FemtoClock
®
Crystal-to-LVDS
Frequency Synthesizer
G
ENERAL
D
ESCRIPTION
The 844002 is a 2 output LVDS Synthesizer optimized to generate
Fibre Channel reference clock frequencies. Using a 26.5625MHz
18pF parallel resonant crystal, the following frequencies can be
generated based on the 2 frequency select pins (F_SEL[1:0]):
212.5MHz, 187.5MHz, 159.375MHz, 106.25MHz and 53.125MHz.
The 844002 uses IDT’s 3
rd
generation low phase noise VCO
technology and can achieve <1ps typical rms phase jitter, easily
meeting Fibre Channel jitter requirements. The 844002 is packaged
in a small 20-pin TSSOP package.
844002
DATASHEET
F
EATURES
• Two LVDS outputs
• Selectable crystal oscillator interface
or LVCMOS/LVTTL single-ended input
• Supports the following output frequencies: 212.5MHz,
187.5MHz, 159.375MHz, 106.25MHz and 53.125MHz
• VCO range: 560MHz - 680MHz
• RMS phase jitter @ 212.5MHz, using a 26.5625MHz crystal
(637kHz - 10MHz): 0.65ps (typical)
• Full 3.3V or 2.5V supply modes
• 0°C to 70°C ambient operating temperature
• Available in lead-free (RoHS 6) package
F
REQUENCY
S
ELECT
F
UNCTION
T
ABLE
Inputs
Input
Frequency
(MHz)
26.5625
26.5625
26.5625
26.5625
23.4375
F_SEL1
0
0
1
1
0
F_SEL0
0
1
0
1
0
M Divider
Value
24
24
24
24
24
N Divider
Value
3
4
6
12
3
M/N Divider
Value
8
6
4
2
8
Output
Frequency
(MHz)
212.5 (default)
159.375
106.25
53.125
187.5 (default)
P
IN
A
SSIGNMENT
844002
20-Lead TSSOP
6.5mm x 4.4mm x 0.925mm
package body
G Package
Top View
B
LOCK
D
IAGRAM
F_SEL[1:0]
nPLL_SEL
Pulldown
Pulldown
2
Q0
REF_CLK
Pulldown
1
1
26.5625MHz
XTAL_IN
OSC
XTAL_OUT
nXTAL_SEL
Pulldown
0
Phase
Detector
VCO
637.5MHz
(w/26.5625MHz
Reference)
F_SEL[1:0]
0 0 ÷3
0 1 ÷4
1 0 ÷6
1 1 ÷12
nQ0
Q1
nQ1
0
M = 24 (fixed)
MR
Pulldown
844002 REVISION B 6/9/15
1
©2015 Integrated Device Technology, Inc.
844002 DATA SHEET
T
ABLE
1. P
IN
D
ESCRIPTIONS
Number
1, 7
2, 20
3, 4
5
Name
nc
V
DDO
Q0, nQ0
MR
Unused
Power
Ouput
Input
Type
Description
No connect.
Output supply pins.
Differential output pair. LVDS interface levels.
Active HIGH Master Reset. When logic HIGH, the internal dividers are reset
causing the true outputs Qx to go low and the inverted outputs nQx
Pulldown
to go high. When logic LOW, the internal dividers and the outputs are en-
abled. LVCMOS/LVTTL interface levels.
Selects between the PLL and REF_CLK as input to the dividers. When LOW,
Pulldown selects PLL (PLL Enable). When HIGH, deselects the reference clock (PLL
Bypass). LVCMOS/LVTTL interface levels.
Analog supply pin.
Pulldown Frequency select pins. LVCMOS/LVTTL interface levels.
Core supply pins.
Parallel resonant crystal interface. XTAL_OUT is the output,
XTAL_IN is the input.
Pulldown LVCMOS/LVTTL reference clock input.
Selects between crystal or REF_CLK inputs as the the PLL Reference
Pulldown source. Selects XTAL inputs when LOW. Selects REF_CLK when HIGH.
LVCMOS/LVTTL interface levels.
No connect.
Power supply ground.
Differential output pair. LVDS interface levels.
