Si52142

Si52142
PCI-E XPRESS G EN 1, G EN 2, & G EN 3 TW O O UTPUT
C L O C K G ENERATOR WITH 2 5 M H Z R E F E R E N C E C L O C K
Features








PCI-Express Gen 1, Gen 2, Gen 3, 
and Gen 4 common clock compliant 
Gen 3 SRNS Compliant

Two 100 MHz, 125 MHz, or 200 MHz 
differential clock outputs

Supports Serial ATA (SATA) at
100 MHz

Low power, push-pull HCSL
compatible differential outputs
No termination resistors required

Dedicated output enable hardware
pins for each clock output

Dedicated hardware pins for spread

spectrum and frequency control on
differential outputs
Up to two PCI-Express clocks
25 MHz reference clock output
25 MHz crystal input or clock input
Signal integrity tuning
I2C support with readback
capabilities
Triangular spread spectrum profile
for maximum electromagnetic
interference (EMI) reduction
Industrial temperature
–40 to 85 °C
3.3 V power supply
24-pin QFN package
Ordering Information:
See page 18.
VDD_CORE
SCLK
22
SDATA
23
21
20
19
1
1
18 OE_DIFF1
REF
2
17 VDD_DIFF
OE_REF
3
VSS_REF
4
OE_DIFF01
5
VDD_DIFF
6
16 DIFF1
25
GND
15 DIFF1
14 DIFF0
13 DIFF0
7
8
9
10
11
12
VDD_DIFF
1
The Si52142 is a spread-spectrum enabled PCIe clock generator that can source
two PCIe clocks and a 25 MHz reference clock. The device has three hardware
output enable pins for enabling the respective outputs, and two hardware pins to
control spread spectrum and frequency on PCIe clock outputs. In addition to the
hardware control pins, I2C programmability is also available to dynamically control
skew, edge rate, and amplitude on the true, compliment, or both differential
signals on the PCIe clock outputs. This control feature enables optimal signal
integrity as well as optimal EMI signature on the PCIe clock outputs.
Refer to AN636 for signal integrity and configurability. Measuring PCIe clock jitter
is quick and easy with the Silicon Labs PCIe Clock Jitter Tool. Download it for free
at www.silabs.com/pcie-learningcenter.
24
VDD_REF
NC
Description
XOUT
Wireless access point
Routers
NC

