frequency should be 31.154 MHz (that is, between 29.174 MHz and 34.000 MHz, as shown in
Table 3).
Serial Interface and Control
The CDCE421A uses a unique, TI-proprietary interface protocol that can be configured and programmed via a
single input pin to the device. The architecture enables only writing to the device from this input pin. Reading the
content of a register can be achieved by sending a read command on the input pin and monitoring the desired
output pins (LVDS or LVPECL). In cases where the output pins cannot be used to read the content, the software
that controls the interface must account for what is written to the EEPROM and when it is programmed.
Monitoring the outputs verifies the programming modes; cycling the power on the device verifies that the
EEPROM contains the proper configuration.
The CDCE421A can be configured and programmed via the SDATA input pin. For this purpose, a pulse-code
shaped programming sequence must be written to the device as described in the EEPROM Programming
section. During the EEPROM programming phase, the device requires a stable supply voltage (VDD) of 3.3 V
±300 mV for securely writing to the EEPROM cells. After each Write to WordX instruction, the written data are
latched, made effective, and offer look-ahead before the actual data are stored into the EEPROM.
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Table 4 summarizes all valid programming commands for the CDCE421A.
Table 4. CDCE421A Programming Commands
SDATA
(1)
(2)
(3)
FUNCTION
001100
Enter Programming Mode (State 1→State 2); bits must be sent in the specified order with the
specified timing. Otherwise a time-out occurs.
111011
Enter Register Readback Mode; bits must be sent in the specified order with the specified timing.
Otherwise a time-out occurs.
000 xxxx xxxx
Write to Word0 (State 2) (1) (2) (3)
100 xxxx xxxx
Write to Word1 (State 2) (1) (2) (3)
010 xxxx xxxx
Write to Word2 (State 2) (1) (2) (3)
110 xxxx xxxx
Write to Word3 (State 2) (1) (2) (3)
001 xxxx xxxx
Write to Word4 (State 2) (1) (2) (3)
101 xxxx xxxx
Write to Word5 (State 2) (1) (2) (3)
111 xxxx xxxx
State Machine Jump: All other patterns not defined as below cause Exit to Normal Mode
111 1111 0000
Jump: Enter EEPROM programming without EEPROM lock (State2 →State 3)
111 0101 0101
Jump: Enter EEPROM programming with EEPROM lock (State 2→State 4)
111 0000 0000
Jump: Exit EEPROM programming (State 3 or State 4→State 1)
Each rising edge causes a bit to be latched.
In between the bits, some longer time delays can occur, but these delays have no effect on the data.
A Write to WordX instruction is expected to be 10 bits long. After the tenth bit, the respective word is latched, and its effect can be
observed as a look-ahead function.
Outputs (LVPECL or LVDS)
The CDCE421A device has two sets of output drivers, LVPECL and LVDS, where the outputs are wire-ORed
together. Only one output can be selected at a given time; the other output goes to a high-impedance (Hi-Z)
state.
If the device is configured for LVPECL outputs, the output buffers go to Hi-Z ,and the termination resistors
determine the state of the output (LVPECLP = LVPECLN = Hi-Z) in the device disable mode (CE = L). If the
device is configured in LVDS mode, the outputs go to a Hi-Z state if the device is disabled (CE = L).
8
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State Flow
Power Up:
Read EEPROM
and configure
Write
Word0
Write
Word1
SDATA =
100 xxxx xxxx
11th Bit
Written
Write
Word2
Power-Up
Reset
Completed
11th Bit
Written
SDATA =
000 xxxx xxxx
State1: Idle
Normal
Operation
SDATA = 111011
SDATA =
111 1111 1111
SDATA =
010 xxxx xxxx
60th Clock
Applied
11th Bit
Written
State2:
Programming
Mode
State5:
Readback
Mode
SDATA = 001100
SDATA =
110 xxxx xxxx
Write
Word3
11th Bit
Written
SDATA =
001 xxxx xxxx
SDATA =
101 xxxx xxxx
Write
Word4
11th Bit
Written
SDATA =
111 0101 0101
SDATA =
111 1111 0000
11th Bit
Written
Write
Word5
(1)
SDATA =
111 0000 0000
State4:
Programming
EEPROM
Locking
SDATA =
111 0000 0000
State3:
Programming
EEPROM
No Locking
In States 2, 3, 4, and 5, the signal pin CE is disregarded and has no influence on power down.
