Si5345/44/42 Data Sheet

S i5345/44/ 4 2
10 -C H A N N E L, A N Y - F R E Q U E N C Y, A N Y -O U T P U T J I T T E R
A T T E N U A T O R/ C L O C K M U L T I P L I E R
Features







Generates any combination of output 
frequencies from any input frequency 
Input frequency range:
Differential: 8 kHz to 750 MHz

LVCMOS: 8 kHz to 250 MHz
Output frequency range:

Differential: up to 712.5 MHz

LVCMOS: up to 250 MHz
Ultra-low jitter:
<100 fs typ (12 kHz–20 MHz)

Programmable jitter attenuation
bandwidth from 0.1 Hz to 4 kHz

Meets G.8262 EEC Opt 1, 2 (SyncE)

Highly configurable outputs compatible

with LVDS, LVPECL, LVCMOS, CML,
and HCSL with programmable signal

amplitude
Status monitoring (LOS, OOF, LOL)
Hitless input clock switching: automatic 

or manual

 Locks to gapped clock inputs

 Automatic free-run and holdover

modes


Optional zero delay mode
Fastlock feature for low nominal
bandwidths
Glitchless on the fly output frequency
changes
DCO mode: as low as 0.001 ppb steps.
Core voltage
VDD: 1.8 V ±5%
VDDA: 3.3 V ±5%
Independent output clock supply pins:
3.3 V, 2.5 V, or 1.8 V
Output-output skew: 20 ps typ
Serial interface: I2C or SPI
In-circuit programmable with
non-volatile OTP memory
ClockBuilder ProTM software simplifies
device configuration
Si5345: 4 input, 10 output, 64 QFN
Si5344: 4 input, 4 output, 44 QFN
Si5342: 4 input, 2 output, 44 QFN
Temperature range: –40 to +85 °C
Pb-free, RoHS-6 compliant
Ordering Information:
See section 8
Functional Block Diagram
Device Selector Guide
Grade
Max Output Frequency
Si534fA
712.5 MHz
Frequency Synthesis Modes
Integer+Fractional
Si534fB
350 MHz
Integer+Fractional
Si534fC
712.5 MHz
Integer
Si534fD
350 MHz
Integer
Applications



OTN Muxponders and Transponders
10/40/100G networking line cards
GbE/10GbE/100GbE Synchronous
Ethernet (ITU-T G.8262)





Carrier Ethernet switches
SONET/SDH Line Cards
Broadcast video
Test and measurement
ITU-T G.8262 (SyncE) Compliant
Description
These jitter attenuating clock multipliers combine fourth-generation DSPLL and
MultiSynth™ technologies to enable any-frequency clock generation and jitter
attenuation for applications requiring the highest level of jitter performance. These
devices are programmable via a serial interface with in-circuit programmable nonvolatile memory (NVM) so they always power up with a known frequency configuration.
They support free-run, synchronous, and holdover modes of operation, and offer both
automatic and manual input clock switching. The loop filter is fully integrated on-chip,
eliminating the risk of noise coupling associated with discrete solutions. Further, the
jitter attenuation bandwidth is digitally programmable, providing jitter performance
optimization at the application level. Programming the Si5345/44/42 is easy with Silicon
Labs’ ClockBuilder Pro software. Factory preprogrammed devices are also available.
Rev. 1.0 7/15
Copyright © 2015 by Silicon Laboratories
Si5345/44/42
Si5 345/44/ 42
TA B L E O F C O N T E N T S
1. Typical Application Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
2. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
3. Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
4. Detailed Block Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
5. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
5.1. Frequency Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
5.2. DSPLL Loop Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
5.3. Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
5.4. External Reference (XA/XB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
5.5. Digitally Controlled Oscillator (DCO) Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
5.6. Inputs (IN0, IN1, IN2, IN3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
5.7. Fault Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
5.8. Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
5.9. Power Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
5.10. In-Circuit Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
5.11. Serial Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
5.12. Custom Factory Preprogrammed Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
5.13. Enabling Features and/or Configuration Settings Unavailable in
ClockBuilder Pro for Factory Preprogrammed Devices . . . . . . . . . . . . . . . . . . . . . .43
6. Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
6.1. Addressing Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
6.2. High-Level Register Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
7. Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
8. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54
8.1. Ordering Part Number Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
9. Package Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
9.1. Si5345 9x9 mm 64-QFN Package Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
9.2. Si5344 and Si5342 7x7 mm 44-QFN Package Diagram . . . . . . . . . . . . . . . . . . . . . .57
10. PCB Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
11. Top Marking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
12. Device Errata . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Contact Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62
2
Rev. 1.0
Si5 3 4 5 /44/42
1. Typical Application Schematic
Figure 1. 10G Ethernet Data Center Switch and Compute Blade Schematic
Rev. 1.0
3
Si5 345/44/ 42
2. Electrical Specifications
Table 1. Recommended Operating Conditions*
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%,TA = –40 to 85 °C)
Parameter
Symbol
Min
Typ
Max
Unit
Ambient Temperature
TA
–40
25
85
°C
Junction Temperature
TJMAX
—
—
125
°C
Core Supply Voltage
VDD
1.71
1.80
1.89
V
VDDA
3.14
3.30
3.47
V
VDDO
3.14
3.30
3.47
V
2.38
2.50
2.62
V
1.71
1.80
1.89
V
3.14
3.30
3.47
V
1.71
1.80
1.89
V
Clock Output Driver Supply Voltage
Status Pin Supply Voltage
VDDS
*Note: All minimum and maximum specifications are guaranteed and apply across the recommended operating conditions.
Typical values apply at nominal supply voltages and an operating temperature of 25 °C unless otherwise noted.
4
Rev. 1.0
Si5 3 4 5 /44/42
Table 2. DC Characteristics
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, VDDO = 1.8 V ±5%, 2.5 V ±5%, or 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Core Supply Current
Symbol
Test Condition
Min
Typ
Max
Unit
IDD
Si5345
—
125
185
mA
Si5344
—
105
155
mA
Si5342
—
105
155
mA
Si5345
—
120
125
mA
Si5344
—
115
120
mA
Si5342
—
115
120
mA
LVPECL Output4
@ 156.25 MHz
—
21
25
mA
LVDS Output4
@ 156.25 MHz
—
15
18
mA
3.3 V LVCMOS5 output
@ 156.25 MHz
—
21
25
mA
2.5 V LVCMOS5 output
@ 156.25 MHz
—
16
18
mA
1.8 V LVCMOS5 output
@ 156.25 MHz
—
12
13
mA
IDDA
Output Buffer Supply Current
Total Power Dissipation
IDDOx
Pd
Si5345
Notes 1, 6
—
880
1040
mW
Si5344
Notes 2, 6
—
720
850
mW
Si5342
Notes 3, 6
—
715
840
mW
Notes:
1. Si5345 test configuration: 10x 3.3 V LVDS outputs enabled @156.25 MHz. Excludes power in termination resistors.
2. Si5344 test configuration: 4x 3.3 V LVDS outputs enabled @ 156.25 MHz. Excludes power in termination resistors.
3. Si5342 test configuration: 2x 3.3 V LVDS outputs enabled @ 156.25 MHz. Excludes power in termination resistors.
4. Differential outputs terminated into an AC coupled 100  load.
5. LVCMOS outputs measured into a 6 inch 50  PCB trace with 5 pF load. Measurements were made in CMOS3 mode.
6. Detailed power consumption for any configuration can be estimated using ClockBuilder Pro when an evaluation board
(EVB) is not available. All EVBs support detailed current measurements for any configuration.
Rev. 1.0
5
Si5 345/44/ 42
Table 3. Input Specifications
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Standard Differential or Single-Ended - AC Coupled (IN0/IN0, IN1/IN1, IN2/IN2, IN3/IN3, FB_IN/FB_IN)
Input Frequency Range
Differential
0.008
—
750
MHz
Single-ended/LVCMOS
0.008
—
250
MHz
Differential AC Coupled
fin < 250 MHz
100
—
1800
mVpp_se
Differential AC Coupled
250 MHz < fin < 750 MHz
225
—
1800
mVpp_se
Single-Ended AC Coupled
fin < 250 MHz
100
—
3600
mVpp_se
fIN_DIFF
Voltage Swing1
VIN
Slew Rate2, 3
SR
400
—
—
V/μs
Duty Cycle
DC
40
—
60
%
Capacitance
CIN
—
2
—
pF
fIN_PULSED_CMOS4
0.008
—
250
MHz
VIL
–0.2
—
0.33
V
VIH
0.49
—
—
V
Slew Rate2, 3
SR
400
—
—
V/μs
Minimum Pulse Width
PW
1.6
—
—
ns
Input Resistance
RIN
—
8
—
k
Pulsed CMOS - DC Coupled (IN0, IN1, IN2, IN3)
Input Frequency
Input Voltage4
Pulse Input
REFCLK (applied to XA/XB)
Notes:
1. Voltage swing is specified as single-ended mVpp.
2. Imposed for jitter performance.
3. Rise and fall times can be estimated using the following simplified equation: tr/tf80-20 = ((0.8 – 0.2) x VIN_Vpp_se) / SR
4. This mode is intended primarily for single-ended LVCMOS input clocks < 1 MHz that must be dc-coupled because they
have a duty cycle significantly less than 50%. A typical application example is a low-frequency video frame sync pulse.
Since the input thresholds (VIL, VIH) of this buffer are non-standard (0.33 and 0.49 V, respectively) refer to the input
attenuator circuit for dc-coupled pulsed LVCMOS in the Family Reference Manual at: www.silabs.com/
Support%20Documents/TechnicalDocs/Si5345-44-42-RM.pdf. Otherwise, for standard LVCMOS input clocks, use the
Standard Differential or Single-Ended ac-coupled input mode.
6
Rev. 1.0
Si5 3 4 5 /44/42
Table 3. Input Specifications (Continued)
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
REFCLK Frequency
Symbol
Test Condition
Min
Typ
Max
Unit
fIN_REF
Frequency range for best
output jitter performance
48
—
54
MHz
TCXO frequency for
SyncE
applications. Jitter performance may be reduced
—
40
—
MHz
—
2000
mVpp_se
2500
mVpp_diff
Input Single-ended Voltage Swing
VIN_SE
365
Input Differential Voltage
Swing
VIN_DIFF
365
Slew rate2, 3
SR
400
—
—
V/μs
Input Duty Cycle
DC
40
—
60
%
Notes:
1. Voltage swing is specified as single-ended mVpp.
2. Imposed for jitter performance.
3. Rise and fall times can be estimated using the following simplified equation: tr/tf80-20 = ((0.8 – 0.2) x VIN_Vpp_se) / SR
4. This mode is intended primarily for single-ended LVCMOS input clocks < 1 MHz that must be dc-coupled because they
have a duty cycle significantly less than 50%. A typical application example is a low-frequency video frame sync pulse.
Since the input thresholds (VIL, VIH) of this buffer are non-standard (0.33 and 0.49 V, respectively) refer to the input
attenuator circuit for dc-coupled pulsed LVCMOS in the Family Reference Manual at: www.silabs.com/
Support%20Documents/TechnicalDocs/Si5345-44-42-RM.pdf. Otherwise, for standard LVCMOS input clocks, use the
Standard Differential or Single-Ended ac-coupled input mode.
Rev. 1.0
7
Si5 345/44/ 42
Table 4. Control Input Pin Specifications
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, VDDS = 3.3 V ±5%, 1.8 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Si5345 Control Input Pins (I2C_SEL, IN_SEL[1:0], RST, OE, A1, SCLK, A0/CS, FINC, FDEC, SDA/SDIO)
VIL
—
—
0.3 x VDDIO*
V
VIH
0.7 x VDDIO*
—
—
V
Input Capacitance
CIN
—
2
—
pF
Input Resistance
RIN
—
20
—
k
Minimum Pulse Width
PW
RST, FINC and
FDEC
50
—
—
ns
Update Rate
TUR
FINC and FDEC
1
—
—
μs
Input Voltage
Si5344/42 Control Input Pins (I2C_SEL, IN_SEL[1:0], RST, OE, A1, SCLK, A0/CS, SDA/SDIO)
VIL
—
—
0.3 x VDDIO*
V
VIH
0.7 x VDDIO*
—
—
V
Input Capacitance
CIN
—
2
—
pF
Input Resistance
RIN
—
20
—
k
Minimum Pulse Width
PW
50
—
—
ns
Input Voltage
RST
*Note: VDDIO is determined by the IO_VDD_SEL bit. It is selectable as VDDA or VDD. See the Si5345/44/42 Family Reference
Manual for more details on the proper register settings.
8
Rev. 1.0
Si5 3 4 5 /44/42
Table 5. Differential Clock Output Specifications
(VDD = 1.8 V ±5%, VDDA = 3.3V ±5%, VDDO = 1.8 V ±5%, 2.5 V ±5%, or 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Output Frequency
fOUT
Duty Cycle
DC
Output-Output Skew
Test Condition
TSK
Min
Typ
Max
Unit
0.0001
—
712.5
MHz
fOUT < 400 MHz
48
—
52
%
400 MHz < fOUT < 712.5 MHz
45
—
55
%
Outputs on same Multisynth
(Normal Mode)
—
20
50
ps
Outputs on same Multisynth
(Low-Power Mode)
—
20
100
ps
—
0
100
ps
OUT-OUT Skew
TSK_OUT Measured from the positive to negative
output pins
Output Voltage Swing1
Normal Mode
VOUT
VDDO = 3.3 V or
2.5 V or 1.8 V
LVDS
350
470
550
mVpp_se
VDDO = 3.3 V or 2.5 V
LVPECL
660
810
1000
mVpp_se
VDDO = 3.3 V or
2.5 V or 1.8 V
LVDS
300
420
530
mVpp_se
VDDO = 3.3 V or 2.5 V
LVPECL
620
820
1060
mVpp_se
Low-Power Mode
VOUT
Note:
1. For normal and low-power modes, the amplitude and common-mode settings are programmable through register
settings and can be stored in NVM. Each output driver can be programmed independently. The typical normal mode (or
low-power mode) LVDS maximum is 100 mV (or 80 mV) higher than the TIA/EIA-644 maximum. Also note that the
output voltage swing specifications are given in peak-to-peak single-ended swing.
2. Not all combinations of voltage swing and common mode voltages settings are possible. See the Si5345/44/42 Family
Reference Manual for details.
3. Driver output impedance depends on selected output mode (Normal, Low-Power).
4. Measured for 156.25 MHz carrier frequency. Sinewave noise added to VDDO
(1.8 V = 50 mVpp, 2.5 V/3.3 V = 100 mVpp) and noise spur amplitude measured.
5. Measured across two adjacent outputs, both in LVDS mode, with the victim running at 155.52 MHz and the aggressor
at 156.25 MHz. Refer to “AN862: Optimizing Si534x Jitter Performance in Next Generation Internet Infrastructure
Systems” for guidance on crosstalk optimization. Note that all active outputs must be terminated when measuring
crosstalk.
Rev. 1.0
9
Si5 345/44/ 42
Table 5. Differential Clock Output Specifications (Continued)
(VDD = 1.8 V ±5%, VDDA = 3.3V ±5%, VDDO = 1.8 V ±5%, 2.5 V ±5%, or 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Common Mode Voltage1,2
(100 Ω load line-to-line)
Rise and Fall Times
(20% to 80%)
Differential Output
Impedance3
Symbol
Test Condition
Min
Typ
Max
Unit
LVDS
1.10
1.25
1.35
V
LVPECL
1.90
2.05
2.15
V
VDDO = 2.5 V
LVPECL
LVDS
1.15
1.25
1.35
V
VDDO = 1.8 V
Sub-LVDS
0.87
0.93
1.0
V
Normal Mode
—
170
240
ps
Low-Power Mode
—
300
430
Normal Mode
—
100
—

