Si53304

Si53304
1:6 L OW J I T T E R U NIVERSAL B U F F E R /L EVEL
T RANSLATOR WITH 2 : 1 I NPUT M UX A N D I NDIVIDUAL OE
Features








6 differential or 12 LVCMOS outputs 
Ultra-low additive jitter: 45 fs rms
Wide frequency range: 1 to 725 MHz 
Any-format input with pin selectable 
output formats: LVPECL, Low Power
LVPECL, LVDS, CML, HCSL,

LVCMOS
2:1 mux with hot-swappable inputs 
Glitchless input clock switching

Synchronous output enable

Individual output enable
Independent VDD and VDDO:
1.8/2.5/3.3 V
1.2/1.5 V LVCMOS output support
Excellent power supply noise
rejection (PSRR)
Selectable LVCMOS drive strength to
tailor jitter and EMI performance
Small size: 32-QFN (5x5 mm)
RoHS compliant, Pb-free
Industrial temperature range:
–40 to +85 °C
Ordering Information:
See page 28.
Applications
High-speed clock distribution
Ethernet switch/router
 Optical Transport Network (OTN)
 SONET/SDH
 PCI Express Gen 1/2/3
Storage
Telecom
 Industrial
 Servers
 Backplane clock distribution




Pin Assignments
Si53304
Q1
Q2
Q2
Q3
Q3
Q4
Q4
32
31
30
29
28
27
26
25
OE 5
OE0
1
24
SFOUTA[1]
2
23
SFOUTB[1]
SFOUTA[0]
3
22
SFOUTB[0]
Q0
4
21
Q5
Q0
5
20
Q5
GND
6
19
V DDOB
V DD
7
18
V DDOA
CLK_SEL
8
17
V REF
9
10
11
12
13
14
15
16
OE1
CLK0
OE2
OE3
CLK1
CLK1
OE4
GND
PAD
CLK0
The Si53304 is an ultra low jitter six output differential buffer with pin-selectable
output clock signal format and individual OE. The Si53304 features a 2:1 mux with
glitchless switching, making it ideal for redundant clocking applications. The
Si53304 utilizes Silicon Laboratories' advanced CMOS technology to fanout
clocks from 1 to 725 MHz with guaranteed low additive jitter, low skew, and low
propagation delay variability. The Si53304 features minimal cross-talk and
provides superior supply noise rejection, simplifying low jitter clock distribution in
noisy environments. Independent core and output bank supply pins provide
integrated level translation without the need for external circuitry.
Q1
Description
Functional Block Diagram
VDD
VREF
Vref
Generator
VDDOA
SFOUTA[1:0]
OE[2:0]
Power
Supply
Filtering
Patents pending
CLK0
BANK A
/CLK0
VDDOB
SFOUTB[1:0]
OE[5:3]
CLK1
/CLK1
CLK_SEL
Rev. 1.0 4/14
Switching
Logic
BANK B
Copyright © 2014 by Silicon Laboratories
Si53304
Si53304
TABLE O F C ONTENTS
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
2. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.1. Universal, Any-Format Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.2. Input Bias Resistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3. Input Clock Voltage Reference (VREF) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4. Universal, Any-Format Output Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.5. Glitchless Clock Input Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.6. Synchronous Output Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.7. Input Mux and Output Enable Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.8. Power Supply (VDD and VDDOX) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.9. Output Clock Termination Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
2.10. AC Timing Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.11. Typical Phase Noise Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.12. Input Mux Noise Isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.13. Power Supply Noise Rejection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
4. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.1. 5x5 mm 32-QFN Package Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
5. PCB Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
5.1. 5x5 mm 32-QFN Package Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.1. Si53304 Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.2. Top Marking Explanation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
2
Rev. 1.0
Si53304
1. Electrical Specifications
Table 1. Recommended Operating Conditions
Parameter
Ambient Operating
Temperature
Supply Voltage Range*
Output Buffer Supply
Voltage*
Symbol
Test Condition
Min
Typ
Max
Unit
–40
—
85
°C
1.71
1.8
1.89
V
2.38
2.5
2.63
V
2.97
3.3
3.63
V
LVPECL, low power LVPECL,
LVCMOS
2.38
2.5
2.63
V
2.97
3.3
3.63
V
HCSL
2.97
3.3
3.63
V
LVDS, CML, LVCMOS
1.71
1.8
1.89
V
2.38
2.5
2.63
V
2.97
3.3
3.63
V
2.38
2.5
2.63
V
2.97
3.3
3.63
V
2.97
3.3
3.63
V
TA
VDD
VDDOX
LVDS, CML
LVPECL, low power LVPECL
HCSL