State Flow Diagram of Single Pin Interface
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Enter Programming Mode
Figure 2 shows the timing behavior of data to be written into SDATA. The sequence shown is '001100'. If the
high period is as short as t1, this period is interpreted as '0'. If the high period is as long as t3, this period is
interpreted as a '1'. This behavior is achieved by shifting the incoming signal SDATA by time t5 into signal
SDATA_DELAYED. As Figure 2 shows, SDATA_DELAYED can be used to latch (or strobe) SDATA. The
specification for the timings t1 through t7, tR and tF are shown in Table 5.
t7
CE
t6
t1
t3
tF
tR
t4
t2
SDATA
t5
SDATA
DELAYED
0
DATA
0
1
0
1
0
Figure 2. SDATA/CE Timing
Table 5. SDATA/CE Timing Requirements (1)
PARAMETER
MIN
60
TYP
MAX
70
80
UNIT
fSDATACLK
Repeat frequency of programming
t1
Low signal: High pulse duration
0.2 t
kHz
ms
t2
Low signal: Low pulse duration during Entering Programming sequence
0.8 t
ms
Low signal: Low pulse duration during programming bits
0.8 t
ms
t3
High signal: High pulse duration
0.8 t
ms
t4
High signal: Low pulse duration during Entering Programming sequence
0.2 t
ms
High signal: Low pulse duration during programming bits
0.2 t
ms
t6
Time-out during Entering Programming Mode and Enter Readback Mode until
next bit must occur. High-pulse or low-pulse duration each must be less than this
time; otherwise, a time-out results.
16
ms
t7
EN-high time before first SDATA can be clocked in
3t
ms
tR/tF
Rise and fall time from 20% to 80% of VDD
(1)
2
ns
t = 1/fSDATACLK.
EEPROM Programming
To program the EEPROM, follow the procedure outlined in this section.
Load all the registers in RAM by writing to Word0 ... Word5. After going back to State 2, then go to State 3
(Programming EEPROM, No Locking) or State 4 (Programming EEPROM with Locking). The contents of Word0
… to Word5 are saved in the EEPROM. Wait 10ms in State 3 or State 4 when programming the EEPROM
before moving to State 2 (idle state).
NOTE:
When writing to the device for functionality testing and verification via the serial bus,
you are only accessing the RAM. The programming of the CDCE421A can only be
performed at VCC = 3.3 V and at room temperature (+25°C).
10
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Programming Cycle of Six Words and Programming Into EEPROM Example
Figure 3 shows an Enter Programming Mode sequence and how the different words can be written. The
addressing of Word0 … Word5 can be seen in bold. After that, the inverted payload for the respective word is
clocked in. In this example, this step is followed by a Jump from State 2→State 3 into Enter EEPROM
programming with EEPROM lock. In the EEPROM programming state, it is required to wait at least 10ms for
save programming to occur. The last command is a jump from State 3 back to State 1 (normal operation). Then
cycle the power and verify that the device is functioning as programmed.
Enter Programming Sequence
Word0
Payload
Word1
Payload
Word5
Payload
State Machine Jump
State 2 ® State 3
State Machine Jump
State 3 ® State 1
After eight bits, the payload data
are transferred to the RAM
and become active
Wait for at least 10 ms
before exiting the EEPROM write phase
for save operation
Figure 3. Programming Cycle of Six Words and Programming Into EEPROM
Enter Register Readback Mode
Similar to the Enter Programming Mode sequence, the Enter Register Readback Mode is written into SDATA.
After the command has been issued, the SDATA-input is reconfigured as the clock input. By applying one clock,
the EEPROM content is read into the shift registers. Then, by applying further clocks at SDATA, the EEPROM
content can be clocked out and observed at FOUT. Additionally, FOUT is reconfigured during this operation, as
can be seen in Figure 4. There are 59 bits to be clocked out. With the 61st rising clock edge, the FOUR pin is
reconfigured for normal operation.
SDATA
FOUT
1
1
1
0
1
1
Output Oscillation
Enter Readback Sequence
0
Fetch EEPROM
content with
first CLK
1
2
56
57
EEPROM content: first bit available
after first falling edge
58
Output Oscillation
60th falling edge
switches back into
normal operation
Figure 4. Register Readback Mode Timing Sequence
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Table 6 summarizes the contents and functions of the output bit-stream. Note that bit 0 is clocked out first.