Low-Power Mode
—
650
—

Normal Mode or Low-Power Mode
VCM
tR/tF
ZO
VDDO = 3.3 V
Note:
1. For normal and low-power modes, the amplitude and common-mode settings are programmable through register
settings and can be stored in NVM. Each output driver can be programmed independently. The typical normal mode (or
low-power mode) LVDS maximum is 100 mV (or 80 mV) higher than the TIA/EIA-644 maximum. Also note that the
output voltage swing specifications are given in peak-to-peak single-ended swing.
2. Not all combinations of voltage swing and common mode voltages settings are possible. See the Si5345/44/42 Family
Reference Manual for details.
3. Driver output impedance depends on selected output mode (Normal, Low-Power).
4. Measured for 156.25 MHz carrier frequency. Sinewave noise added to VDDO
(1.8 V = 50 mVpp, 2.5 V/3.3 V = 100 mVpp) and noise spur amplitude measured.
5. Measured across two adjacent outputs, both in LVDS mode, with the victim running at 155.52 MHz and the aggressor
at 156.25 MHz. Refer to “AN862: Optimizing Si534x Jitter Performance in Next Generation Internet Infrastructure
Systems” for guidance on crosstalk optimization. Note that all active outputs must be terminated when measuring
crosstalk.
10
Rev. 1.0
Si5 3 4 5 /44/42
Table 5. Differential Clock Output Specifications (Continued)
(VDD = 1.8 V ±5%, VDDA = 3.3V ±5%, VDDO = 1.8 V ±5%, 2.5 V ±5%, or 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Power Supply Noise
Rejection4
Symbol
PSRR
Test Condition
Min
Typ
Max
Unit
10 kHz sinusoidal noise
—
–93
—
dBc
100 kHz sinusoidal noise
—
–93
—
500 kHz sinusoidal noise
—
–84
—
1 MHz sinusoidal noise
—
–79
—
10 kHz sinusoidal noise
—
–98
—
100 kHz sinusoidal noise
—
–95
—
500 kHz sinusoidal noise
—
–84
—
1 MHz sinusoidal noise
—
–76
—
Si5345
Measured spur from adjacent output5
—
–75
—
dBc
Si5342/44
Measured spur from adjacent output5
—
–85
—
dBc
Normal Mode
Low Power Mode
Output-output Crosstalk
XTALK
dBc
Note:
1. For normal and low-power modes, the amplitude and common-mode settings are programmable through register
settings and can be stored in NVM. Each output driver can be programmed independently. The typical normal mode (or
low-power mode) LVDS maximum is 100 mV (or 80 mV) higher than the TIA/EIA-644 maximum. Also note that the
output voltage swing specifications are given in peak-to-peak single-ended swing.
2. Not all combinations of voltage swing and common mode voltages settings are possible. See the Si5345/44/42 Family
Reference Manual for details.
3. Driver output impedance depends on selected output mode (Normal, Low-Power).
4. Measured for 156.25 MHz carrier frequency. Sinewave noise added to VDDO
(1.8 V = 50 mVpp, 2.5 V/3.3 V = 100 mVpp) and noise spur amplitude measured.
5. Measured across two adjacent outputs, both in LVDS mode, with the victim running at 155.52 MHz and the aggressor
at 156.25 MHz. Refer to “AN862: Optimizing Si534x Jitter Performance in Next Generation Internet Infrastructure
Systems” for guidance on crosstalk optimization. Note that all active outputs must be terminated when measuring
crosstalk.
Rev. 1.0
11
Si5 345/44/ 42
Table 6. LVCMOS Clock Output Specifications
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, VDDO = 1.8 V ±5%, 2.5 V ±5%, or 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Output Frequency
fOUT
Duty Cycle
DC
Output-to-Output Skew
TSK
Output Voltage High1, 2, 3
VOH
Test Condition
Min
Typ
Max
Unit
0.0001
—
250
MHz
fOUT <100 MHz
47
—
53
%
100 MHz < fOUT < 250 MHz
44
—
55
—
—
100
ps
VDDO x
0.85
—
—
V
—
—
—
—
—
—
—
—
—
—
—
—
—
—
VDDO = 3.3 V
OUTx_CMOS_DRV = 1
IOH = –10 mA
OUTx_CMOS_DRV = 2
IOH = –12 mA
OUTx_CMOS_DRV = 3
IOH = –17 mA
VDDO = 2.5 V
OUTx_CMOS_DRV = 1
IOH = –6 mA
OUTx_CMOS_DRV = 2
IOH = –8 mA
OUTx_CMOS_DRV = 3
IOH = –11 mA
VDDO x
0.85
V
VDDO = 1.8 V
OUTx_CMOS_DRV = 2
IOH = –4 mA
OUTx_CMOS_DRV = 3
IOH = –5 mA
VDDO x
0.85
V
Notes:
1. Driver strength is a register programmable setting and stored in NVM. Options are OUTx_CMOS_DRV = 1, 2, 3. Refer
to the Si5345/44/42 Family Reference Manual for more details on register settings.
2. IOL/IOH is measured at VOL/VOH as shown in the dc test configuration.
3. A series termination resistor (Rs) is recommended to help match the source impedance to a 50  PCB trace. A 5 pF
capacitive load is assumed. The LVCMOS outputs were set to OUTx_CMOS_DRV = 3.
12
Rev. 1.0
Si5 3 4 5 /44/42
Table 6. LVCMOS Clock Output Specifications (Continued)
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, VDDO = 1.8 V ±5%, 2.5 V ±5%, or 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Output Voltage Low1, 2, 3
VOL
Test Condition
Min
Typ
Max
Unit
VDDO
x 0.15
V
VDDO
x 0.15
V
VDDO
x 0.15
V
VDDO = 3.3 V
OUTx_CMOS_DRV=1
IOL = 10 mA
—
—
OUTx_CMOS_DRV=2
IOL = 12 mA
—
—
OUTx_CMOS_DRV=3
IOL = 17 mA
—
—
VDDO = 2.5 V
OUTx_CMOS_DRV=1
IOL = 6 mA
—
—
OUTx_CMOS_DRV=2
IOL = 8 mA
—
—
OUTx_CMOS_DRV=3
IOL = 11 mA
—
—
VDDO = 1.8 V
LVCMOS Rise and Fall
Times3
(20% to 80%)
tr/tf
OUTx_CMOS_DRV=2
IOL = 4 mA
—
—
OUTx_CMOS_DRV=3
IOL = 5 mA
—
—
VDDO = 3.3V
—
420
550
ps
VDDO = 2.5 V
—
475
625
ps
VDDO = 1.8 V
—
525
705
ps
Notes:
1. Driver strength is a register programmable setting and stored in NVM. Options are OUTx_CMOS_DRV = 1, 2, 3. Refer
to the Si5345/44/42 Family Reference Manual for more details on register settings.
2. IOL/IOH is measured at VOL/VOH as shown in the dc test configuration.
3. A series termination resistor (Rs) is recommended to help match the source impedance to a 50  PCB trace. A 5 pF
capacitive load is assumed. The LVCMOS outputs were set to OUTx_CMOS_DRV = 3.
Rev. 1.0
13
Si5 345/44/ 42
Table 7. Output Status Pin Specifications
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, VDDS = 3.3 V ±5%, 1.8 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Si5345 Status Output Pins (LOL, INTR, SDA/SDIO1, SDO)
Output Voltage
VOH
IOH = –2 mA
VDDIO x 0.75
—
—
V
VOL
IOL = 2 mA
—
—
VDDIO2 x 0.15
V
Si5344 Status Output Pins (LOL, INTR, SDA/SDIO1, SDO)
Output Voltage
VOH
IOH = –2 mA
VDDIO* x 0.75
—
—
V
VOL
IOL = 2 mA
—
—
VDDIO2 x 0.15
V
Si5342 Status Output Pins (LOL, LOS0, LOS1, LOS2, LOS3, LOS_XAXB, INTR, SDA/SDIO1, SDO)
Output Voltage
VOH
IOH = –2 mA
VDDS x 0.75
—
—
V
VOL
IOL = 2 mA
—
—
VDDS x 0.15
V
Notes:
1. Note that the VOH specification does not apply to the open-drain SDA/SDIO output when the serial interface is in I2C
mode or is unused with I2C_SEL pulled high. VOL remains valid in all cases.
2. VDDIO is determined by the IO_VDD_SEL bit. It is selectable as VDDA or VDD. See the Si5345/44/42 Family Reference
Manual for more details on the proper register settings.
14
Rev. 1.0
Si5 3 4 5 /44/42
Table 8. Performance Characteristics
(VDD = 1.8 V ±5%, VDDA = 3.3 V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
PLL Loop Bandwidth Programming Range1
fBW
Initial Start-Up Time
Test Condition
Min
Typ
Max
Unit
0.1
—
4000
Hz
tSTART
Time from power-up to when the
device generates free-running clocks
—
30
45
ms
tACQ
fIN = 19.44 MHz
—
500
600
ms
tDELAY_frac
fVCO = 14 GHz
—
0.28
—
ps
tDELAY_int
—
71.4
—
ps
tRANGE
—
±9.14
—
ns
POR to Serial Interface
Ready3
tRDY
—
—
15
ms
Jitter Peaking
JPK
Measured with a frequency plan running a 25 MHz input, 25 MHz output,
and a Loop Bandwidth of 4 Hz
—
—
0.1
dB
Jitter Tolerance
JTOL
Compliant with G.8262 Options 1 and
2 Carrier Frequency = 10.3125 GHz
Jitter Modulation
Frequency = 10 Hz
—
3180
—
UI pk-pk
tSWITCH
Only valid for a single switch between
two input clocks running at the same
frequency
—
—
2.8
ns
P
—
500
—
ppm
tIODELAY
—
2
—
ns
PLL Lock Time2
Output Delay Adjustment
Maximum Phase Transient During a Hitless
Switch
Pull-in Range
Input-to-Output Delay
Variation
RMS Phase Jitter4
tZDELAY
In Zero Delay Mode. Measured as the
time delay difference between the reference input and the feedback input,
with both clocks running at 10 MHz
and having the same slew rate. The
rise time of the reference input should
not exceed 200 ps in order to meet
this spec.
—
110
—
ps
JGEN
Integer Mode
12 kHz to 20 MHz
—
0.090
0.140
ps RMS
Fractional Mode
12 kHz to 20 MHz
—
0.130
0.165
ps RMS
Notes:
1. Actual loop bandwidth might be lower; please refer to CBPro for actual value for your frequency plan.
2. Lock Time can vary significantly depending on several parameters, such as bandwidths, LOL tresholds, etc. For this
case, lock time was measured with nominal and fastlock bandwidths set to 100 Hz, LOL set/clear thresholds of 6/0.6
ppm respectively, using IN0 as clock reference by removing the reference and enabling it again, then measuring the
delta time between the first rising edge of the clock reference and the LOL indicator deassertion.
3. Measured as time from valid VDD/VDDA rails (90% of their value) to when the serial interface is ready to respond to
commands.
4. Jitter generation test conditions: fIN = 19.44 MHz, fOUT = 156.25 MHz LVPECL, loop bandwidth = 100 Hz.
Rev. 1.0
15
Si5 345/44/ 42
Table 9. I2C Timing Specifications (SCL,SDA)
Parameter
Symbol
Test Condition
Min
Max
Standard Mode
100 kbps
SCL Clock Frequency
Max
Unit
Fast Mode
400 kbps
—
100
—
400
kHz
25
35
25
35
ms
tHD:STA
4.0
—
0.6
—
μs
Low period of the SCL
clock
tLOW
4.7
—
1.3
—
μs
HIGH period of the SCL
clock
tHIGH
4.0
—
0.6
—
μs
Set-up time for a
repeated START condition
tSU:STA
4.7
—
0.6
—
μs
Data hold time
tHD:DAT
100
—
100
—
ns
Data set-up time
tSU:DAT
250
—
100
—
ns
Rise time of both SDA
and SCL signals
tr
—
1000
20
300
ns
Fall time of both SDA
and SCL signals
tf
—
300
—
300
ns
Set-up time for STOP
condition
tSU:STO
4.0
—
0.6
—
μs
tBUF
4.7
—
1.3
—
μs
Data valid time
tVD:DAT
—
3.45
—
0.9
μs
Data valid acknowledge
time
tVD:ACK
—
3.45
—
0.9
μs
SMBus Timeout
Hold time (repeated)
START condition
Bus free time between a
STOP and START condition
16
fSCL
Min
—
When Timeout is
Enabled
Rev. 1.0
Si5 3 4 5 /44/42
Figure 2. I2C Serial Port Timing Standard and Fast Modes
Rev. 1.0
17
Si5 345/44/ 42
Table 10. SPI Timing Specifications (4-Wire)
(VDD = 1.8 V ±5%, VDDA = 3.3V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Min
Typ
Max
Unit
SCLK Frequency
fSPI
—
—
20
MHz
SCLK Duty Cycle
TDC
40
—