6
8
9, 11
10
12, 13
14
15
16
17
18, 19
Pulldown
nPLL_SEL
V
DDA
F_SEL0,
F_SEL1
V
DD
XTAL_OUT,
XTAL_IN
REF_CLK
nXTAL_SEL
nc
GND
nQ1, Q1
Input
Power
Input
Power
Input
Input
Input
Unused
Power
Output
NOTE: refers to internal input resistors. See Table 2, Pin Characteristics, for typical values.
T
ABLE
2. P
IN
C
HARACTERISTICS
Symbol
C
IN
R
PULLDOWN
Parameter
Input Capacitance
Input Pulldown Resistor
Test Conditions
Minimum
Typical
4
51
Maximum
Units
pF
kΩ
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
2
REVISION B 6/9/15
844002 DATA SHEET
A
BSOLUTE
M
AXIMUM
R
ATINGS
Supply Voltage, V
DD
Inputs, V
I
Outputs, I
O
Continuous Current
Surge Current
Package Thermal Impedance,
θ
JA
Storage Temperature, T
STG
4.6V
-0.5V to V
DD
+ 0.5V
10mA
15mA
73.2°C/W (0 lfpm)
-65°C to 150°C
N OT E : S t r e s s e s b eyo n d t h o s e l i s t e d u n d e r A b s o l u t e
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 ex-
tended periods may affect product reliability.
T
ABLE
3A. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
V
DD
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
V
DD
V
DDA
V
DDO
I
DD
I
DDA
I
DDO
Parameter
Core Supply Voltage
Analog Supply Voltage
Output Supply Voltage
Power Supply Current
Analog Supply Current
Output Supply Current
Test Conditions
Minimum
3.135
V
DD
– 0.12
3.135
Typical
3.3
3.3
3.3
Maximum
3.465
V
DD
3.465
105
12
120
Units
V
V
V
mA
mA
mA
T
ABLE
3B. P
OWER
S
UPPLY
DC C
HARACTERISTICS
,
V
DD
= V
DDO
= 2.5V±5%, T
A
= 0°C
TO
70°C
Symbol
V
DD
V
DDA
V
DDO
I
DD
I
DDA
I
DDO
Parameter
Core Supply Voltage
Analog Supply Voltage
Output Supply Voltage
Power Supply Current
Analog Supply Current
Output Supply Current
Test Conditions
Minimum
2.375
V
DD
– 0.10
2.375
Typical
2.5
2.5
2.5
Maximum
2.625
V
DD
2.625
95
10
90
Units
V
V
V
mA
mA
mA
T
ABLE
3C. LVCMOS / LVTTL DC C
HARACTERISTICS
,
V
DD
= V
DDO
= 3.3V±5%
OR
2.5V±5%, T
A
= 0°C
TO
70°C
Symbol
V
IH
V
IL
I
IH
Parameter
Input High Voltage
Input Low Voltage
Input
High Current
Input
Low Current
REF_CLK, MR,
F_SEL0, F_SEL1,
nPLL_SEL, nXTAL_SEL,
REF_CLK, MR,
F_SEL0, F_SEL1,
nPLL_SEL, nXTAL_SEL,
Test Conditions
V
DD
= 3.3V
V
DD
= 2.5V
V
DD
= 3.3V
V
DD
= 2.5V
V
DD
= V
IN
= 3.465
or 2.5V
V
DD
= 3.465V or 2.5V,
V
IN
= 0V
-150
Minimum
2
1.7
-0.3
-0.3
Typical
Maximum
V
DD
+ 0.3
V
DD
+ 0.3
0.8
0.7
150
Units
V
V
V
V
µA
I
IL
µA
REVISION B 6/9/15
3
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
844002 DATA SHEET
T
ABLE
3D. LVDS DC C
HARACTERISTICS
,
V
DD
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
V
OD
Parameter
Differential Output Voltage
OD
Test Conditions
Minimum
300
1.4
Typical
450
1.525
Maximum
600
50
1.65
50
Units
mV
mV
V
mV
Δ
V
V
OS
V
OD
Magnitude Change
Offset Voltage
V
OS
Magnitude Change
Δ
V
OS
T
ABLE
3E. LVDS DC C
HARACTERISTICS
,
V
DD
= V
DDO
= 2.5V±5%, T
A
= 0°C
TO
70°C
Symbol
V
OD
Parameter
Differential Output Voltage
OD
Test Conditions
Minimum
250
1.0
Typical
400
Maximum
550
50
1.4
50
Units
mV
mV
V
mV
Δ
V
V
OS
V
OD
Magnitude Change
Offset Voltage
V
OS
Magnitude Change
Δ
V
OS
T
ABLE
4. C
RYSTAL
C
HARACTERISTICS
Parameter
Mode of Oscillation
Frequency
Equivalent Series Resistance (ESR)
Shunt Capacitance
Drive Level
NOTE: Characterized using an 18pF parallel resonant crystal.