Table 6. Register Readback Mode: Output Bit-Stream
OUTPUT BIT-STREAM
12
FUNCTION
Bit[0:2]
Revision identifier (MSB first)
Bit[3:8]
VCO calibration word
Bit[9]
EEPROM Status:
0 = EEPROM has never been written
1 = EEPROM has been programmed before
Bit[10]
EEPROM Lock:
0 = EEPROM can be rewritten
1 = EEPROM is locked; rewriting the EEPROM is no longer possible
Bit[11:18]
Storage value Word5 (MSB first)
Bit[19:26]
Storage value Word4 (MSB first)
Bit[27:34]
Storage value Word3 (MSB first)
Bit[35:42]
Storage value Word2 (MSB first)
Bit[43:50]
Storage value Word1 (MSB first)
Bit[51:58]
Storage value Word0 (MSB first)
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REGISTER DESCRIPTION
Table 7. Word 0
Type
Recommended
Value
Register selection
W
0
C1
Register selection
W
0
C2
Register selection
W
0
VCO select:
0 = VCO1
1 = VCO2
W
User
SELPRESC
Prescaler setting, Bit 0
W
User
SELPRESC
Prescaler setting, Bit 1
W
User
OUTSEL
Output divider select, Bit 0
W
User
OUTSEL
Output divider select, Bit1
W
User
8
OUTSEL
Output divider select, Bit 2
W
User
9
DRVSEL
Driver select:
0 =LVDS
1=PECL
W
User
10
TITEST1
Reserved
W
1
Type
Recommended
Value
Bit
Name
0
C0
1
2
3
SELVCO
4
5
6
7
Description/Function
4
Divide by value (SELPRESC 1, SELPRESC 0)
5
Divide by 5 = (00), 3 = (01), 4 = (10), and 2 = (11)
6
Output divider (OUTSEL2, OUTSEL1, OUTSEL0)
Divide by 1 = (000) , 2 = (001), 4 = (010), 8 = (011), 16 = (100), 32 = (101)
7
8
Table 8. Word 1
Bit
Name
Description/Function
0
C0
Register selection
W
1
1
C1
Register selection
W
0
2
C2
Register selection
W
0
3
LFRCSEL
Loop filter control settings, Bit 0
W
1
4
LFRCSEL
Loop filter control settings, Bit 1
W
1
5
LFRCSEL
Loop filter control settings, Bit 2
W
1
6
LFRCSEL
Loop filter control settings, Bit 3
W
1
7
LFRCSEL
Loop filter control settings, Bit 4
W
1
8
LFRCSEL
Loop filter control settings, Bit 5
W
0
9
LFRCSEL
Loop filter control settings, Bit 6
W
1
10
LFRCSEL
Loop filter control settings, Bit 7
W
0
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Table 9. Word 2
Type
Recommended
Value
Register selection
W
0
Register selection
W
1
Register selection
W
0
LFRCSEL
Loop filter control settings, Bit 8
W
1
LFRCSEL
Loop filter control settings, Bit 9
W
1
5
LFRCSEL
Loop filter control settings, Bit 10
W
0
6
LFRCSEL
Loop filter control settings, Bit 11
W
0
7
LFRCSEL
Loop filter control settings, Bit 12
W
0
8
LFRCSEL
Loop filter control settings, Bit 13
W
0
9
LFRCSEL
Loop filter control settings, Bit 14
W
0
10
LFRCSEL
Loop filter control settings, Bit 15
W
0
Type
Recommended
Value
Bit
Name
0
C0
1
C1
2
C2
3
4
Description/Function
Table 10. Word 3
Bit
Name
Description/Function
0
C0
Register selection
W
1
1
C1
Register selection
W
1
2
C2
Register selection
W
0
3
LFRCSEL
Loop filter control settings, Bit 16
W
0
4
LFRCSEL
Loop filter control settings, Bit 17
W
0
5
LFRCSEL
Loop filter control settings, Bit 18
W
0
6
ICPSEL
Charge pump current Sel, Bit 0
W
1
7
ICPSEL
Charge pump current Sel, Bit 1
W
1
8
ICPSEL
Charge pump current Sel, Bit 2
W
1
9
ICPSEL
Charge pump current Sel, Bit 3
W
1
10
TITEST2
Reserved
W
0
Type
Recommended
Value
Table 11. Word 4
14
Bit
Name
Description/Function
0
C0
Register selection
W
0
1
C1
Register selection
W
0
2
C2
Register selection
W
1
3
CALWRD
VCO calibration Word, Bit 0
W
0
4
CALWRD
VCO calibration Word, Bit 1
W
0
5
CALWRD
VCO calibration Word, Bit 2
W
0
6
CALWRD
VCO calibration Word, Bit 3
W
0
7
CALWRD
VCO calibration Word, Bit 4
W
0
8
CALWRD
VCO calibration Word, Bit 5
W
0
9
CALOVR
VCO calibration override
W
0
10
ENCAL
Enable VCO calibration
W
1
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Table 12. Word 5
Type
Recommended
Value
Register selection
W
1
Register selection
W
0
Register selectiond
W
1
TITSTCFG
TI Test Use, Bit 0
W
0
TITSTCFG
TI Test Use, Bit 1
W
0
5
TITSTCFG
TI Test Use, Bit 2
W
0
6
TITSTCFG
TI Test Use, Bit 3
W
0
7
Not used
W
0
8
Not used
W
0
9
Not used
W
0
10
Not used
W
0
Bit
Name
0
C0
1
C1
2
C2
3
4
Description/Function
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Appendix A: Test Configurations
Test setups are used to characterize the CDCE421A device in both ac- and dc-termination. Figure 5 through
Figure 8 illustrate all four setups used to terminate the clock signal driven by the device under test.