NC

Network attached storage
Multi-function printer
SS12

SS02

XIN/CLKIN
Applications
VSS_CORE
Pin Assignments
Notes:
1. Internal 100 kohm pull-up.
2. Internal 100 kohm pull-down.
Patents pending
Functional Block Diagram
REF
XIN/CLKIN
XOUT
DIFF0
PLL1
(SSC)
Divider
DIFF1
SCLK
SDATA
Control & Memory
OE_REF
OE [1:0]
Control
RAM
SS [1:0]
Rev 1.4 4/16
Copyright © 2016 by Silicon Laboratories
Si52142
Si52142
2
Rev 1.4
Si52142
TABLE O F C ONTENTS
Section
Page
1. Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.1. Crystal Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
2.2. OE Pin Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.3. OE Assertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.4. OE Deassertion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
2.5. SS[1:0] Pin Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
3. Test and Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
4. Control Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
4.1. I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
4.2. Data Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
5. Pin Descriptions: 24-Pin QFN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6. Ordering Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7. Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8. Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Document Change List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Rev 1.4
3
Si52142
1. Electrical Specifications
Table 1. DC Electrical Specifications
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
3.3 V Operating Voltage
VDD core
3.3 ± 5%
3.135
3.3
3.465
V
3.3 V Input High Voltage
VIH
Control input pins
2.0
—
VDD + 0.3
V
3.3 V Input Low Voltage
VIL
Control input pins
VSS –
0.3
—
0.8
V
Input High Voltage
VIHI2C
SDATA, SCLK
2.2
—
—
V
Input Low Voltage
VILI2C
SDATA, SCLK
—
—
1.0
V
Input High Leakage Current
IIH
Except internal pull-down
resistors, 0 < VIN < VDD
—
—
5
A
Input Low Leakage Current
IIL
Except internal pull-up resistors, 0 < VIN < VDD
–5
—
—
A
3.3 V Output High Voltage
(Single-Ended Outputs)
VOH
IOH = –1 mA
2.4
—
—
V
3.3 V Output High Voltage
(Single-Ended Outputs)
VOL
IOL = 1 mA
—
—
0.4
V
High-impedance Output Current
IOZ
–10
—
10
µA
Input Pin Capacitance
CIN
1.5
—
5
pF
COUT
—
—
6
pF
LIN
—
—
7
nH
—
—
40
mA
Output Pin Capacitance
Pin Inductance
Dynamic Supply Current
IDD_3.3V
All outputs enabled. Differential clocks with 5” traces
and 2 pF load.
Table 2. AC Electrical Specifications
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
LACC
Measured at VDD/2 differential
—
—
250
ppm
TDC
Measured at VDD/2
45
—
55
%
CLKIN Rising and Falling Slew
Rate
TR/TF
Measured between 0.2 VDD and
0.8 VDD
0.5
—
4.0
V/ns
Cycle to Cycle Jitter
TCCJ
Measured at VDD/2
—
—
250
ps
Long Term Jitter
TLTJ
Measured at VDD/2
—
—
350
ps
Crystal
Long-term Accuracy
Clock Input
Duty Cycle
Notes:
1. Visit www.pcisig.com for complete PCIe specifications.
2. Gen 4 specifications based on the PCI-Express Base Specification 4.0 rev. 0.5.
3. Download the Silicon Labs PCIe Clock Jitter Tool at www.silabs.com/pcie-learningcenter.
4
Rev 1.4
Si52142
Table 2. AC Electrical Specifications (Continued)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
Input High Voltage
VIH
XIN/CLKIN pin
2
—
VDD+0.3
V
Input Low Voltage
VIL
XIN/CLKIN pin
—
—
0.8
V
Input High Current
IIH