*Note: Core supply VDD and output buffer supplies VDDO are independent. LVCMOS clock input is not supported for VDD =
1.8V but is supported for LVCMOS clock output for VDDOX = 1.8V. LVCMOS outputs at 1.5V and 1.2V can be
supported via a simple resistor divider network. See “2.9.1. LVCMOS Output Termination To Support 1.5V and 1.2V”
Table 2. Input Clock Specifications
(VDD=1.8 V  5%, 2.5 V  5%, or 3.3 V  10%, TA=–40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Differential Input Common
Mode Voltage
VCM
VDD = 2.5 V 5%, 3.3 V 10%
0.05
—
—
V
Differential Input Swing
(peak-to-peak)
VIN
0.2
—
2.2
V
LVCMOS Input High Voltage
VIH
VDD = 2.5 V 5%, 3.3 V 10%
VDD x 0.7
—
—
V
LVCMOS Input Low Voltage
VIL
VDD = 2.5 V 5%, 3.3 V 10%
—
—
VDD x
0.3
V
Input Capacitance
CIN
CLK0 and CLK1 pins with
respect to GND
—
5
—
pF
Rev. 1.0
3
Si53304
Table 3. DC Common Characteristics
(VDD = 1.8 V 5%, 2.5 V  5%, or 3.3 V 10%,TA = –40 to 85 °C)
Parameter
Supply Current
Output Buffer
Supply Current
(Per Clock Output)
@100 MHz (diff)
@200 MHz (CMOS)
Symbol
Test Condition
Min
Typ
Max
Unit
—
65
100
mA
LVPECL (3.3 V)
—
35
—
mA
Low Power LVPECL (3.3 V)*
—
35
—
mA
LVDS (3.3 V)
—
20
—
mA
CML (3.3 V)
—
35
—
mA
HCSL, 100 MHz, 2 pF load (3.3 V)
—
35
—
mA
CMOS (1.8 V, SFOUT = Open/0),
per output, CL = 5 pF, 200 MHz
—
5
—
mA
CMOS (2.5 V, SFOUT = Open/0),
per output, CL = 5 pF, 200 MHz
—
8
—
mA
CMOS (3.3 V, SFOUT = 0/1),
per output, CL = 5 pF, 200 MHz
—
15
—
mA
IDD
IDDOX
Input Clock Voltage
Reference
VREF
VREF pin
IREF = +/-500 A
—
VDD/2
—
V
Input High Voltage
VIH
SFOUTx,
CLK_SEL, OEx
0.8 x
VDD
—
—
V
Input Mid Voltage
VIM
SFOUTx,
3-level input pins
0.45 x
VDD
0.5 x
VDD
0.55 x
VDD
V
Input Low Voltage
VIL
SFOUTx,
CLK_SEL, OEx
—
—
0.2 x
VDD
V
Internal Pull-down
Resistor
RDOWN
CLK_SEL, SFOUTx
—
25
—
k
RUP
OEx, SFOUTx
—
25
—
k
Internal Pull-up
Resistor
*Note: Low-power LVPECL mode supports an output termination scheme that will reduce overall system power.
4
Rev. 1.0
Si53304
Table 4. Output Characteristics (LVPECL)
(VDDOX = 2.5 V ± 5%, or 3.3 V ± 10%,TA = –40 to 85 °C)
Parameter
Symbol
Output DC Common Mode
Voltage
Min
Typ
Max
Unit
VCOM
VDDOX – 1.595
—
VDDOX – 1.245
V
VSE
0.55
0.80
1.050
V
Single-Ended
Output Swing*
Test Condition
*Note: Unused outputs can be left floating. Do not short unused outputs to ground.
Table 5. Output Characteristics (Low Power LVPECL)
(VDDOX = 2.5 V ± 5%, or 3.3 V ± 10%,TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Output DC Common
Mode Voltage
VCOM
RL = 100 across Qn and Qn
VDDOX – 1.895
VSE
RL = 100 across Qn and Qn
0.25
Single-Ended
Output Swing
Typ
0.60
Max
Unit
VDDOX – 1.275
V
0.85
V
Table 6. Output Characteristics—CML
(VDDOX = 1.8 V 5%, 2.5 V  5%, or 3.3 V 10%,TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Single-Ended Output
Swing
VSE
Terminated as shown in Figure 9
(CML termination).
300
400
550
mV
Table 7. Output Characteristics—LVDS
(VDDOX = 1.8 V 5%, 2.5 V  5%, or 3.3 V 10%,TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Single-Ended Output
Swing
VSE
RL = 100 Ω across QN and QN
247
—
490
mV
Output Common
Mode Voltage
(VDDO = 2.5 V or
3.3V)
VCOM1
VDDOX = 2.38 to 2.63 V, 2.97 to
3.63 V, RL = 100 Ω across QN
and QN
1.10
1.25
1.35
V
Output Common
Mode Voltage
(VDDO = 1.8 V)
VCOM2
VDDOX = 1.71 to 1.89 V,
RL = 100 Ω across QN
and QN
0.85
0.97
1.25
V
Rev. 1.0
5
Si53304
Table 8. Output Characteristics—LVCMOS
(VDDOX = 1.8 V 5%, 2.5 V  5%, or 3.3 V 10%,TA = –40 to 85 °C)
Parameter
Symbol
Output Voltage High*
Output Voltage Low*
Test Condition
Min
Typ
Max
Unit
VOH
0.75 x VDDOX
—
—
V
VOL
—
—
0.25 x VDDOX
V
*Note: IOH and IOL per the Output Signal Format Table for specific VDDOX and SFOUTx settings.
Table 9. Output Characteristics—HCSL
(VDDOX = 3.3 V ± 10%, TA = –40 to 85 °C))
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Output Voltage High
VOH
RL = 50 Ω to GND
550
700
900
mV
Output Voltage Low
VOL
RL = 50 Ω to GND
–150
0
150
mV
Single-Ended
Output Swing
VSE
RL = 50 Ω to GND
550
700
850
mV
Crossing Voltage
VC
RL = 50 Ω to GND
250
350
550
mV
Table 10. AC Characteristics
(VDD = VDDOX = 1.8 V 5%, 2.5 V  5%, or 3.3 V 10%,TA = –40 to 85 °C)
Parameter
Frequency
Duty Cycle
Symbol
Test Condition
Min
Typ
Max
Unit
F
LVPECL, low power LVPECL, LVDS,
CML, HCSL
1
—
725
MHz
LVCMOS
1
—
200
MHz
200 MHz, 20/80%TR/TF<10% of
period (LVCMOS)
(12 mA drive)
40
50
60
%
20/80% TR/TF<10% of period
(Differential)
48
50
52
%
Required to meet prop delay and
additive jitter specifications
(20–80%)
0.75
—
—
V/ns
DC
Note: 50% input duty cycle.