60
%
SCLK Period
TC
50
—
—
ns
Delay Time, SCLK Fall to SDO Active
TD1
—
12.5
18
ns
Delay Time, SCLK Fall to SDO
TD2
—
10
15
ns
Delay Time, CS Rise to SDO Tri-State
TD3
—
10
15
ns
Setup Time, CS to SCLK
TSU1
5
—
—
ns
Hold Time, SCLK Fall to CS
TH1
5
—
—
ns
Setup Time, SDI to SCLK Rise
TSU2
5
—
—
ns
Hold Time, SDI to SCLK Rise
TH2
5
—
—
ns
Delay Time Between Chip Selects (CS)
TCS
2
—
—
TC
Figure 3. 4-Wire SPI Serial Interface Timing
18
Rev. 1.0
Si5 3 4 5 /44/42
Table 11. SPI Timing Specifications (3-Wire)
(VDD = 1.8 V ±5%, VDDA = 3.3V ±5%, TA = –40 to 85 °C)
Parameter
Symbol
Min
Typ
Max
Unit
SCLK Frequency
fSPI
—
—
20
MHz
SCLK Duty Cycle
TDC
40
—
60
%
SCLK Period
TC
50
—
—
ns
Delay Time, SCLK Fall to SDIO Turn-on
TD1
—
12.5
20
ns
Delay Time, SCLK Fall to SDIO Next-bit
TD2
—
10
15
ns
Delay Time, CS Rise to SDIO Tri-State
TD3
—
10
15
ns
Setup Time, CS to SCLK
TSU1
5
—
—
ns
Hold Time, CS to SCLK Fall
TH1
5
—
—
ns
Setup Time, SDI to SCLK Rise
TSU2
5
—
—
ns
Hold Time, SDI to SCLK Rise
TH2
5
—
—
ns
Delay Time Between Chip Selects (CS)
TCS
2
—
—
TC
Figure 4. 3-Wire SPI Serial Interface Timing
Rev. 1.0
19
Si5 345/44/ 42
Table 12. Crystal Specifications
Parameter
Crystal Frequency Range
Symbol
Test Condition
Min
Typ
Max
Unit
fXTAL_48-54
Frequency range for
best jitter performance
48
—
54
MHz
Load Capacitance
CL_48-54
—
8
—
pF
Shunt Capacitance
CO_48-54
—
—
2
pF
Crystal Drive Level
dL_48-54
—
—
200
μW
Equivalent Series Resistance
Crystal Frequency Range
rESR_48-54 Refer to the Si5345/44/42 Family Reference Manual to determine
ESR.
fXTAL_25
—
25
—
MHz
Load Capacitance
CL_25
—
8
—
pF
Shunt Capacitance
CO_25
—
—
3
pF
Crystal Drive Level
dL_25
—
—
200
μW
Equivalent Series Resistance
rESR_25
Refer to the Si5345/44/42 Family Reference Manual to determine
ESR.
Notes:
1. The Si5345/44/42 is designed to work with crystals that meet the specifications in Table 12.
2. Refer to the Si5345/44/42 Family Reference Manual for recommended 48 to 54 MHz crystals.
20
Rev. 1.0
Si5 3 4 5 /44/42
Table 13. Thermal Characteristics
Parameter
Symbol
Test Condition*
Value
Unit
JA
Still Air
22
°C/W
Air Flow 1 m/s
19.4
Air Flow 2 m/s
18.3
Si5345-64QFN
Thermal Resistance
Junction to Ambient
Thermal Resistance
Junction to Case
JC
9.5
Thermal Resistance
Junction to Board
JB
9.4
JB
9.3
JT
0.2
Thermal Resistance
Junction to Top Center
Si5344, Si5342-44QFN
Thermal Resistance
Junction to Ambient
JA
Still Air
22.3
Air Flow 1 m/s
19.4
Air Flow 2 m/s
18.4
Thermal Resistance
Junction to Case
JC
10.9
Thermal Resistance
Junction to Board
JB
9.3
JB
9.2
JT
0.23
Thermal Resistance
Junction to Top Center
°C/W
*Note: Based on PCB Dimension: 3” x 4.5”, PCB Thickness: 1.6 mm, PCB Land/Via: 36, Number of Cu Layers: 4.
Rev. 1.0
21
Si5 345/44/ 42
Table 14. Absolute Maximum Ratings1,2,3,4
Parameter
Symbol
Test Condition
Value
Unit
Storage Temperature Range
TSTG
–55 to +150
°C
DC Supply Voltage
VDD
–0.5 to 3.8
V
VDDA
–0.5 to 3.8
V
VDDO
–0.5 to 3.8
V
VDDS
–0.5 to 3.8
V
Input Voltage Range
Latch-up Tolerance
VI1
IN0 – IN3/FB_IN
–0.85 to 3.8
V
VI2
IN_SEL1, IN_SEL0, RST,
OE, I2C_SEL, FINC, FDEC,
SDI, SCLK, A0/CS, A1,
SDA/SDIO
–0.5 to 3.8
V
VI3
XA/XB
–0.5 to 2.7
V
LU
ESD Tolerance
HBM
Storage Temperature Range
JESD78 Compliant
2.0
kV
TSTG
–55 to 150
°C
Junction Temperature
TJCT
–55 to 150
°C
Soldering Temperature
(Pb-free profile)4
TPEAK
260
°C
TP
20–40
s
Soldering Temperature Time at TPEAK
(Pb-free profile)4
100 pF, 1.5 k
Notes:
1. Permanent device damage may occur if the absolute maximum ratings are exceeded. Functional operation should be
restricted to the conditions as specified in the operational sections of this data sheet. Exposure to absolute maximum
rating conditions for extended periods may affect device reliability.
2. 64-QFN and 44-QFN packages are RoHS-6 compliant.
3. For more packaging information, including MSL rating, go to www.silabs.com/support/quality/pages/
RoHSInformation.aspx.
4. The device is compliant with JEDEC J-STD-020.
22
Rev. 1.0
Si5 3 4 5 /44/42
3. Typical Operating Characteristics
The phase noise plots below were taken under the following conditions: VDD = 1.8 V, VDDA = 3.3 V, VDDS = 3.3 V,
1.8 V, and TA = 25 °C.
Figure 5. Input = 25 MHz; Output = 625 MHz, 2.5 V LVDS
Figure 6. Input = 25 MHz; Output = 156.25 MHz, 2.5 V LVDS
Rev. 1.0
23
Si5 345/44/ 42
Figure 7. Input = 25 MHz; Output = 155.52 MHz, 2.5 V LVDS
24
Rev. 1.0
Si5 3 4 5 /44/42
4. Detailed Block Diagrams
Figure 8. Si5345 Block Diagram
Rev. 1.0
25
Si5 345/44/ 42
Figure 9. Si5344 Block Diagram
26
Rev. 1.0
Si5 3 4 5 /44/42
Figure 10. Si5342 Block Diagram
Rev. 1.0
27
Si5 345/44/ 42
5. Functional Description
The Si5345’s internal DSPLL provides jitter attenuation and any-frequency multiplication of the selected input
frequency. Fractional input dividers (P) allow the DSPLL to perform hitless switching between input clocks (INx)
that are fractionally related. Input switching is controlled manually or automatically using an internal state machine.
The oscillator circuit (OSC) provides a frequency reference which determines output frequency stability and
accuracy while the device is in free-run or holdover mode. The high-performance MultiSynth dividers (N) generate
integer or fractionally related output frequencies for the output stage. A crosspoint switch connects any of the
MultiSynth generated frequencies to any of the outputs. Additional integer division (R) determines the final output
frequency.
5.1. Frequency Configuration
The frequency configuration of the DSPLL is programmable through the serial interface and can also be stored in
non-volatile memory. The combination of fractional input dividers (Pn/Pd), fractional frequency multiplication (Mn/
Md), fractional output MultiSynth division (Nn/Nd), and integer output division (Rn) allows the generation of virtually
any output frequency on any of the outputs. All divider values for a specific frequency plan are easily determined
using the ClockBuilder Pro utility.
5.2. DSPLL Loop Bandwidth
The DSPLL loop bandwidth determines the amount of input clock jitter attenuation. Register configurable DSPLL
loop bandwidth settings in the range of 0.1 Hz to 4 kHz are available for selection. Since the loop bandwidth is
controlled digitally, the DSPLL will always remain stable with less than 0.1 dB of peaking regardless of the loop
bandwidth selection.
5.2.1. Fastlock Feature
Selecting a low DSPLL loop bandwidth (e.g. 0.1 Hz) will generally lengthen the lock acquisition time. The fastlock
feature allows setting a temporary Fastlock Loop Bandwidth that is used during the lock acquisition process.
Higher fastlock loop bandwidth settings will enable the DSPLLs to lock faster. Fastlock Loop Bandwidth settings of
in the range of 100 Hz to 4 kHz are available for selection. The DSPLL will revert to its normal loop bandwidth once
lock acquisition has completed.
5.3. Modes of Operation
Once initialization is complete the DSPLL operates in one of four modes: Free-run Mode, Lock Acquisition Mode,
Locked Mode, or Holdover Mode. A state diagram showing the modes of operation is shown in Figure 11. The
following sections describe each of these modes in greater detail.
5.3.1. Initialization and Reset
Once power is applied, the device begins an initialization period where it downloads default register values and
configuration data from NVM and performs other initialization tasks. Communicating with the device through the
serial interface is possible once this initialization period is complete. No clocks will be generated until the
initialization is complete. There are two types of resets available. A hard reset is functionally similar to a device
power-up. All registers will be restored to the values stored in NVM, and all circuits including the serial interface will
be restored to their initial state. A hard reset is initiated using the RST pin or by asserting the hard reset bit. A soft
reset bypasses the NVM download. It is simply used to initiate register configuration changes.
28
Rev. 1.0
Si5 3 4 5 /44/42
Figure 11. Modes of Operation
5.3.2. Freerun Mode
The DSPLL will automatically enter freerun mode once power is applied to the device and initialization is complete.
The frequency accuracy of the generated output clocks in freerun mode is entirely dependent on the frequency
accuracy of the external crystal or reference clock on the XA/XB pins. For example, if the crystal frequency is
±100 ppm, then all the output clocks will be generated at their configured frequency ±100 ppm in freerun mode.
Any drift of the crystal frequency will be tracked at the output clock frequencies. A TCXO or OCXO is
recommended for applications that need better frequency accuracy and stability while in freerun or holdover
modes.
5.3.3. Lock Acquisition Mode
The device monitors all inputs for a valid clock. If at least one valid clock is available for synchronization, the
DSPLL will automatically start the lock acquisition process. If the fast lock feature is enabled, the DSPLL will
acquire lock using the Fastlock Loop Bandwidth setting and then transition to the DSPLL Loop Bandwidth setting
when lock acquisition is complete. During lock acquisition the outputs will generate a clock that follows the VCO
frequency change as it pulls-in to the input clock frequency.
5.3.4. Locked Mode
Once locked, the DSPLL will generate output clocks that are both frequency and phase locked to their selected
input clocks. At this point any XTAL frequency drift will not affect the output frequency. A loss of lock pin (LOL) and
status bit indicate when lock is achieved. See section 5.7.4 for more details on the operation of the loss of lock
circuit.
5.3.5. Holdover Mode
The DSPLL will automatically enter holdover mode when the selected input clock becomes invalid and no other
valid input clocks are available for selection. The DSPLL uses an averaged input clock frequency as its final
holdover frequency to minimize the disturbance of the output clock phase and frequency when an input clock
suddenly fails. The holdover circuit for the DSPLL stores up to 120 seconds of historical frequency data while