XIN/CLKIN pin, VIN = VDD
—
—
35
µA
Input Low Current
IIL
XIN/CLKIN pin, 0 < VIN <0.8
–35
—
—
µA
TDC
Measured at 0 V differential
45
—
55
%
Output-Output Skew
TSKEW
Measured at 0 V differential
—
—
50
ps
Cycle to Cycle Jitter
TCCJ
Measured at 0 V differential
—
35
50
ps
PCIe Gen 1 Pk-Pk Jitter,
Common Clock
Pk-Pk
PCIe Gen 1
0
40
45
ps
PCIe Gen 2 Phase Jitter,
Common Clock
RMSGEN2
10 kHz < F < 1.5 MHz
0
1.8
2.0
ps
1.5 MHz< F < Nyquist Rate
0
1.8
2.0
ps
PCIe Gen 3 Phase Jitter,
Common Clock
RMSGEN3
PLL BW 2–4 MHz
CDR = 10 MHz
0
0.5
0.6
ps
PCIe Gen 3 Phase Jitter,
Separate Reference No
Spread, SRNS
RMSGEN3_SRNS
PLL BW of 2–4 or 2–5 MHz,
CDR = 10 MHz
—
0.35
0.42
ps
PCIe Gen 4 Phase Jitter,
Common Clock
RMSGEN4
PLL BW of 2–4 or 2–5 MHz,
CDR = 10 MHz
—
0.5
0.6
ps
LACC
Measured at 0 V differential
—
—
100
ppm
Rising/Falling Slew Rate
T R / TF
Measured differentially from
±150 mV
1
—
8
V/ns
Voltage High
VHIGH
—
—
1.15
V
Voltage Low
VLOW
–0.3
—
—
V
Crossing Point Voltage at
0.7 V Swing
VOX
300
—
550
mV
Spread Range
SPR
—
–0.5
—
%
Modulation Frequency
FMOD
30
31.5
33
kHz
DIFF at 0.7 V
Duty Cycle
Long Term Accuracy
Down spread
Notes:
1. Visit www.pcisig.com for complete PCIe specifications.
2. Gen 4 specifications based on the PCI-Express Base Specification 4.0 rev. 0.5.
3. Download the Silicon Labs PCIe Clock Jitter Tool at www.silabs.com/pcie-learningcenter.
Rev 1.4
5
Si52142
Table 2. AC Electrical Specifications (Continued)
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
TDC
Measurement at 1.5 V
45
—
55
%
TR / TF
Measured between 0.8 and 2.0 V
1.0
—
4.0
V/ns
Cycle to Cycle Jitter
TCCJ
Measurement at 1.5 V
—
—
300
ps
Long Term Accuracy
LACC
Measured at 1.5 V
—
—
100
ppm
Clock Stabilization from
Power-up
TSTABLE
Measured from the point both VDD
and clock input are valid
—
—
1.8
ms
Stopclock Set-up Time
TSS
10.0
—
—
ns
REF(25 MHz) at 3.3 V
Duty Cycle
Rising and Falling Edge Rate
Enable/Disable and Set-Up
Notes:
1. Visit www.pcisig.com for complete PCIe specifications.
2. Gen 4 specifications based on the PCI-Express Base Specification 4.0 rev. 0.5.
3. Download the Silicon Labs PCIe Clock Jitter Tool at www.silabs.com/pcie-learningcenter.
Table 3. Absolute Maximum Conditions
Parameter
Symbol
Test Condition
Min
Typ
Max
Unit
VDD_3.3V
Functional
—
—
4.6
V
Input Voltage
VIN
Relative to VSS
–0.5
—
4.6
VDC
Temperature, Storage
TS
Non-functional
–65
—
150
°C
Temperature, Operating Ambient
TA
Functional
–40
—
85
°C
Temperature, Junction
TJ
Functional
—
—
150
°C
Dissipation, Junction to Case
ØJC
JEDEC (JESD 51)
—
—
25
°C/W
Dissipation, Junction to Ambient
ØJA
JEDEC (JESD 51)
—
—
37
°C/W
ESDHBM
JEDEC (JESD 22-A114)
2000
—
—
V
UL-94
UL (Class)
Main Supply Voltage
ESD Protection (Human Body Model)
Flammability Rating
V–0
Note: While using multiple power supplies, the voltage on any input or I/O pin cannot exceed the power pin during power-up. Power
supply sequencing is not required.
6
Rev 1.4
Si52142
2. Functional Description
2.1. Crystal Recommendations
If using crystal input, the device requires a parallel resonance 25 MHz crystal.
Table 4. Crystal Recommendations
Frequency
(Fund)
Cut
Loading Load Cap
25 MHz
AT
Parallel
12–15 pF
Shunt
Cap (max)
Motional
(max)
Tolerance
(max)
Stability
(max)
Aging
(max)
5 pF
0.016 pF
35 ppm
30 ppm
5 ppm
2.1.1. Crystal Loading
Crystal loading is critical for ppm accuracy. In order to achieve low/zero ppm error, use the calculations below in