Minimum Input Clock
Slew Rate
SR
Notes:
1. HCSL measurements were made with receiver termination. See Figure 9 on page 18.
2. Output to Output skew specified for outputs with an identical configuration.
3. Defined as skew between any output on different devices operating at the same supply voltage, temperature, and
equal load condition. Using the same type of inputs on each device, the outputs are measured at the differential cross
points.
4. Measured for 156.25 MHz carrier frequency. Sine-wave noise added to VDDOX (3.3 V = 100 mVPP) and noise spur
amplitude measured. See “AN491: Power Supply Rejection for Low-Jitter Clocks” for further details.
6
Rev. 1.0
Si53304
Table 10. AC Characteristics (Continued)
(VDD = VDDOX = 1.8 V 5%, 2.5 V  5%, or 3.3 V 10%,TA = –40 to 85 °C)
Parameter
Output Rise/Fall Time
Symbol
Test Condition
Min
Typ
Max
Unit
TR/TF
LVDS, 20/80%
—
—
325
ps
LVPECL, 20/80%
—
—
350
ps
HCSL , 20/80%
—
—
280
ps
CML, 20/80%
—
—
350
ps
Low-Power LVPECL, 20/80%
—
—
325
ps
LVCMOS 200 MHz, 20/80%,
2 pF load
—
—
750
ps
500
—
—
ps
LVCMOS (12mA drive with no load)
1250
2000
2750
ps
LVPECL
600
800
1000
ps
LVDS
600
800
1000
ps
F = 1 MHz
—
2500
—
ns
F = 100 MHz
—
30
—
ns
F = 725 MHz
—
5
—
ns
F = 1 MHz
—
2000
—
ns
F = 100 MHz
—
30
—
ns
F = 725 MHz
—
5
—
ns
LVCMOS (12 mA drive to no load)
—
50
120
ps
LVPECL
—
35
70
ps
LVDS
—
35
70
ps
TPS
Differential
—
—
150
ps
PSRR
10 kHz sinusoidal noise
—
–65
—
dBc
100 kHz sinusoidal noise
—
–63
—
dBc
500 kHz sinusoidal noise
—
–60
—
dBc
1 MHz sinusoidal noise
—
–55
—
dBc
1
Minimum Input Pulse
Width
Propagation Delay
Output Enable Time
Output Disable Time
Output to Output
Skew2
Part to Part Skew3
Power Supply Noise
Rejection4
TW
TPLH,
TPHL
TEN
TDIS
TSK
Notes:
1. HCSL measurements were made with receiver termination. See Figure 9 on page 18.
2. Output to Output skew specified for outputs with an identical configuration.
3. Defined as skew between any output on different devices operating at the same supply voltage, temperature, and
equal load condition. Using the same type of inputs on each device, the outputs are measured at the differential cross
points.
4. Measured for 156.25 MHz carrier frequency. Sine-wave noise added to VDDOX (3.3 V = 100 mVPP) and noise spur
amplitude measured. See “AN491: Power Supply Rejection for Low-Jitter Clocks” for further details.
Rev. 1.0
7
Si53304
Table 11. Additive Jitter, Differential Clock Input
VDD
Output
Input1,2
Freq
(MHz)
Clock Format
Amplitude
VIN
(Single-Ended,
Peak-to-Peak)
Differential
Clock Format
20%-80% Slew
Rate (V/ns)
Additive Jitter
(fs rms, 12 kHz to
20 MHz)3
Typ
Max
3.3
725
Differential
0.15
0.637
LVPECL
45
65
3.3
725
Differential
0.15
0.637
LVDS
50
65
3.3
156.25
Differential
0.5
0.458
LVPECL
160
185
3.3
156.25
Differential
0.5
0.458
LVDS
150
200
2.5
725
Differential
0.15
0.637
LVPECL
45
65
2.5
725
Differential
0.15
0.637
LVDS
50
65
2.5
156.25
Differential
0.5
0.458
LVPECL
145
185
2.5
156.25
Differential
0.5
0.458
LVDS
145
195
Notes:
1. For best additive jitter results, use the fastest slew rate possible. See “AN766: Understanding and Optimizing Clock
Buffer’s Additive Jitter Performance” for more information.
2. AC-coupled differential inputs.
3. Measured differentially using a balun at the phase noise analyzer input. See Figure 1.
8
Rev. 1.0
Si53304
Table 12. Additive Jitter, Single-Ended Clock Input
VDD
Output
Input1,2
Freq
(MHz)
Clock Format
Amplitude
VIN
(single-ended,
peak to peak)
Additive Jitter
(fs rms, 12 kHz to
20 MHz)3
SE 20%-80%
Slew Rate
(V/ns)
Clock Format
Typ
Max
3.3
200
Single-ended
1.70
1
LVCMOS4
120
160
3.3
156.25
Single-ended
2.18
1
LVPECL
160
185
3.3
156.25
Single-ended
2.18
1
LVDS
150
200
3.3
156.25
Single-ended
2.18
1
LVCMOS4
130
180
2.5
200
Single-ended
1.70
1
LVCMOS5
120
160
2.5
156.25
Single-ended
2.18
1
LVPECL
145
185
2.5
156.25
Single-ended
2.18
1
LVDS
145
195
2.5
156.25
Single-ended
2.18
1
LVCMOS5
140
180
Notes:
1. For best additive jitter results, use the fastest slew rate possible. See “AN766: Understanding and Optimizing Clock
Buffer’s Additive Jitter Performance” for more information.