locked to a valid clock input. The final averaged holdover frequency value is calculated from a programmable
window within the stored historical frequency data. Both the window size and the delay are programmable as
shown in Figure 12. The window size determines the amount of holdover frequency averaging. The delay value
allows ignoring frequency data that may be corrupt just before the input clock failure.
Rev. 1.0
29
Si5 345/44/ 42
Figure 12. Programmable Holdover Window
When entering holdover, the DSPLL will pull its output clock frequency to the calculated averaged holdover
frequency. While in holdover, the output frequency drift is entirely dependent on the external crystal or external
reference clock connected to the XA/XB pins. If the clock input becomes valid, the DSPLL will automatically exit the
holdover mode and re-acquire lock to the new input clock. This process involves pulling the output clock frequency
to achieve frequency and phase lock with the input clock. This pull-in process is glitchless and its rate is controlled
by the DSPLL or the Fastlock bandwidth.
5.4. External Reference (XA/XB)
An external crystal (XTAL) is used in combination with the internal oscillator (OSC) to produce an ultra low jitter
reference clock for the DSPLL and for providing a stable reference for the free-run and holdover modes. A
simplified diagram is shown in Figure 13. The device includes internal XTAL loading capacitors which eliminates
the need for external capacitors and also has the benefit of reduced noise coupling from external sources. Refer to
Table 12 for crystal specifications. A crystal in the range of 48 MHz to 54 MHz is recommended for best jitter
performance. Frequency offsets due to CL mismatch can be adjusted using the frequency adjustment feature
which allows frequency adjustments of ±200 ppm. The Si5345/44/42 Family Reference Manual provides additional
information on PCB layout recommendations for the crystal to ensure optimum jitter performance.
The device can also accommodate an external reference clock (REFCLK) instead of a crystal. Selection between
the external XTAL or REFCLK is controlled by register configuration. The internal crystal loading capacitors (CL)
are disabled in this mode. Refer to Table 3 for REFCLK requirements when using this mode. A PREF divider is
available to accommodate external clock frequencies higher than 54 MHz. Frequencies in the range of 48 MHz to
54 MHz will achieve the best output jitter performance.
5.5. Digitally Controlled Oscillator (DCO) Mode
The output MultiSynths support a DCO mode where their output frequencies are adjustable in pre-defined steps
defined by frequency step words (FSW). The frequency adjustments are controlled through the serial interface or
by pin control using frequency increment (FINC) or decrement (FDEC). A FINC will add the frequency step word to
the DSPLL output frequency, while a FDEC will decrement it. Any number of MultiSynths can be can be updated at
once or independently controlled. The DCO mode is available when the DSPLL is operating in either free-run or
locked mode.
30
Rev. 1.0
Si5 3 4 5 /44/42
Figure 13. Crystal Resonator and External Reference Clock Connection Options
5.6. Inputs (IN0, IN1, IN2, IN3)
There are four inputs that can be used to synchronize the DSPLL. The inputs accept both differential and singleended clocks. Input selection can be manual (pin or register controlled) or automatic with user definable priorities.
5.6.1. Manual Input Switching (IN0, IN1, IN2, IN3)
Input clock selection can be made manually using the IN_SEL[1:0] pins or through a register. A register bit
determines input selection as pin selectable or register selectable. The IN_SEL pins are selected by default. If
there is no clock signal on the selected input, the device will automatically enter free-run or holdover mode. When
the zero delay mode is enabled, IN3 becomes the feedback input (FB_IN) and is not available for selection as a
clock input.
Table 15. Manual Input Selection Using IN_SEL[1:0] Pins
Selected Input
IN_SEL[1:0]
Zero Delay
Mode Disabled
Zero Delay
Mode Enabled
0
0
IN0
IN0
0
1
IN1
IN1
1
0
IN2
IN2
1
1
IN3
Reserved
Rev. 1.0
31
Si5 345/44/ 42
5.6.2. Automatic Input Selection (IN0, IN1, IN2, IN3)
An automatic input selection state machine is available in addition to the manual switching option. In automatic
mode, the selection criteria is based on input clock qualification, input priority, and the revertive option. Only input
clocks that are valid can be selected by the automatic clock selection state machine. If there are no valid input
clocks available the DSPLL will enter the holdover mode. With revertive switching enabled, the highest priority
input with a valid input clock is always selected. If an input with a higher priority becomes valid then an automatic
switchover to that input will be initiated. With non-revertive switching, the active input will always remain selected
while it is valid. If it becomes invalid an automatic switchover to a valid input with the highest priority will be
initiated.
5.6.3. Hitless Input Switching
Hitless switching is a feature that prevents a phase transient from propagating to the output when switching
between two clock inputs that have a fixed phase relationship. A hitless switch can only occur when the two input
frequencies are frequency locked meaning that they have to be exactly at the same frequency, or at a fractional
frequency relationship to each other. When hitless switching is enabled, the DSPLL simply absorbs the phase
difference between the two input clocks during a input switch. When disabled, the phase difference between the
two inputs is propagated to the output at a rate determined by the DSPLL Loop Bandwidth. The hitless switching
feature supports clock frequencies down to the minimum input frequency of 8 kHz.
5.6.4. Glitchless Input Switching
The DSPLL has the ability of switching between two input clock frequencies that are up to ±500 ppm apart. The
DSPLL will pull-in to the new frequency using the DSPLL Loop Bandwidth or using the Fastlock Loop Bandwidth if
enabled. The loss of lock (LOL) indicator will assert while the DSPLL is pulling-in to the new clock frequency. There
will be no output runt pulses generated at the output during the transition.
5.6.5. Input Configuration and Terminations
Each of the inputs can be configured as differential or single-ended LVCMOS. The recommended input termination
schemes are shown in Figure 14. Differential signals must be ac-coupled, while single-ended LVCMOS signals can
be ac or dc-coupled. Unused inputs can be disabled and left unconnected when not in use.
32
Rev. 1.0
Si5 3 4 5 /44/42
Figure 14. Termination of Differential and LVCMOS Input Signals
Rev. 1.0
33
Si5 345/44/ 42
5.6.6. Synchronizing to Gapped Input Clocks
The DSPLL supports locking to an input clock that has missing periods. This is also referred to as a gapped clock.
The purpose of gapped clocking is to modulate the frequency of a periodic clock by selectively removing some of
its cycles. Gapping a clock severely increases its jitter so a phase-locked loop with high jitter tolerance and low
loop bandwidth is required to produce a low-jitter periodic clock. The resulting output will be a periodic non-gapped
clock with an average frequency of the input with its missing cycles. For example, an input clock of 100 MHz with
one cycle removed every 10 cycles will result in a 90 MHz periodic non-gapped output clock. This is shown in
Figure 15. For more information on gapped clocks, see “AN561: Introduction to Gapped Clocks and PLLs”.
Figure 15. Generating an Averaged Clock Output Frequency from a Gapped Clock Input
A valid gapped clock input must have a minimum frequency of 10 MHz with a maximum of two missing cycles out
of every 8. Locking to a gapped clock will not trigger the LOS, OOF, and LOL fault monitors. Clock switching
between gapped clocks may violate the hitless switching specification in Table 8 when the switch occurs during a
gap in either input clock.
5.7. Fault Monitoring
All four input clocks (IN0, IN1, IN2, IN3/FB_IN) are monitored for loss of signal (LOS) and out-of-frequency (OOF)
as shown in Figure 16. The reference at the XA/XB pins is also monitored for LOS since it provides a critical
reference clock for the DSPLL. There is also a Loss Of Lock (LOL) indicator which is asserted when the DSPLL
loses synchronization.
Figure 16. Si5345/44/42 Fault Monitors
34
Rev. 1.0
Si5 3 4 5 /44/42
5.7.1. Input LOS Detection
The loss of signal monitor measures the period of each input clock cycle to detect phase irregularities or missing
clock edges. Each of the input LOS circuits has its own programmable sensitivity which allows ignoring missing
edges or intermittent errors. Loss of signal sensitivity is configurable using the ClockBuilder Pro utility.
The LOS status for each of the monitors is accessible by reading a status register. The live LOS register always
displays the current LOS state and a sticky register always stays asserted until cleared. An option to disable any of
the LOS monitors is also available.
Figure 17. LOS Status Indicators
5.7.2. XA/XB LOS Detection
A LOS monitor is available to ensure that the external crystal or reference clock is valid. By default the output
clocks are disabled when XAXB_LOS is detected. This feature can be disabled such that the device will continue to
produce output clocks when XAXB_LOS is detected.
5.7.3. OOF Detection
Each input clock is monitored for frequency accuracy with respect to a OOF reference which it considers as its
“0_ppm” reference.
This OOF reference can be selected as either:
XA/XB pins
 Any input clock (IN0, IN1, IN2, IN3)
The final OOF status is determined by the combination of both a precise OOF monitor and a fast OOF monitor as
shown in Figure 18. An option to disable either monitor is also available. The live OOF register always displays the
current OOF state, and its sticky register bit stays asserted until cleared.