section 2.1.2 to estimate the appropriate capacitive loading (CL).
Figure 1 shows a typical crystal configuration using two trim capacitors. It is important that the trim capacitors are in
series with the crystal.
Figure 1. Crystal Capacitive Clarification
2.1.2. Calculating Load Capacitors
In addition to the standard external trim capacitors, consider the trace capacitance and pin capacitance to calculate
the crystal loading correctly. The capacitance on each side is in series with the crystal. The total capacitance on
both sides is twice the specified crystal load capacitance (CL). Trim capacitors are calculated to provide equal
capacitive loading on both sides.
Figure 2. Crystal Loading Example
Use the following formulas to calculate the trim capacitor values for Ce1 and Ce2.
Rev 1.4
7
Si52142
Load Capacitance (each side)
Ce = 2 x CL – (Cs + Ci)
Total Capacitance (as seen by the crystal)
CLe
=
1
1
( Ce1 + Cs1
+ Ci1 +
1
Ce2 + Cs2 + Ci2
)
CL:
Crystal load capacitance
CLe: Actual loading seen by crystal using standard value trim capacitors
Ce: External trim capacitors
Cs: Stray capacitance (terraced)
Ci : Internal capacitance (lead frame, bond wires, etc.)
2.2. OE Pin Definition
The OE pins are active high inputs used to enable and disable the output clocks. To enable the output clock, the OE
pin needs to be logic high and the I2C output enable bit needs to be logic high. There are two methods to disable
the output clocks: the OE is pulled to a logic low, or the I2C enable bit is set to a logic low. The OE pins is required
to be driven at all time and even though it has an internally 100 k resistor.
2.3. OE Assertion
The OE signals are active high input used for synchronous stopping and starting the output clocks respectively while
the rest of the clock generator continues to function. The assertion of the OE signal by making it logic high causes
stopped respective output clocks to resume normal operation. No short or stretched clock pulses are produced when
the clock resumes. The maximum latency from the assertion to active outputs is no more than two to six output clock
cycles.
2.4. OE Deassertion
When the OE pin is deasserted by making its logic low, the corresponding output clocks are stopped cleanly, and
the final output state is driven low.
2.5. SS[1:0] Pin Definition
SS[1:0] are active inputs used to select differential output frequency and enable spread of –0.5% on all DIFF
outputs as per Table 5.
Table 5. SS0 and SS1 Frequency/Spread Selection
8
SS1
SS0
Differential
Frequency
Differential
Spread
Configuration
0
0
100 MHz
Spread Off
Default
0
1
100 MHz
–0.50%
1
0
125 MHz
Spread Off
1
1
200 MHz
Spread Off
Rev 1.4
Si52142
3. Test and Measurement Setup
Figure 3 shows the test load configuration for the HCSL compatible clock outputs.
M e a s u re m e n t
P o in t
L1
O UT+
50 
2 pF
L1 = 5"
M e a s u re m e n t
P o in t
L1
O UT-
50 
2 pF
Figure 3. 0.7 V Differential Load Configuration
Please reference application note AN781 for recommendations on how to terminate the differential outputs for
LVDS, LVPECL, or CML signaling levels.
Figure 4. Differential Measurement for Differential Output Signals
(for AC Parameters Measurement)
Rev 1.4
9
Si52142
VMIN = –0.30V
VMIN = –0.30V
Figure 5. Single-ended Measurement for Differential Output Signals