2. DC-coupled single-ended inputs.
3. Measured differentially using a balun at the phase noise analyzer input. See Figure 1.
4. Drive Strength: 12 mA, 3.3 V (SFOUT = 11). LVCMOS jitter is measured single-ended.
5. Drive Strength: 9 mA, 2.5 V (SFOUT = 11). LVCMOS jitter is measured single-ended.
PSPL 5310A
CLK SYNTH
SMA103A
50
Si533xx
DUT
Balun
PSPL 5310A
CLKx
AG E5052 Phase Noise
Analyzer
50ohm
/CLKx
50
Balun
Figure 1. Differential Measurement Method Using a Balun
Rev. 1.0
9
Si53304
Table 13. Thermal Conditions
Parameter
Symbol
Test Condition
Value
Unit
Thermal Resistance,
Junction to Ambient
JA
Still air
49.6
°C/W
Thermal Resistance,
Junction to Case
JC
Still air
32.3
°C/W
Table 14. Absolute Maximum Ratings
Parameter
Symbol
Storage Temperature
Min
Typ
Max
Unit
TS
–55
—
150
C
Supply Voltage
VDD
–0.5
—
3.8
V
Input Voltage
VIN
–0.5
—
VDD+ 0.3
V
Output Voltage
VOUT
—
—
VDD+ 0.3
V
ESD Sensitivity
HBM
—
—
2000
V
ESD Sensitivity
CDM
—
—
500
V
Peak Soldering
Reflow Temperature
TPEAK
—
—
260
C
—
—
125
C
Maximum Junction
Temperature
Test Condition
HBM, 100 pF, 1.5 k
Pb-Free; Solder reflow profile
per JEDEC J-STD-020
TJ
Note: Stresses beyond those listed in this table may cause permanent damage to the device. Functional operation
specification compliance is not implied at these conditions. Exposure to maximum rating conditions for extended
periods may affect device reliability.
10
Rev. 1.0
Si53304
2. Functional Description
The Si53304 is a low jitter, low skew 1:6 differential buffer with an integrated 2:1 input mux and individual OE
control. The device has a universal input that accepts most common differential or LVCMOS input signals. A clock
select pin control is used to select the active input clock. The selected clock input is routed to two independent
banks of outputs. Each output bank features control pins to select signal format setting and LVCMOS drive
strength. In addition, each clock output has an independent OE pin for individual clock enable/disable.
2.1. Universal, Any-Format Input
The universal input stage enables simple interfacing to a wide variety of clock formats, including LVPECL, lowpower LVPECL, LVCMOS, LVDS, HCSL, and CML. Tables 15 and 16 summarize the various ac- and dc-coupling
options supported by the device. For the best high-speed performance, the use of differential formats is
recommended. For both single-ended and differential input clocks, the fastest possible slew rate is recommended
as low slew rates can increase the noise floor and degrade jitter performance. Though not required, a minimum
slew rate of 0.75 V/ns is recommended for differential formats and 1.0 V/ns for single-ended formats. See “AN766:
Understanding and Optimizing Clock Buffer’s Additive Jitter Performance” for more information.
Table 15. LVPECL, LVCMOS, and LVDS Input Clock Options
LVPECL
LVCMOS
LVDS
AC-Couple
DC-Couple
AC-Couple
DC-Couple
AC-Couple
DC-Couple
1.8 V
N/A
N/A
No
No
Yes
No
2.5/3.3 V
Yes
Yes
No
Yes
Yes
Yes
Table 16. HCSL and CML Input Clock Options
HCSL
CML
AC-Couple
DC-Couple
AC-Couple
DC-Couple
1.8 V
No
No
Yes
No
2.5/3.3 V
Yes (3.3 V)
Yes (3.3 V)
Yes
No
0.1 µF
Si533xx
CLKx
100 
/CLKx
0.1 µF
Figure 2. Differential HCSL, LVPECL, Low-Power LVPECL, LVDS, CML AC-Coupled Input
Termination
VDD
1 k
VDDO= 3.3 V or 2.5 V
VDD
Si533xx
CMOS
Driver
CLKx
50
/CLKx
Rs
VTERM = VDD/2
1 k
VREF
Figure 3. LVCMOS DC-Coupled Input Termination
Rev. 1.0
11
Si53304
VDDO
DC Coupled LVPECL Termination Scheme 1
R1
VDD
R1
VDDO = 3.3V or 2.5V
Si533xx
CLKx
50
“Standard”
LVPECL
Driver
/CLKx
50
R2
VTERM = VDDO – 2V
R1 // R2 = 50 Ohm
R2
3.3V LVPECL: R1 = 127 Ohm, R2 = 82.5 Ohm
2.5V LVPECL: R1 = 250 Ohm, R2 = 62.5 Ohm
DC Coupled LVPECL Termination Scheme 2
VDD
VDDO = 3.3V or 2.5V
Si533xx
50
“Standard”
LVPECL
Driver
CLKx
/CLKx
50
50
50
VTERM = VDDO – 2V
DC Coupled LVDS Termination
VDD
VDDO = 3.3V or 2.5V
Si533xx
CLKx
50
Standard
LVDS
Driver
/CLKx
50
100
DC Coupled HCSL Source Termination Scheme
VDDO = 3.3V
33
Si533xx
50
Standard
HCSL Driver
VDD
CLKx
/CLKx
33
50
50
50
Note: 33 Ohm series termination is optional depending on the location of the receiver.