Figure 18. OOF Status Indicator
5.7.3.1. Precision OOF Monitor
The precision OOF monitor circuit measures the frequency of all input clocks to within ±1 ppm accuracy with
respect to the selected OOF frequency reference. A valid input clock frequency is one that remains within the OOF
frequency range which is register configurable from ±2 ppm to ±500 ppm in steps of 2 ppm.
A configurable amount of hysteresis is also available to prevent the OOF status from toggling at the failure
boundary. An example is shown in Figure 19. In this case the OOF monitor is configured with a valid frequency
range of ±6 ppm and with 2 ppm of hysteresis. An option to use one of the input pins (IN0 - IN3) as the 0 ppm OOF
reference instead of the XA/XB pins is available. This option is register configurable.
Rev. 1.0
35
Si5 345/44/ 42
Figure 19. Example of Precise OOF Monitor Assertion and De-assertion Triggers
5.7.3.2. Fast OOF Monitor
Because the precision OOF monitor needs to provide 1 ppm of frequency measurement accuracy, it must measure
the monitored input clock frequencies over a relatively long period of time. This may be too slow to detect an input
clock that is quickly ramping in frequency. An additional level of OOF monitoring called the Fast OOF monitor runs
in parallel with the precision OOF monitors to quickly detect a ramping input frequency. The Fast OOF monitor
asserts OOF on an input clock frequency that has changed by greater than ±4000 ppm.
5.7.4. LOL Detection
The Loss Of Lock (LOL) monitor asserts a LOL register bit when the DSPLL has lost synchronization with its
selected input clock.
There is also a dedicated loss of lock pin that reflects the loss of lock condition. The LOL monitor functions by
measuring the frequency difference between the input and feedback clocks at the phase detector. There are two
LOL frequency monitors, one that sets the LOL indicator (LOL Set) and another that clears the indicator (LOL
Clear). An optional timer is available to delay clearing of the LOL indicator to allow additional time for the DSPLL to
completely lock to the input clock. The timer is also useful to prevent the LOL indicator from toggling or chattering
as the DSPLL completes lock acquisition. A block diagram of the LOL monitor is shown in Figure 20. The live LOL
register always displays the current LOL state and a sticky register always stays asserted until cleared. The LOL
pin reflects the current state of the LOL monitor.
Figure 20. LOL Status Indicators
36
Rev. 1.0
Si5 3 4 5 /44/42
The LOL frequency monitors have an adjustable sensitivity which is register configurable from 0.2 ppm to
20000 ppm. Having two separate frequency monitors allows for hysteresis to help prevent chattering of LOL status.
An example configuration where LOCK is indicated when there is less than 0.2 ppm frequency difference at the
inputs of the phase detector and LOL is indicated when there’s more than 2 ppm frequency difference is shown in
Figure 21.
Figure 21. LOL Set and Clear Thresholds
Note: In this document, the terms, LVDS and LVPECL, refer to driver formats that are compatible with these signaling
standards.
An optional timer is available to delay clearing of the LOL indicator to allow additional time for the DSPLL to
completely lock to the input clock. The timer is also useful to prevent the LOL indicator from toggling or chattering
as the DSPLL completes lock acquisition. The configurable delay value depends on frequency configuration and
loop bandwidth of the DSPLL and is automatically calculated using the ClockBuilder Pro utility.
5.7.5. Interrupt pin (INTR)
An interrupt pin (INTR) indicates a change in state of the status indicators (LOS, OOF, LOL, HOLD). Any of the
status indicators are maskable to prevent assertion of the interrupt pin. The state of the INTR pin is reset by
clearing the status register that caused the interrupt.
Rev. 1.0
37
Si5 345/44/ 42
5.8. Outputs
Each driver has a configurable voltage swing and common mode voltage covering a wide variety of differential
signal formats. In addition to supporting differential signals, any of the outputs can be configured as single-ended
LVCMOS (3.3 V, 2.5 V, or 1.8 V) providing up to 20 single-ended outputs, or any combination of differential and
single-ended outputs.
5.8.1. Output Crosspoint
A crosspoint allows any of the output drivers to connect with any of the MultiSynths as shown in Figure 22. The
crosspoint configuration is programmable and can be stored in NVM so that the desired output configuration is
ready at power up.
Figure 22. MultiSynth to Output Driver Crosspoint
5.8.2. Output Signal Format
The differential output swing and common mode voltage are both fully programmable covering a wide variety of
signal formats including LVDS and LVPECL. In addition to supporting differential signals, any of the outputs can be
configured as LVCMOS (3.3 V, 2.5 V, or 1.8 V) drivers providing up to 20 single-ended outputs, or any combination
of differential and single-ended outputs.
38
Rev. 1.0
Si5 3 4 5 /44/42
5.8.3. Differential Output Terminations
Note: In this document, the terms, LVDS and LVPECL, refer to driver formats that are compatible with these signaling
standards.
The differential output drivers support both ac coupled and dc coupled terminations as shown in Figure 23.
Figure 23. Supported Differential Output Terminations
5.8.4. LVCMOS Output Terminations
LVCMOS outputs are dc-coupled as shown in Figure 24.
Figure 24. LVCMOS Output Terminations
Rev. 1.0
39
Si5 345/44/ 42
5.8.5. Differential Output Swing Modes
There are two selectable differential output swing modes: Normal and Low-Power. Each output can support a
unique mode. Please see the Si5345/44/42 Reference Manual for information on setting the differential output
driver to non-standard amplitudes.
Normal Swing Mode: When an output driver is configured in normal swing mode, its output
swing is selectable as one of 7 settings ranging from 200 mVpp_se to 800 mVpp_se in increments of
100 mV. The output impedance in the Normal Swing Mode is 100differentialAny of the terminations
shown in Figure 23 is supported in this mode.
Differential Low Power Mode: When an output driver is configured in low power mode, its output swing is
configurable as one of 7 settings ranging from 400 mVpp_se to 1600 mVpp_se in increments of 200 mV.
The output driver is in high impedance mode and supports standard 50 PCB traces. Any of the
terminations shown in Figure 23 is supported in this mode.
5.8.6. LVCMOS Output Impedance Selection
Each LVCMOS driver has a configurable output impedance to accommodate different trace impedances. A source
termination resistor is recommended to help match the selected output impedance to the trace impedance, where
Rs = Transmission line impedance – ZO. There are three programmable output impedance selections (CMOS1,
CMOS2, CMOS3) for each VDDO options as shown in Table 16.
Differential
Table 16. Typical Output Impedance (ZS)
CMOS_DRIVE_Selection
VDDO
CMOS1
CMOS2
CMOS3
3.3 V
38 
30 
22 
2.5 V
43 
35 
24 
1.8 V
—
46 
31 
5.8.7. LVCMOS Output Signal Swing
The signal swing (VOL/VOH) of the LVCMOS output drivers is set by the voltage on the VDDO pins. Each output
driver has its own VDDO pin allowing a unique output voltage swing for each of the LVCMOS drivers. Each output
driver automatically detects the voltage on the VDDO pin to properly determine the correct output voltage.
5.8.8. LVCMOS Output Polarity
When a driver is configured as an LVCMOS output it generates a clock signal on both pins (OUTx and OUTx). By
default the clock on the OUTx pin is generated with the same polarity (in phase) with the clock on the OUTx pin.
The polarity of these clocks is configurable enabling complementary clock generation and/or inverted polarity with
respect to other output drivers.
40
Rev. 1.0
Si5 3 4 5 /44/42
5.8.9. Output Enable/Disable
The OE pin provides a convenient method of disabling or enabling the output drivers. When the OE pin is held high
all outputs will be disabled. When held low, the outputs will be enabled. Outputs in the enabled state can be
individually disabled through register control.
5.8.10. Output Driver State When Disabled
The disabled state of an output driver is configurable as: disable low, disable high, or disable high-impedance.
5.8.11. Synchronous Output Disable Feature
The output drivers provide a selectable synchronous disable feature. Output drivers with this feature turned on will
wait until a clock period has completed before the driver is disabled. This prevents unwanted runt pulses from
occurring when disabling an output. When this feature is turned off, the output clock will disable immediately
without waiting for the period to complete.
5.8.12. Output Skew Control (t0 – t4)
The Si5345 uses independent MultiSynth dividers (N0 - N4) to generate up to 5 unique frequencies to its 10 outputs
through a crosspoint switch. By default all clocks are phase aligned. A delay path (t0 - t4) associated with each of
these dividers is available for applications that need a specific output skew configuration. This is useful for PCB
trace length mismatch compensation. The resolution of the phase adjustment is approximately 0.28 ps per step
definable in a range of ±9.14 ns. Phase adjustments are register configurable. An example of generating two
frequencies with unique configurable path delays is shown in Figure 25.
Figure 25. Example of Independently Configurable Path Delays
All phase delay values are restored to their default values after power-up, hard reset, or a reset using the RST pin.
Phase delay default values can be written to NVM allowing a custom phase offset configuration at power-up or
after power-on reset, or after a hardware reset using the RST pin.
Rev. 1.0
41
Si5 345/44/ 42
5.8.13. Zero Delay Mode
A zero delay mode is available for applications that require fixed and consistent minimum delay between the
selected input and outputs. The zero delay mode is configured by opening the internal feedback loop through
software configuration and closing the loop externally as shown in Figure 26.
This helps to cancel out the internal delay introduced by the dividers, the crosspoint, the input, and the output
drivers. Any one of the outputs can be fed back to the FB_IN pins, although using the output driver that achieves
the shortest trace length will help to minimize the input-to-output delay. The OUT9 and FB_IN pins are
recommended for the external feedback connection. The FB_IN input pins must be terminated and ac-coupled
when zero delay mode is used. A differential external feedback path connection is necessary for best performance.
Note that automatic input clock switching and hitless switching features are not available when zero delay mode is
enabled.
Figure 26. Si5345 Zero Delay Mode Setup
5.8.14. Output Divider (R) Synchronization