100 W
LVDS
LVDS
Figure 5. LVDS DC Termination Test Configuration
50 W
LVPECL
LVPECL
50 W
VCC - 2 V
Figure 6. LVPECL DC Termination Test Configuration
Phase Noise
Analyzer
LVDS
50 W
Figure 7. LVDS AC Termination Test Configuration
Phase Noise
Analyzer
LVPECL
150 W
150 W
150 W
Figure 8. LVPECL AC Termination Test Configuration
16
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Appendix B: Jitter Characteristics in Input Clock Mode
If the CDCE421A is being referenced by an external and cleaner LVCMOS input of 35.42 MHz and 33.33 MHz,
respectively, Figure 9 and Table 13 show the SSB phase noise plot and phase noise data of the output at 708
MHz for LVPECL from 100 Hz to 40 MHz from the carrier.
0
Phase Noise (dBc/Hz)
-20
-40
-60
-80
-100
-120
-140
-160
10
100
1k
10k
100k
1M
10M
100M
Single-Sideband Frequency (Hz)
Figure 9. SSB Phase Noise at 708-MHz LVPECL Output with LVCMOS Input of 35.42 MHz
Table 13. Phase Noise Data for LVPECL at 708 MHz with LVCMOS Input of 35.42 MHz (1)
PARAMETER
MIN
TYP
MAX
UNIT
phn100
Phase noise at 100 Hz
–95
dBc/Hz
phn1k
Phase noise at 1 kHz
–105
dBc/Hz
phn10k
Phase noise at 10 kHz
–109
dBc/Hz
phn100k
Phase noise at 100 kHz
–114
dBc/Hz
phn1M
Phase noise at 1 MHz
–126
dBc/Hz
phn10M
Phase noise at 10 MHz
–146
dBc/Hz
phn20M
Phase noise at 20 MHz
–146
dBc/Hz
JRMS
RMS jitter from 10 kHz to 20 MHz
438
fs
(1)
Phase noise specifications under following assumptions: input frequency = 35.42 MHz (VCO = 2, prescaler = 3, output divider = 1),
output frequency = 708 MHz at LVPECL.
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Figure 10 and Table 14 show the SSB phase noise plot and phase noise at 400 MHz for LVDS from 100 Hz to
40 MHz from the carrier. See Figure 7 and Figure 8 for the test configuration setup for LVPECL and LVDS ac
termination, respectively.
0
Phase Noise (dBc/Hz)
-20
-40
-60
-80
-100
-120
-140
-160
10
100
1k
10k
100k
1M
10M
100M
Single-Sideband Frequency (Hz)
Figure 10. SSB Phase Noise at 400-MHz LVDS Output with LVCMOS Input of 33.33 MHz
Table 14. Phase Noise Data for LVDS at 400 MHz with LVCMOS Input of 33.33 MHz (1)
PARAMETER
MIN
TYP
MAX
UNIT
phn100
Phase noise at 100 Hz
–99
dBc/Hz
phn1k
Phase noise at 1 kHz
–109
dBc/Hz
phn10k
Phase noise at 10 kHz
–119
dBc/Hz
phn100k
Phase noise at 100 kHz
–121
dBc/Hz
phn1M
Phase noise at 1 MHz
–130
dBc/Hz
phn10M
Phase noise at 10 MHz
–147
dBc/Hz
phn20M
Phase noise at 20 MHz
–147
dBc/Hz
JRMS
RMS jitter from 10 kHz to 20 MHz
409
fs
(1)
18
Phase noise specifications under following assumptions: input frequency = 33.33 MHz (VCO = 1, prescaler = 5, output divider = 1),
output frequency = 400 MHz at LVDS.