(for AC Parameters Measurement)
L1 = 0.5", L2 = 5"
Measurement
50
SE Clocks
Point
L1
33 
L2
4 pF
Figure 6. Single-ended Clocks with Single Load Configuration
Figure 7. Single-ended Output Signal (for AC Parameter Measurement)
10
Rev 1.4
Si52142
4. Control Registers
4.1. I2C Interface
To enhance the flexibility and function of the clock synthesizer, an I2C interface is provided. Through the I2C
Interface, various device functions are available, such as individual clock enablement. The registers associated
with the I2C Interface initialize to their default setting at power-up. The use of this interface is optional. Clock device
register changes are normally made at system initialization, if any are required. Power management functions can
only be programed in program mode and not in normal operation modes.
4.2. Data Protocol
The clock driver I2C protocol accepts byte write, byte read, block write, and block read operations from the
controller. For block write/read operation, access the bytes in sequential order from lowest to highest (most
significant bit first) with the ability to stop after any complete byte is transferred. For byte write and byte read
operations, the system controller can access individually indexed bytes.
The block write and block read protocol is outlined in Table 6 while Table 7 outlines byte write and byte read
protocol. The slave receiver address is 11010110 (D6h).
Table 6. Block Read and Block Write Protocol
Block Write Protocol
Bit
1
8:2
Block Read Protocol
Description
Bit
1
Start
8:2
Slave address—7 bits
Description
Start
Slave address—7 bits
9
Write
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
18:11
Command Code—8 bits
18:11
Command Code—8 bits
19
Acknowledge from slave
19
Acknowledge from slave
Byte Count—8 bits
20
Repeat start
27:20
28
36:29
37
45:38
Acknowledge from slave
27:21
Slave address—7 bits
Data byte 1—8 bits
28
Read = 1
Acknowledge from slave
29
Acknowledge from slave
Data byte 2—8 bits
46
Acknowledge from slave
....
Data Byte /Slave Acknowledges
....
Data Byte N—8 bits
....
Acknowledge from slave
....
Stop
37:30
38
46:39
47
55:48
Rev 1.4
Byte Count from slave—8 bits
Acknowledge
Data byte 1 from slave—8 bits
Acknowledge
Data byte 2 from slave—8 bits
56
Acknowledge
....
Data bytes from slave/Acknowledge
....
Data Byte N from slave–8 bits
....
NOT Acknowledge
....
Stop
11
Si52142
Table 7. Byte Read and Byte Write Protocol
Byte Write Protocol
Bit
1
8:2
Byte Read Protocol
Description
Bit
Start
1
Slave address–7 bits
8:2
Start
Slave address–7 bits
9
Write
9
Write
10
Acknowledge from slave
10
Acknowledge from slave
18:11
19
27:20
Command Code–8 bits
18:11
Command Code–8 bits
Acknowledge from slave
19
Acknowledge from slave
Data byte–8 bits
20
Repeated start
28
Acknowledge from slave
29
Stop
27:21
Rev 1.4
Slave address–7 bits
28
Read
29
Acknowledge from slave
37:30
12
Description
Data from slave–8 bits
38
NOT Acknowledge
39
Stop
Si52142
Control Register 0. Byte 0
Bit
D7
D6
D5
D4
D3
D1
D0
R/W
R/W
R/W
REF_OE
Name
Type
D2
R/W
R/W
R/W
R/W
R/W
Reset settings = 00000100
Bit
Name
Function
7:3
Reserved
2
REF_OE
Output Enable for REF.
0: Output disabled.
1: Output enabled.
1:0
Reserved
Control Register 1. Byte 1
Bit
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Name
Type
Reset settings = 00000000
Bit
Name
7:0
Reserved
Function
Rev 1.4
13
Si52142
Control Register 2. Byte 2