All the output R dividers are reset to a known state during the power-up initialization period. This ensures
consistent and repeatable phase alignment across all output drivers. Resetting the device using the RST pin or
asserting the hard reset bit will have the same result. Asserting the sync register bit provides another method of realigning the R dividers without resetting the device.
42
Rev. 1.0
Si5 3 4 5 /44/42
5.9. Power Management
Unused inputs and output drivers can be powered down when unused. Consult the Si5345/44/42 Family
Reference Manual and ClockBuilder Pro configuration utility for details.
5.10. In-Circuit Programming
The Si5345/44/42 is fully configurable using the serial interface (I2C or SPI). At power-up the device downloads its
default register values from internal non-volatile memory (NVM). Application specific default configurations can be
written into NVM allowing the device to generate specific clock frequencies at power-up. Writing default values to
NVM is in-circuit programmable with normal operating power supply voltages applied to its VDD and VDDA pins.
The NVM is two time writable. Once a new configuration has been written to NVM, the old configuration is no
longer accessible. Refer to the Si5345/44/42 Family Reference Manual for a detailed procedure for writing
registers to NVM.
5.11. Serial Interface
Configuration and operation of the Si5345/44/42 is controlled by reading and writing registers using the I2C or SPI
interface. The I2C_SEL pin selects I2C or SPI operation. Communication with both 3.3 V and 1.8 V host is
supported. The SPI mode operates in either 4-wire or 3-wire. See the Si5345/44/42 Family Reference Manual for
details.
5.12. Custom Factory Preprogrammed Parts
For applications where a serial interface is not available for programming the device, custom pre-programmed
parts can be ordered with a specific configuration written into NVM. A factory pre-programmed part will generate
clocks at power-up. Custom, factory-preprogrammed devices are available. Use the ClockBuilder Pro custom part
number wizard (www.silabs.com/clockbuilderpro) to quickly and easily request and generate a custom part number
for your configuration.
In less than three minutes, you will be able to generate a custom part number with a detailed data sheet addendum
matching your design’s configuration. Once you receive the confirmation email with the data sheet addendum,
simply place an order with your local Silicon Labs sales representative. Samples of your preprogrammed device
will typically ship in about two weeks.
5.13. Enabling Features and/or Configuration Settings Unavailable in ClockBuilder Pro
for Factory Preprogrammed Devices
As with essentially all modern software utilities, ClockBuilder Pro is continuously updated and enhanced. By
registering at www.silabs.com, you will be notified whenever changes are made and what the impact of those
changes are. This update process will ultimately enable ClockBuilder Pro users to access all features and register
setting values documented in this data sheet and the Si5345/44/42 Family Reference Manual.
However, if you must enable or access a feature or register setting value so that the device starts up with this
feature or a register setting, but the feature or register setting is not yet available in CBPro, you must contact a
Silicon Labs applications engineer for assistance. One example of this type of feature or custom setting is the
customizable output amplitude and common voltages for the clock outputs. After careful review of your project file
and requirements, the Silicon Labs applications engineer will email back your CBPro project file with your specific
features and register settings enabled using what's referred to as the manual "settings override" feature of CBPro.
"Override" settings to match your request(s) will be listed in your design report file. Examples of setting "overrides"
in a CBPro design report are shown in Table 17.
Rev. 1.0
43
Si5 345/44/ 42
Table 17. Setting Overrides
Location
Customer Name
Engineering Name
Type
Target
Dec Value Hex Value
0x0435[0]
FORCE_HOLD_PLLA
OLA_HO_FORCE
No NVM
N/A
1
0x1
0x0B48[0:4]
OOF_DIV_CLK_DIS
OOF_DIV_CLK_DIS
User
OPN&EVB
0
0x00
Once you receive the updated design file, simply open it in CBPro. The device will begin operation after startup
with the values in the NVM file. The flowchart for this process is shown in Figure 27.
Figure 27. Process for Requesting Non-Standard CBPro Features
44
Rev. 1.0
Si5 3 4 5 /44/42
6. Register Map
The register map is divided into multiple pages where each page has 256 addressable registers. Page 0 contains
frequently accessible registers, such as alarm status, resets, device identification, etc. Other pages contain
registers that need less frequent access such as frequency configuration, and general device settings. A high level
map of the registers is shown in “6.2. High-Level Register Map” . Refer to the Si5345/44/42 Family Reference
Manual for a complete list of register descriptions and settings. Silicon Labs strongly recommends using
ClockBuilder Pro to create and manage register settings.
6.1. Addressing Scheme
The device registers are accessible using a 16-bit address which consists of an 8-bit page address + 8-bit register
address. By default the page address is set to 0x00. Changing to another page is accomplished by writing to the
‘Set Page Address’ byte located at address 0x01 of each page.
6.2. High-Level Register Map
Table 18. High-Level Register Map
16-Bit Address
Content
8-bit Page
Address
8-bit Register
Address Range
00
00
Revision IDs
01
Set Page Address
02–0A
Device IDs
0B–15
Alarm Status
17–1B
INTR Masks
1C
Reset controls
1D
FINC, FDEC Control Bits
2B
SPI (3-Wire vs 4-Wire)
2C–E1
Alarm Configuration
E2–E4
NVM Controls
FE
Device Ready Status
01
Set Page Address
08–3A
Output Driver Controls
41–42
Output Driver Disable Masks
FE
Device Ready Status
01
Set Page Address
02–05
XTAL Frequency Adjust
08–2F
Input Divider (P) Settings
30
Input Divider (P) Update Bits
47–6A
Output Divider (R) Settings
6B–72
User Scratch Pad Memory
FE
Device Ready Status
01
02
Rev. 1.0
45
Si5 345/44/ 42
Table 18. High-Level Register Map (Continued)
16-Bit Address
8-bit Page
Address
8-bit Register
Address Range
03
01
Set Page Address
02–37
MultiSynth Divider (N0–N4) Settings
0C
MultiSynth Divider (N0) Update Bit
17
MultiSynth Divider (N1) Update Bit
22
MultiSynth Divider (N2) Update Bit
2D
MultiSynth Divider (N3) Update Bit
38
MultiSynth Divider (N4) Update Bit
39–58
FINC/FDEC Settings N0 - N4
59–62
Output Delay (t) Settings
FE
Device Ready Status
04
87
Zero Delay Mode Set Up
05
0E - 14
Fast Lock Loop Bandwidth
15–1F
Feedback Divider (M) Settings
2A
Input Select Control
2B
Fast Lock Control
2C–35
Holdover Settings
36
Input Clock Switching Mode Select
38–39
Input Priority Settings
3F
Holdover History Valid Data
06–08
00–FF
Reserved
09
01
Set Page Address
1C
Zero Delay Mode Settings
43
Control I/O Voltage Select
49
Input Settings
00–FF
Reserved
10–FF
46
Content
Rev. 1.0
Si5 3 4 5 /44/42
7. Pin Descriptions
Rev. 1.0
47
Si5 345/44/ 42
Table 19. Si5345/44/42 Pin Descriptions
Pin Number
Pin Type1
Function
5
I
6
6
I
Crystal Input
Input pins for external crystal (XTAL). Alternatively these
pins can be driven with an external reference clock (REFCLK). An internal register bit selects XTAL or REFCLK
mode. Default is XTAL mode.
7
4
4
I
X2
10
7
7
I
IN0
63
43
43
I
IN0
64
44
44
I
IN1
1
1
1
I
IN1
2
2
2
I
IN2
14
10
10
I
IN2
15
11
11
I
IN3/FB_IN
61
41
41
I
IN3/FB_IN
62
42
42
I
Pin Name
Si5345
Si5344
Si5342
XA
8
5
XB
9
X1
Inputs
XTAL Shield
Connect these pins directly to the XTAL ground pins. X1,
X2 and the XTAL ground pins should be separated from
the PCB ground plane. Refer to the Si5345/44/42 Family
Reference Manual for layout guidelines. These pins
should be left disconnected when connecting XA/XB pins
to an external reference clock (REFCLK).
Clock Inputs
These pins accept an input clock for synchronizing the
device. They support both differential and single-ended
clock signals. Refer to "5.6.5. Input Configuration and Terminations" on page 32 for input termination options.
These pins are high-impedance and must be terminated
externally. The negative side of the differential input must
be grounded through a capacitor when accepting a single-ended clock.
Clock Input 3/External Feedback Input
By default these pins are used as the fourth clock input
(IN3/IN3). They can also be used as the external feedback input (FB_IN/FB_IN) for the optional zero delay
mode. See section "5.8.13. Zero Delay Mode" on page 42
for details on the optional zero delay mode.
Notes:
1. I = Input, O = Output, P = Power
2. The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3. The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
4. Refer to the Si5345/44/42 Family Reference Manual for more information on register setting names.
48
Rev. 1.0
Si5 3 4 5 /44/42
Table 19. Si5345/44/42 Pin Descriptions (Continued)
Pin Number
Pin Type1
Function
20
O
19
19
O
28
25
25
O
OUT1
27
24
24
O
OUT2
31
31
—
O
OUT2
30
30
—
O
Output Clocks
These output clocks support a programmable signal
swing and common mode voltage. Desired output signal
format is configurable using register control. Termination
recommendations are provided in “5.8.3. Differential Output Terminations” and section “5.8.4. LVCMOS Output
Terminations” . Unused outputs should be left unconnected.
OUT3
35
36
—
O
OUT3
34
35
—
O
OUT4
38
—
—
O
OUT4
37
—
—
O
OUT5
42
—
—
O
OUT5
41
—
—
O
OUT6
45
—
—
O
OUT6
44
—
—
O
OUT7
51
—
—
O
OUT7
50
—
—
O
OUT8
54
—
—
O
OUT8
53
—
—
O
OUT9
59
—
—
O
OUT9
58
—
—
O
Pin Name
Si5345
Si5344
Si5342
OUT0
24
20
OUT0
23
OUT1
Outputs
Notes:
1. I = Input, O = Output, P = Power
2. The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3. The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
4. Refer to the Si5345/44/42 Family Reference Manual for more information on register setting names.
Rev. 1.0
49
Si5 345/44/ 42
Table 19. Si5345/44/42 Pin Descriptions (Continued)
Pin Number
Pin Name
Si5345
Si5344
Si5342
Pin Type1
Function
Serial Interface
I2C_SEL
39
38
38
I
I2C Select2
This pin selects the serial interface mode as I2C
(I2C_SEL = 1) or SPI (I2C_SEL = 0). This pin is internally
pulled up by a ~ 20 k resistor to the voltage selected by
the IO_VDD_SEL register bit.
SDA/SDIO
18
13
13
I/O
Serial Data Interface2
This is the bidirectional data pin (SDA) for the I2C mode,
or the bidirectional data pin (SDIO) in the 3-wire SPI
mode, or the input data pin (SDI) in 4-wire SPI mode.
When in I2C mode, this pin must be pulled-up using an
external resistor of at least 1 k. No pull-up resistor is
needed when is SPI mode. Tie low when unused.
A1/SDO
17
15
15
I/O
Address Select 1/Serial Data Output2
In I2C mode this pin functions as the A1 address input pin
and does not have an internal pull-up or pull-down resistor. In 4-wire SPI mode this is the serial data output (SDO)
pin and drives high to the voltage selected by the