Figure 4. Differential DC-Coupled Input Terminations
12
Rev. 1.0
Si53304
2.2. Input Bias Resistors
Internal bias resistors ensure a differential output low condition in the event that the clock inputs are not connected.
The non-inverting input is biased with a 18.75 k pull-down to GND and a 75 k pull-up to VDD. The inverting input
is biased with a 75 k pull-up to VDD.
VDD
RPU
RPU
+
RPD
CLK0 or
CLK1
–
RPU = 75 k
RPD = 18.75 k
Figure 5. Input Bias Resistors
2.3. Input Clock Voltage Reference (VREF)
The VREF pin is used to bias the input receiver when a differential input clock is terminated as a single-ended
reference clock to the device. Connect the single-ended input to either CLK0 or CLK1. Use the recommended input
termination and bias circuit as shown in Figure 3. Note that the VREF pin should be left floating when LVCMOS or
differential clocks are used.
Si533xx
CLKx
/ CLKx
VREF
100 nF
Figure 6. Using Voltage Reference with Single-Ended Input Clock
Rev. 1.0
13
Si53304
2.4. Universal, Any-Format Output Buffer
The highly flexible output drivers support a wide range of clock signal formats, including LVPECL, low power
LVPECL, LVDS, CML, HCSL, and LVCMOS. SFOUTx[1] and SFOUTx[0] are 3-level inputs that can be pinstrapped to select the Bank A and Bank B clock signal formats independently. This feature enables the device to be
used for format translation in addition to clock distribution, minimizing the number of unique buffer part numbers
required in a typical application and simplifying design reuse. For EMI reduction applications, four LVCMOS drive
strength options are available for each VDDO setting.
Table 17. Output Signal Format Selection
SFOUTX[1]
SFOUTX[0]
VDDOX = 3.3 V
VDDOX = 2.5 V
VDDOX = 1.8 V
Open*
Open*
LVPECL
LVPECL
N/A
0
0
LVDS
LVDS
LVDS
0
1
LVCMOS, 24 mA drive
LVCMOS, 18 mA drive
LVCMOS, 12 mA drive
1
0
LVCMOS, 18 mA drive
LVCMOS, 12 mA drive
LVCMOS, 9 mA drive
1
1
LVCMOS, 12 mA drive
LVCMOS, 9 mA drive
LVCMOS, 6 mA drive
Open*
0
LVCMOS, 6 mA drive
LVCMOS, 4 mA drive
LVCMOS, 2 mA drive
Open*
1
LVPECL low power
LVPECL low power
N/A
0
Open*
CML
CML
CML
1
Open*
HCSL
N/A
N/A
*Note: SFOUTx are 3-level input pins. Tie low for “0” setting. Tie high for “1” setting. When left open, the pin floats to VDD/2.
14
Rev. 1.0
Si53304
2.5. Glitchless Clock Input Switching
The input clock mux features glitchless switching between two valid input clocks. Figure 7 illustrates that switching
between input clocks does not generate runt pulses or glitches at the output.
CLK1
CLK0
CLK_SEL
Note 1
Note 2
Note 3
Qn
Notes:
1. Qn continues with CLK0 for 2-3 falling edges of CLK0.
2. Qn is disabled low for 2-3 falling edges of CLK1 .
3. Qn starts on the first rising edge after 1 + 2.
Figure 7. Glitchless Input Clock Switch
Glitchless switching between 2 input clocks that are up to 10x different in frequency is supported. When a
switchover to a new clock is made, the output will disable low after two or three clock cycles of the previouslyselected input clock. The outputs will remain low for up to three clock cycles of the newly-selected clock, after
which the outputs will start from the newly-selected input. In the case a switchover to an absent clock is made, the
output will glitchlessly stop low and wait for edges of the newly selected clock. A switchover from an absent clock to
a live clock will also be glitchless. Note that the CLK_SEL input should not be toggled faster than 1/250th the
frequency of the slower input clock.
2.6. Synchronous Output Enable
This buffer features a synchronous output enable (disable) feature. Output enable is sampled and synchronized on
the falling edge of the input clock. This feature prevents runt pulses from being generated when the outputs are
enabled or disabled.
When OE is low, Q is held low and Q is held high for differential output formats. For LVCMOS output format
options, both Q and Q are held low when OE is set low. The device outputs are enabled when the output enable pin
is unconnected. See Table 10, “AC Characteristics,” on page 6 for output enable and output disable times.
Rev. 1.0
15
Si53304
2.7. Input Mux and Output Enable Logic
Two clock inputs for applications that need to select between one of two clock sources. The CLK_SEL pin selects
the active clock input. The table below summarizes the input and output clock based on the input mux and output
enable pin settings.