23.33
Test Conditions
Minimum
Typical
26.5625
Maximum
28.33
50
7
1
Units
MHz
Ω
pF
mW
Fundamental
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
4
REVISION B 6/9/15
844002 DATA SHEET
T
ABLE
5A. AC C
HARACTERISTICS
,
V
DD
= V
DDO
= 3.3V±5%, T
A
= 0°C
TO
70°C
Symbol
Parameter
Test Conditions
F_SEL[1:0] = 00
f
OUT
Output Frequency
F_SEL[1:0] = 01
F_SEL[1:0] = 10
F_SEL[1:0] = 11
tsk(o)
Output Skew; NOTE 1, 2
212.5MHz, (637kHz - 10MHz)
159.375MHz, (637kHz - 10MHz)
tjit(Ø)
RMS Phase Jitter (Random);
NOTE 3
106.25MHz, (637kHz -10MHz)
53.125MHz, (637kHz - 10MHz)
187.5MHz, (637kHz - 10MHz)
t
R
/ t
F
odc
Output Rise/Fall Time
Output Duty Cycle
20% to 80%
F_SEL[1:0]
≠
÷3
250
48
0.65
0.61
0.74
0.64
0.80
500
52
55
Minimum
186.67
140
93.33
46.67
Typical
Maximum
226.66
170
113.33
56.66
15
Units
MHz
MHz
MHz
MHz
ps
ps
ps
ps
ps
ps
ps
%
%
F_SEL[1:0] = ÷3
45
NOTE 1: Defined as skew between outputs at the same supply voltages and with equal load conditions.
Measured at the differential cross points.
NOTE 2: This parameter is defined in accordance with JEDEC Standard 65.
NOTE 3: Please refer to the Phase Noise Plot.
T
ABLE
5B. AC C
HARACTERISTICS
,
V
DD
= V
DDO
= 2.5V±5%, T
A
= 0°C
TO
70°C
Symbol
Parameter
Test Conditions
F_SEL[1:0] = 00
f
OUT
Output Frequency
F_SEL[1:0] = 01
F_SEL[1:0] = 10
F_SEL[1:0] = 11
tsk(o)
Output Skew; NOTE 1, 2
212.5MHz, (637kHz - 10MHz)
159.375MHz, (637kHz - 10MHz)
tjit(Ø)
RMS Phase Jitter (Random);
NOTE 3
106.25MHz, (637kHz -10MHz)
53.125MHz, (637kHz - 10MHz)
187.5MHz, (637kHz - 10MHz)
t
R
/ t
F
odc
Output Rise/Fall Time
Output Duty Cycle
20% to 80%
F_SEL[1:0]
≠
÷3
250
48
0.65
0.61
0.74
0.64
0.80
500
52
55
Minimum
186.67
140
93.33
46.67
Typical
Maximum
226.66
170
113.33
56.66
15
Units
MHz
MHz
MHz
MHz
ps
ps
ps
ps
ps
ps
ps
%
%
F_SEL[1:0] = ÷3
45
NOTE 1: Defined as skew between outputs at the same supply voltages and with equal load conditions.
Measured at the differential cross points.
NOTE 2: This parameter is defined in accordance with JEDEC Standard 65.
NOTE 3: Please refer to the Phase Noise Plot.
REVISION B 6/9/15
5
FEMTOCLOCKS™ CRYSTAL-TO-LVDS
FREQUENCY SYNTHESIZER
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