IO_VDD_SEL bit. Leave disconnected when unused.
SCLK
16
14
14
I
Serial Clock Input2
This pin functions as the serial clock input for both I2C and
SPI modes. When in I2C mode, this pin must be pulled-up
using an external resistor of at least 1 k. No pull-up
resistor is needed when in SPI mode. Tie high or low
when unused.
A0/CS
19
16
16
I
Address Select 0/Chip Select2
This pin functions as the hardware controlled address A0
in I2C mode. In SPI mode, this pin functions as the chip
select input (active low). This pin is internally pulled-up by
a ~20 k resistor and can be left unconnected when not
in use.
Notes:
1. I = Input, O = Output, P = Power
2. The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3. The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
4. Refer to the Si5345/44/42 Family Reference Manual for more information on register setting names.
50
Rev. 1.0
Si5 3 4 5 /44/42
Table 19. Si5345/44/42 Pin Descriptions (Continued)
Pin Number
Pin Name
Si5345
Si5344
Si5342
Pin Type1
Function
Control/Status
INTR
12
33
33
O
Interrupt2
This pin is asserted low when a change in device status
has occurred. It should be left unconnected when not in
use.
RST
6
17
17
I
Device Reset2
Active low input that performs power-on reset (POR) of
the device. Resets all internal logic to a known state and
forces the device registers to their default values. Clock
outputs are disabled during reset. This pin is internally
pulled-up and can be left unconnected when not in use.
OE
11
12
12
I
Output Enable2
This pin disables all outputs when held high. This pin is
internally pulled low and can be left unconnected when
not in use.
LOL
47
—
—
O
Loss Of Lock (Si5345)2
This output pin indicates when the DSPLL is locked (high)
or out-of-lock (low). It can be left unconnected when not in
use.
—
27
27
O
Loss Of Lock (Si5344/42)3
This output pin indicates when the DSPLL is locked (high)
or out-of-lock (low). It can be left unconnected when not in
use.
LOS0
—
—
30
O
Loss Of Signal for IN03
This pin indicate a loss of clock at the IN0 pin when low.
LOS1
—
—
31
O
Loss Of Signal for IN13
This pin indicate a loss of clock at the IN1 pin when low.
LOS2
—
—
35
O
Loss Of Signal for IN23
This pin indicate a loss of clock at the IN2 pin when low.
LOS3
—
—
36
O
Loss Of Signal for IN33
This pin indicate a loss of clock at the IN3 pin when low.
LOS_XAXB
—
28
28
O
Loss Of Signal on XA/XB Pins3
This pin indicates a loss of signal at the XA/XB pins when
low.
Notes:
1. I = Input, O = Output, P = Power
2. The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3. The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
4. Refer to the Si5345/44/42 Family Reference Manual for more information on register setting names.
Rev. 1.0
51
Si5 345/44/ 42
Table 19. Si5345/44/42 Pin Descriptions (Continued)
Pin Number
Pin Type1
Function
—
I
Frequency Increment Pin2
This pin is used to step-up the output frequency of a
selected output. The affected output and its frequency
change step size is register configurable. This pin is internally pulled low and can be left unconnected when not in
use.
—
—
I
Frequency Decrement Pin2
This pin is used to step-down the output frequency of a
selected output. The affected output driver and its frequency change step size is register configurable. This pin
is internally pulled low and can be left unconnected when
not in use.
3
3
3
I
IN_SEL1
4
37
37
I
Input Reference Select2
The IN_SEL[1:0] pins are used in manual pin controlled
mode to select the active clock input as shown in
Table 15 on page 31. These pins are internally pulled low.
RSVD
5
—
—
—
20
—
—
—
21
—
—
—
55
—
—
—
56
—
—
—
—
22
22
Pin Name
Si5345
Si5344
Si5342
FINC
48
—
FDEC
25
IN_SEL0
NC
Reserved
These pins are connected to the die. Leave disconnected.
No Connect
These pins are not connected to the die. Leave disconnected.
Notes:
1. I = Input, O = Output, P = Power
2. The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3. The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
4. Refer to the Si5345/44/42 Family Reference Manual for more information on register setting names.
52
Rev. 1.0
Si5 3 4 5 /44/42
Table 19. Si5345/44/42 Pin Descriptions (Continued)
Pin Number
Pin Type1
Function
21
P
32
32
P
60
39
39
P
—
40
40
P
Core Supply Voltage
The device operates from a 1.8 V supply. A 1.0 μF bypass
capacitor should be placed very close to this pin. See the
Si5345/44/42 Family Reference Manual for power supply
filtering recommendations.
13
8
8
P
—
9
9
P
—
26
26
P
—
—
29
P
—
—
34
P
VDDO0
22
18
18
P
VDDO1
26
23
23
P
VDDO2
29
29
—
P
VDDO3
33
34
—
P
VDDO4
36
—
—
P
VDDO5
40
—
—
P
VDDO6
43
—
—
P
VDDO7
49
—
—
P
VDDO8
52
—
—
P
VDDO9
57
—
—
P
GND PAD
—
—
—
P
Pin Name
Si5345
Si5344
Si5342
32
21
46
Power
VDD
VDDA
VDDS
Core Supply Voltage 3.3 V
This core supply pin requires a 3.3 V power source. A
1 μF bypass capacitor should be placed very close to this
pin. See the Si5345/44/42 Family Reference Manual for
power supply filtering recommendations.
Status Output Voltage
The voltage on this pin determines VOL/VOH on the
Si5342/44 LOL_A and LOL_B outputs. Connect to either
3.3 V or 1.8 V. A 1.0 μF bypass capacitor should be
placed very close to this pin.
Output Clock Supply Voltage
Supply voltage (3.3 V, 2.5 V, 1.8 V) for OUTn, OUTn outputs. For unused outputs, leave VDDO pins unconnected.
An alternative option is to connect the VDDO pin to a
power supply and disable the output driver to minimize
current consumption.
Ground Pad
This pad provides connection to ground and must be connected for proper operation. Use as many vias as practical and keep the via length to an internal ground plan as
short as possible.
Notes:
1. I = Input, O = Output, P = Power
2. The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3. The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
4. Refer to the Si5345/44/42 Family Reference Manual for more information on register setting names.
Rev. 1.0
53
Si5 345/44/ 42
8. Ordering Guide
Ordering
Part Number
(OPN)
Number of
Input/Output
Clocks
Output Clock
Frequency Range
(MHz)
Supported
Frequency
Synthesis Modes
Package
4/10
0.001 to 712.5 MHz
Integer
Fractional
64-Lead
9x9 QFN
–40 to 85 °C
44-Lead
7x7 QFN
–40 to 85 °C
44-Lead
7x7 QFN
–40 to 85 °C
Evaluation
Board
—
Temperature
Range
Si5345
Si5345A-B-GM1,2
Si5345B-B-GM1,2
0.001 to 350 MHz
Si5345C-B-GM1,2
0.001 to 712.5 MHz
Si5345D-B-GM1,2
0.001 to 350 MHz
Integer Only
Si5344
Si5344A-B-GM1,2
4/4
0.001 to 712.5 MHz
Si5344B-B-GM1,2
0.001 to 350 MHz
Si5344C-B-GM1,2
0.001 to 712.5 MHz
Si5344D-B-GM1,2
0.001 to 350 MHz
Integer
Fractional
Integer Only
Si5342
Si5342A-B-GM1,2
4/2
0.001 to 712.5 MHz
Si5342B-B-GM1,2
0.001 to 350 MHz
Si5342C-B-GM1,2
0.001 to 712.5 MHz
Si5342D-B-GM1,2
0.001 to 350 MHz
Integer
Fractional
Integer Only
Si5345/44/42-EVB
Si5345-EVB
—
—
—
Si5344-EVB
Si5342-EVB
Notes:
1. Add an R at the end of the OPN to denote tape and reel ordering options.
2. Custom, factory preprogrammed devices are available. Ordering part numbers are assigned by Silicon Labs and the
ClockBuilder Pro software utility. Custom part number format is “Si5345A-Bxxxxx-GM” where “xxxxx” is a unique
numerical sequence representing the preprogrammed configuration.
54
Rev. 1.0
Si5 3 4 5 /44/42
8.1. Ordering Part Number Fields
Rev. 1.0
55
Si5 345/44/ 42
9. Package Outlines
9.1. Si5345 9x9 mm 64-QFN Package Diagram
Figure 28 illustrates the package details for the Si5345. Table 20 lists the values for the dimensions shown in the
illustration.
Figure 28. 64-Pin Quad Flat No-Lead (QFN)
Table 20. Package Dimensions
Dimension
Min
Nom
Max
A
0.80
0.85
0.90
A1
0.00
0.02
0.05
b
0.18
0.25
0.30
D
D2
9.00 BSC
5.10
5.20
e
0.50 BSC
E
9.00 BSC
5.30
E2
5.10
5.20
5.30
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.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
56
Rev. 1.0
Si5 3 4 5 /44/42
9.2. Si5344 and Si5342 7x7 mm 44-QFN Package Diagram
Figure 29 illustrates the package details for the Si5344 and Si5342. Table 21 lists the values for the dimensions
shown in the illustration.
Figure 29. 44-Pin Quad Flat No-Lead (QFN)
Table 21. Package Dimensions
Dimension
Min
Nom
Max
A
0.80
0.85
0.90
A1
0.00
0.02
0.05
b
0.18
0.25
0.30
D
D2
7.00 BSC
5.10
5.20
e
0.50 BSC
E
7.00 BSC
5.30
E2
5.10
5.20
5.30
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.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
Rev. 1.0
57
Si5 345/44/ 42
10. PCB Land Pattern
Figure 30 illustrates the PCB land pattern details for the devices. Table 22 lists the values for the dimensions
shown in the illustration.
Si5344 and Si5342
Si5345
Figure 30. PCB Land Pattern
Table 22. PCB Land Pattern Dimensions
Dimension
Si5345 (Max)
Si5344/42 (Max)
C1
8.90
6.90
C2
8.90
6.90
E
0.50
0.50
X1
0.30
0.30
Y1
0.85
0.85
X2
5.30
5.30
Y2
5.30
5.30
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.
3. All dimensions shown are at Maximum Material Condition (MMC). Least Material Condition is
calculated based on a fabrication Allowance of 0.05 mm.
Solder Mask Design
4. All metal pads are to be non-solder mask defined (NSMD). Clearance between the solder mask
and the metal pad is to be 60 μm minimum, all the way around the pad.
Stencil Design
5. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to
assure good solder paste release.
6. The stencil thickness should be 0.125 mm (5 mils).
7. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter pads.
8. A 3x3 array of 1.25 mm square openings on 1.80 mm pitch should be used for the center ground
pad.
Card Assembly
9. A No-Clean, Type-3 solder paste is recommended.
10. The recommended card reflow profile is per the JEDEC/IPC J-STD-020 specification for Small
Body Components.
58
Rev. 1.0
Si5 3 4 5 /44/42
11. Top Marking
Line
Characters
1
Si534fg-
Description
Base part number and Device Grade for Any-frequency, Any-output, Jitter
Cleaning Clock (single PLL):
f = 5: 10-output Si5345: 64-QFN
f = 4: 4-output Si5344: 44-QFN
f = 2: 2-output Si5342: 44-QFN
g = Device Grade (A, B, C, D). See “8. Ordering Guide” for more information.
– = Dash character.
2
Rxxxxx-GM
3
YYWWTTTTTT
4
R = Product revision. (Refer to “8. Ordering Guide” for latest revision).
xxxxx = Customer specific NVM sequence number. Optional NVM code
assigned for custom, factory pre-programmed devices.
Characters are not included for standard, factory default configured devices.
See Ordering Guide for more information.
-GM = Package (QFN) and temperature range (–40 to +85 °C)
YYWW = Characters correspond to the year (YY) and work week (WW) of package assembly.
TTTTTT = Manufacturing trace code.
Circle w/ 1.6 mm
Pin 1 indicator; left-justified
(64-QFN) or 1.4 mm
(44-QFN) diameter
e4
TW
Pb-free symbol; Center-Justified
TW = Taiwan; Country of Origin (ISO Abbreviation)
Rev. 1.0
59
Si5 345/44/ 42
12. Device Errata
Please log in or register at www.silabs.com to access the device errata document.
60
Rev. 1.0
Si5 3 4 5 /44/42
DOCUMENT CHANGE LIST
Revision 0.9 to Revision 0.95