Table 18. Input Mux and Output Enable Logic
CLK_SEL
CLK0
CLK1
OE1
Q2
L
L
X
H
L
L
H
X
H
H
H
X
L
H
L
H
X
H
H
H
X
X
X
L
L3
Notes:
1. Output enable active high
2. On the next negative transition of CLK0 or CLK1.
3. Single-end: Q = low, Q = low
Differential: Q = low, Q = high
2.8. Power Supply (VDD and VDDOX)
The device includes separate core (VDD) and output driver supplies (VDDOX). This feature allows the core to
operate at a lower voltage than VDDO, reducing current consumption in mixed supply applications. The core VDD
supports 3.3 V, 2.5 V, or 1.8 V. Each output bank has its own VDDOX supply, supporting 3.3 V, 2.5 V, or 1.8 V.
16
Rev. 1.0
Si53304
2.9. Output Clock Termination Options
The recommended output clock termination options are shown below.
VDDO
DC Coupled LVPECL Termination Scheme 1
R1
R1
VDDO = 3.3V or 2.5V
Si533xx
VDD = VDDO
50
Q
LVPECL
Receiver
Qn
50
R2
VTERM = VDDO – 2V
R1 // R2 = 50 Ohm
R2
3.3V LVPECL: R1 = 127 Ohm, R2 = 82.5 Ohm
2.5V LVPECL: R1 = 250 Ohm, R2 = 62.5 Ohm
DC Coupled LVPECL Termination Scheme 2
VDDO = 3.3V or 2.5V
Si533xx
VDD = VDDO
50
Q
LVPECL
Receiver
Qn
50
50
50
VTERM = VDDO – 2V
VDDO
AC Coupled LVPECL Termination Scheme 1
R1
VDDO = 3.3V or 2.5V
Si533xx
R1
0.1 uF
VDD = 3.3V or 2.5V
50
Q
LVPECL
Receiver
Qn
50
0.1 uF
Rb
R2
Rb
R2
VBIAS = VDD – 1.3V
R1 // R2 = 50 Ohm
3.3V LVPECL: R1 = 82.5 Ohm, R2 = 127 Ohm, Rb = 120 Ohm
2.5V LVPECL: R1 = 62.5 Ohm, R2 = 250 Ohm, Rb = 90 Ohm
AC Coupled LVPECL Termination Scheme 2
V DDO = 3.3V or 2.5V
Si533xx
0.1 uF
V DD = 3.3V or 2.5V
50
Q
LVPECL
Receiver
Qn
50
0.1 uF
Rb
Rb
50
50
V BIAS = V DD – 1.3 V
3.3V LVPECL: Rb = 120 Ohm
2.5V LVPECL: Rb = 90 Ohm
Figure 8. LVPECL Output Termination
Rev. 1.0
17
Si53304
DC Coupled LVDS and Low-Power LVPECL Termination
VDDO = 3.3 V or 2.5 V, or 1.8 V (LVDS only)
Si533xx
VDD
50
Q
Standard
LVDS
Receiver
Qn
50
100
AC Coupled LVDS and Low-Power LVPECL Termination
VDDO = 3.3 V or 2.5 V or 1.8 V (LVDS only)
Si533xx
0.1 uF
VDD
50
Q
Standard
LVDS
Receiver
Qn
50
0.1 uF
100
AC Coupled CML Termination
VDDO = 3.3V or 2.5V or 1.8V
Si533xx
0.1 uF
VDD
50
Q
Standard
CML
Receiver
100
Qn
50
0.1 uF
DC Coupled HCSL Receiver Termination
VDDO = 3.3V
Si533xx
VDD
50
Q
Standard
HCSL
Receiver
Qn
50
50
50
DC Coupled HCSL Source Termination
VDDO = 3.3V
Si533xx
VDD
42.2
50
Q
Qn
42.2
50
86.6
Standard
HCSL
Receiver
86.6
Figure 9. LVDS, CML, HCSL, and Low-Power LVPECL Output Termination
18
Rev. 1.0
Si53304
CMOS
Receivers
Si533xx
CMOS Driver
Zout
Rs
Zo
50
Figure 10. LVCMOS Output Termination
Table 19. Recommended LVCMOS RS Series Termination
SFOUTX[1]
SFOUTX[0]
RS (ohms)
3.3 V
2.5 V
1.8 V
0
1
33
33
33
1
0
33
33
33
1
1
33
33
0
Open
0
0
0
0
2.9.1. LVCMOS Output Termination To Support 1.5V and 1.2V
LVCMOS clock outputs are natively supported at 1.8, 2.5, and 3.3V. However, 1.2V and 1.5V LVCMOS clock
outputs can be supported via a simple resistor divider network that will translate the buffer’s 1.8V output to a lower
voltage as shown in Figure 11 below.
VDDOx= 1.8V
R1
50
R2
LVCMOS
1.5V LVCMOS: R1 = 43 ohms, R2 = 300 ohms, IOUT = 12mA
1.2V LVCMOS: R1 = 58 ohms, R2 = 150 ohms, IOUT = 12mA
R1
50
R2
Figure 11. 1.5V and 1.2V LVCMOS Low-Voltage Output Termination
Rev. 1.0
19
Si53304
2.10. AC Timing Waveforms
TPHL
TSK
VPP/2
CLK
Q
VPP/2
QN
QM
VPP/2
VPP/2
TPLH
TSK
Propagation Delay
Output-Output Skew
TF
Q
80% VPP
20% VPP
Rise/Fall Time
Figure 12. AC Waveforms
20
80% VPP
20% VPP
Q
Rev. 1.0
TR
Si53304
2.11. Typical Phase Noise Performance
Each of the following three figures shows three phase noise plots superimposed on the same diagram.