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Appendix C: Application Information
CDCE421 User Information
The CDCE421A includes several device enhancements to the CDCE421.
• Device Startup
The CDCE421A includes an improved device startup circuit that enables the CDCE421A to be used in
stand-alone applications (for example, configurations in which the device is not connected to a host system).
This design operates over various power-supply ramp time scenarios. For proper operation of the startup
circuit, certain register bits must be programmed as specified in Table 15.
Table 15. CDCE421 vs. CDCE421A Register Settings
REGISTER LOCATION
CDCE421A
DATA SHEET
REFERENCE
CDCE421
CDCE421A
Word 0, Bit 10
Loop filter bias select
TITEST1 (must always
be written '1')
Table 7
Word 3, Bit 10
Not used
TITEST2 (must always
be written '0')
Table 10
space
•
•
LVDS Output Buffer
The CDCE421A incorporates an improved LVDS output buffer. Therefore, the electrical characteristics of the
LVDS output buffer on the CDCE421A are different from those of the CDCE421. Refer to the Electrical
Characteristics table for the details of the CDCE421A LVDS output buffer.
Product Revision Identification
For the product revision identifier bits (bits [2:0]), the value presented by the CDCE421A is '000'. See Table 6
for more details.
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Startup Time Estimation
The startup time for the CDCE421A can be estimated based on the parameters defined in Table 16 and
illustrated in Figure 11.
Based on these parameters, the CDCE421A startup time limits tMAX and tMIN can be calculated as shown in these
equations:
tMAX = tpuh + trsu + tdelay + tVCO_CAL + tPLL_LOCK
tMIN = tpul + trsu + tdelay + tVCO_CAL + tPLL_LOCK
Table 16. Timing Definitions: Startup Time Dependencies
Parameter
Definition
tREF
Reference Clock Period
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 Startup Time
After POR releases, the Colpits oscillator is
enabled. This startup time is required for the
oscillator to generate the requisite signal
levels for the delay block to be clocked by
the reference input.
Best case: 500 µs
Worst case: 800 µs (for a crystal input)
0 s (for an LVCMOS 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
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
tVCO_CAL
VCO Calibration Time
tPLL_LOCK
PLL Lock Time
Power Supply (V)
Power up
Reference
Startup
Description
Formula/Method of Determination
The reciprocal of the applied reference
frequency (in seconds).
tREF =
1
fREF
Time required for PLL to lock within ±10 ppm Based on the 400-kHz loop bandwidth,
of fREF.
the PLL will settle in 5 τ or 12.5 µs.
Delay
VCO Calibration
PLL Lock
2.64 V
2.27 V
tpul
trsu
tpuh
Time (s)
tVCO_CAL
tPLL_LOCK
tdelay
Figure 11. Startup Time Dependencies
20
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PACKAGE OPTION ADDENDUM
www.ti.com
25-Jun-2009
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
CDCE421ARGER
ACTIVE
VQFN
RGE
24
3000 Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
CDCE421ARGET
ACTIVE
VQFN
RGE
24
250
Green (RoHS &
no Sb/Br)
CU NIPDAU
Level-2-260C-1 YEAR
CDCE431Y
ACTIVE
DIESALE
Y
0
910
Green (RoHS &
no Sb/Br)
Call TI
N / A for Pkg Type
CDCE431YS
ACTIVE
WAFER
SALE
YS
0
1
Green (RoHS &
no Sb/Br)
Call TI
N / A for Pkg Type
Lead/Ball Finish
MSL Peak Temp (3)
(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)
Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check
http://www.ti.com/productcontent for the latest availability information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and
package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS
compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame
retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material)
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder
temperature.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is
provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the
accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take
reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on
incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited
information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI
to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
14-Jul-2012
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
Pin1
(mm) Quadrant
CDCE421ARGER
VQFN
RGE
24
3000
330.0
12.4
4.25
4.25
1.15
8.0
12.0
Q2
CDCE421ARGET
VQFN
RGE
24
250
180.0
12.4
4.25
4.25
1.15
8.0
12.0
Q2
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
14-Jul-2012
*All dimensions are nominal
Device
Package Type
Package Drawing
Pins
SPQ
Length (mm)
Width (mm)
Height (mm)
CDCE421ARGER
VQFN
RGE
24
3000
367.0
367.0
35.0
CDCE421ARGET
VQFN
RGE
24
250
210.0
185.0
35.0
Pack Materials-Page 2
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