Removed advanced product information revision
history.
Updated “8. Ordering Guide” and changed
references to Revision B.
Updated parametric tables 2, 3, 5, 6, 7, and 8 to
reflect production characterization.
Updated terminology to align with ClockBuilder Pro
software.
Corrected Table 3 references and specifications
from “LVCMOS - DC coupled” to “Pulsed CMOS DC-Coupled”.
Corrected Table 9 I2C data hold time specification to
100 ns from 5 μs.
Revision 0.95 to Revision 1.0
















Corrected minimum input frequency spec from 10 to
0.008 MHz.
Corrected XAXB minimum input voltage swing spec
from 350 to 365 mV.
Corrected FINC and FDEC update rate from 1 ns to
1 μs.
Corrected PLL lock time spec to 500 ms typical and
600 ms max.
Added common-mode voltage spec for 1.8 V LVDS
(Sub-LVDS) in Table 5.
Updated spec delay time between chip selects in
Tables 10 and 11.
Removed SPI Tr/Tf from Table 10.
Corrected AC Test Configuration Schematic.
Corrected INx voltage swing spec and split into
single-ended and different inputs requirements.
Added typical crosstalk spec for Si5342 and Si5344.
Updated pin descriptions for serial interface.
Updated SPI timing diagrams and spec.
Updated max IDDOx spec for LVDS output from 17
to 18 mA.
Updated max normal mode LVPECL output voltage
swing from 950 to 1000 mVpp_se.
Updated max VCM specs.
Updated output-to-output skew specification.
Rev. 1.0
61
Si5 345/44/ 42
CONTACT INFORMATION
Silicon Laboratories Inc.
400 West Cesar Chavez
Austin, TX 78701
Tel: 1+(512) 416-8500
Fax: 1+(512) 416-9669
Toll Free: 1+(877) 444-3032
Please visit the Silicon Labs Technical Support web page:
https://www.siliconlabs.com/support/pages/contacttechnicalsupport.aspx
and register to submit a technical support request.
Patent Notice
Silicon Labs invests in research and development to help our customers differentiate in the market with innovative low-power, small size, analogintensive mixed-signal solutions. Silicon Labs' extensive patent portfolio is a testament to our unique approach and world-class engineering team.
The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice.
Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from
the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any
liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation
consequential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where
personal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized
application, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages.
Silicon Laboratories and Silicon Labs are trademarks of Silicon Laboratories Inc.
Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders.
62
Rev. 1.0