Source Jitter: Reference clock phase noise.
Total Jitter (SE): Combined source and clock buffer phase noise measured as a single-ended output to the phase
noise analyzer and integrated from 12 kHz to 20 MHz.
Total Jitter (Diff): Combined source and clock buffer phase noise measured as a differential output to the phase
noise analyzer and integrated from 12 kHz to 20 MHz. The differential measurement as shown in each figure is
made using a balun. See Figure 1 on page 9.
Note: To calculate the total RMS phase jitter when adding a buffer to your clock tree, use the root-sum-square (RSS).
The total jitter is a measure of the source plus the buffer's additive phase jitter. The additive jitter (rms) of the buffer
can then be calculated (via root-sum-square addition).
Figure 13. Source Jitter (156.25 MHz)
Rev. 1.0
21
Si53304
Figure 14. Single-Ended Total Jitter (312.5 MHz)
22
Rev. 1.0
Si53304
Figure 15. Differential Total Jitter (625 MHz)
Rev. 1.0
23
Si53304
2.12. Input Mux Noise Isolation
The buffer’s input clock mux is designed to minimize crosstalk between the CLK0 and CLK1. This improves phase
jitter performance when clocks are present at both the CLK0 and CLK1 inputs. Figure 16 below is a measurement
the input mux’s noise isolation.
LVPECL [email protected];
Selected clk is active
Unselected clk is static
Mux Isolation = 61dB
LVPECL [email protected];
Selected clk is static
Unselected clk is active
Figure 16. Input Mux Noise Isolation
2.13. Power Supply Noise Rejection
The device supports on-chip supply voltage regulation to reject noise present on the power supply, simplifying low
jitter operation in real-world environments. This feature enables robust operation alongside FPGAs, ASICs and
SoCs and may reduce board-level filtering requirements. For more information, see “AN491: Power Supply
Rejection for Low Jitter Clocks”.
24
Rev. 1.0
Q1
Q1
Q2
Q2
Q3
Q3
Q4
Q4
Si53304
32
31
30
29
28
27
26
25
OE0
1
24
OE5
SFOUTA[1]
2
23
SFOUTB[1]
SFOUTA[0]
3
22
SFOUTB[0]
Q0
4
21
Q5
Q0
5
20
Q5
GND
6
19
VDDOB
VDD
7
18
VDDOA
CLK_SEL
8
17
VREF
10
11
12
13
14
15
16
CLK0
CLK0
OE2
OE3
CLK1
CLK1
OE4
OE1
9
GND
PAD
Table 20. Pin Description
Pin
Name
Type*
Description
1
OE0
I
Output enable—Output 0
When OE = high, the Q0 is enabled.
When OE = low, Q is held low and Q is held high for differential formats.
For LVCMOS, both Q and Q are held low when OE is set low.
This pin contains an internal pull-up resistor.
2
SFOUTA[1]
I
Output signal format control pin for Bank A
Three level input control. Internally biased at VDD/2. Can be left floating
or tied to ground or VDD.
3
SFOUTA[0]
I
Output signal format control pin for Bank A
Three level input control. Internally biased at VDD/2. Can be left floating
or tied to ground or VDD.
4
Q0
O
Output clock 0 (complement)
5
Q0
O
Output clock 0
6
GND
O
Ground
7
VDD
P
Core voltage supply
Bypass with 1.0 µF capacitor and place as close to the VDD pin as possible.
Rev. 1.0
25
Si53304
Table 20. Pin Description (Continued)
26
Pin
Name
Type*
Description
8
CLK_SEL
I
Mux input select pin (LVCMOS)
Clock inputs are switched without the introduction of glitches.
When CLK_SEL is high, CLK1 is selected.
When CLK_SEL is low, CLK0 is selected.
CLK_SEL contains an internal pull-down resistor.
9
OE1
I
Output enable—Output 1
When OE = high, the Q1 is enabled.
When OE = low, Q is held low and Q is held high for differential formats.
For LVCMOS, both Q and Q are held low when OE is set low.
This pin contains an internal pull-up resistor.
10
CLK0
I
Input clock 0
11
CLK0
I
Input clock 0 (complement)
When the CLK0 is driven by a single-end input, connect CLK0 to VDD/2.
12
OE2
I
Output enable—Output 2
When OE = high, the Q2 is enabled.
When OE = low, Q is held low and Q is held high for differential formats.
For LVCMOS, both Q and Q are held low when OE is set low.
OE2 contains an internal pull-up resistor.
13
OE3
I
Output enable—Output 3
When OE = high, the Q3 is enabled.
When OE = low, Q is held low and Q is held high for differential formats.
For LVCMOS, both Q and Q are held low when OE is set low.
OE3 contains an internal pull-up resistor.
14
CLK1
I
Input clock 1
15
CLK1
I
Input clock 1 (complement)
When the CLK1 is driven by a single-end input, connect CLK1 to VDD/2.
16
OE4
I
Output enable—Output 4
When OE = high, the Q4 is enabled.
When OE = low, Q is held low and Q is held high for differential formats.
For LVCMOS, both Q and Q are held low when OE is set low.
This pin contains an internal pull-up resistor.
17
VREF
O
Input clock reference voltage used to bias CLK0 or CLK1 clock input
pins. VREF is required when a differential input clock is applied to the
device and terminated as a single-ended reference. VREF may be left
unconnected for LVCMOS or differential clock inputs. See “2.3. Input
Clock Voltage Reference (VREF)” for details.
18
VDDOA
P
Output voltage supply—Bank A (Outputs: Q0 to Q2)
Bypass with 1.0 µF capacitor and place as close to the VDDOA pin as
possible.
Rev. 1.0
Si53304
Table 20. Pin Description (Continued)
Pin
Name
Type*
Description
19
VDDOB
P
Output voltage supply—Bank B (Outputs: Q3 to Q5)
Bypass with 1.0 µF capacitor and place as close to the VDDOB pin as
possible.
20
Q5
O
Output clock 5 (complement)
21
Q5
O
Output clock 5
22
SFOUTB[0]
I
Output signal format control pin for Bank B
Three level input control. Internally biased at VDD/2. Can be left floating
or tied to ground or VDD.
23
SFOUTB[1]
I
Output signal format control pin for Bank B
Three level input control. Internally biased at VDD/2. Can be left floating
or tied to ground or VDD.
24
OE5
I
Output enable—Output 5
When OE = high, the Q5 is enabled.
When OE = low, Q is held low and Q is held high for differential formats.
For LVCMOS, both Q and Q are held low when OE is set low.
This pin contains an internal pull-up resistor.
25
Q4
O
Output clock 4 (complement)
26
Q4
O
Output clock 4
27
Q3
O
Output clock 3 (complement)
28
Q3
O
Output clock 3
29
Q2
O
Output clock 2 (complement)
30
Q2
O
Output clock 2
31
Q1
O
Output clock 1 (complement)
32
Q1
O
Output clock 1
GND
Pad
GND
GND
Ground Pad
Power supply ground and thermal relief.
*Pin types are: I = input, O = output, P = power, GND = ground.
Rev. 1.0
27
Si53304
3. Ordering Guide
Part Number
Package
PB-Free, ROHS-6
Temperature
Si53304-B-GM
32-QFN
Yes
–40 to 85 C
Si53301/4-EVB
Evaluation Board
Yes
—
Notes:
1. To buy, go to http://www.supplier-direct.com/silabs/Cart.aspx?supplierUVID=63410000&partnumber=Si53304-BGM&quantity=1&issample=0.
2. To sample, go to http://www.supplier-direct.com/silabs/Cart.aspx?supplierUVID=63410000&partnumber=Si53304-BGM&quantity=1&issample=1.
28
Rev. 1.0
Si53304
4. Package Outline
4.1. 5x5 mm 32-QFN Package Diagram
Figure 17. Si53304 5x5 mm Package Diagram
Table 21. Package Dimensions
Dimension
Min
Nom
Max
A
0.80
0.85
1.00
A1
0.00
0.02
0.05
b
0.18
0.25
0.30
c
0.20
0.25
0.30
D
D2
5.00 BSC
2.00
2.15
e
0.50 BSC
E
5.00 BSC
2.30
E2
2.00
2.15
2.30
L
0.30
0.40
0.50
aaa
0.10
bbb
0.10
ccc
0.08
ddd
0.10
Notes:
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.
3. This drawing conforms to the JEDEC Solid State Outline MO-220.
Rev. 1.0
29
Si53304
5. PCB Land Pattern
5.1. 5x5 mm 32-QFN Package Land Pattern
Figure 18. Si53304 5x5 mm Package Land Pattern
Table 22. PCB Land Pattern
Dimension
Min
Max
Dimension
Min
Max
C1
4.52
4.62
X2
2.20
2.30
C2
4.52
4.62
Y1
0.59
0.69
Y2
2.20
2.30
E
X1
0.50 BSC
0.20
0.30
Notes:
General
1. All dimensions shown are in millimeters (mm) unless otherwise noted.
2. This Land Pattern Design is based on the IPC-7351 guidelines.
Solder Mask Design
1. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask and the metal pad is to
be 60 m minimum, all the way around the pad.
Stencil Design
1. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder
paste release.
2. The stencil thickness should be 0.125 mm (5 mils).
3. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads.
4. A 2x2 array of 0.75 mm square openings on 1.15 mm pitch should be used for the center ground pad.
Card Assembly
1. A No-Clean, Type-3 solder paste is recommended.
2. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small Body Components.
30
Rev. 1.0
Si53304
6. Top Marking
6.1. Si53304 Top Marking
6.2. Top Marking Explanation
Mark Method:
Laser
Font Size:
2.0 Point (28 mils)
Center-Justified
Line 1 Marking: Device Part Number
53304
Line 2 Marking: Device Revision/Type
B-GM
Line 3 Marking: YY = Year
WW = Work Week
Corresponds to the year and work
week of the mold date.
Line 4 Marking
R = Die Rev
F = Wafer Fab
Manufacturing Code.
Circle = 0.5 mm Diameter
Lower-Left Justified
Pin 1 Identifier
A = Assembly Site
I = Internal Code
XX = Serial Lot Number
Last four characters of the Manufacturing Code from the Assembly
Purchase Order form.
Rev. 1.0
31
Si53304
DOCUMENT CHANGE LIST
Revision 0.4 to Revision 1.0
Corrected
Improved
front-page buffer block diagram.
performance specifications with more
detail.
Added additional information to clarify the use of the
voltage reference feature.
Added pin type description to Table 20, “Pin
Description,” on page 25.
Added low-voltage termination options for 1.2 V and
1.5 V LVCMOS support.
Clarified output clock bank A and bank B
assignments.
32
Rev. 1.0
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