Bit
D7
D6
Name
DIFF0_OE
DIFF1_OE
Type
R/W
R/W
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
D2
D1
D0
Reset settings = 11000000
Bit
Name
7
DIFF0_OE
Function
Output Enable for DIFF0.
0: Output disabled.
1: Output enabled.
6
DIFF1_OE
Output Enable for DIFF1.
0: Output disabled.
1: Output enabled.
5:0
Reserved
Control Register 3. Byte 3
Bit
D7
D6
Name
Type
D5
D4
D3
Rev Code[3:0]
R/W
R/W
R/W
Vendor ID[3:0]
R/W
R/W
R/W
R/W
R/W
D3
D2
D1
D0
R/W
R/W
R/W
R/W
Reset settings = 00001000
Bit
Name
Function
7:4
Rev Code[3:0]
Program Revision Code.
3:0
Vendor ID[3:0]
Vendor Identification Code.
Control Register 4. Byte 4
Bit
D7
D6
D5
D4
Name
Type
BC[7:0]
R/W
R/W
R/W
R/W
Reset settings = 00000110
14
Bit
Name
7:0
BC[7:0]
Function
Byte Count Register.
Rev 1.4
Si52142
Control Register 5. Byte 5
Bit
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
Name DIFF_Amp_Sel DIFF_Amp_Cntl[2] DIFF_Amp_Cntl[1] DIFF_Amp_Cntl[0]
Type
R/W
R/W
R/W
R/W
Reset settings = 11011000
Bit
Name
7
DIFF_Amp_Sel
Function
Amplitude Control for DIFF Differential Outputs.
0: Differential outputs with Default amplitude.
1: Differential outputs amplitude is set by Byte 5[6:4].
6
DIFF_Amp_Cntl[2]
5
DIFF_Amp_Cntl[1]
4
DIFF_Amp_Cntl[0]
3:0
Reserved
DIFF Differential Outputs Amplitude Adjustment.
000: 300 mV 001: 400 mV 010: 500 mV
100: 700 mV 101: 800 mV 110: 900 mV
Rev 1.4
011: 600 mV
111: 1000 mV
15
Si52142
VSS_CORE
XIN/CLKIN
XOUT
VDD_CORE
SDATA
SCLK
5. Pin Descriptions: 24-Pin QFN
24
23
22
21
20
19
VDD_REF
1
1
18 OE_DIFF1
REF
2
17 VDD_DIFF
OE_REF1
3
VSS_REF
4
OE_DIFF01
5
VDD_DIFF
6
16 DIFF1
25
GND
15 DIFF1
14 DIFF0
7
8
9
10
11
12
SS02
SS12
NC
NC
NC
VDD_DIFF
13 DIFF0
Notes:
1. Internal 100 kohm pull-up.
2. Internal 100 kohm pull-down.
Table 8. Si52142 24-Pin QFN Descriptions
Pin #
Name
1
VDD_REF
2
REF
3
OE_REF
I,PU
Active high input pin to enable or disable REF clock (internal 100 k
pull-up).
4
VSS_REF
GND
Ground.
5
OE_DIFF0
I,PU
Active high input pin to enable or disable DIFF0 clock (internal 100 k
pull-up).
6
VDD_DIFF
PWR 3.3 V power supply.
7
SS0
I, PD
8
SS1
I, PD
9
NC
NC
No Connect.
10
NC
NC
No connect.
16
Type
Description
PWR 3.3 V power supply.
O, SE 3.3 V, 25 MHz crystal reference clock output.
3.3 V tolerant latch-input for enabling Frequency/ Spread selection on
DIFF0 and DIFF1 outputs. Refer to Table 1 on page 4 for SS[1:0] specifications (internal 100 k pull-down).
Rev 1.4
Si52142
Table 8. Si52142 24-Pin QFN Descriptions (Continued)
Pin #
Name
Type
Description
11
NC
NC
12
VDD_DIFF
13
DIFF0
O, DIF 0.7 V, 100 MHz differential clock output.
14
DIFF0
O, DIF 0.7 V, 100 MHz differential clock output.
15
DIFF1
O, DIF 0.7 V, 100 MHz differential clock output.
16
DIFF1
O, DIF 0.7 V, 100 MHz differential clock output.
17
VDD_DIFF
PWR 3.3 V power supply.
18
OE_DIFF1
I,PU
19
SCLK
I
20
SDATA
I/O
21
VDD_CORE
22
XOUT
O
25.00 MHz Crystal output, Float XOUT if using only CLKIN (Clock input).
23
XIN/CLKIN
I
25.00 MHz Crystal input or 3.3 V, 25 MHz Clock Input.
24
VSS_CORE
GND
Ground.
25
GND
GND
Ground for bottom pad of the IC.
No connect.
PWR 3.3 V power supply.
Active high input pin to enable or disable DIFF1 clock (internal 100 k
pull-up).
I2C SCLOCK.
I2C SDATA.
PWR 3.3 V power supply.
Rev 1.4
17
Si52142
6. Ordering Guide
Part Number
Package Type
Temperature
Si52142-A01AGM
24-pin QFN
Industrial, –40 to 85 C
Si52142-A01AGMR
24-pin QFN—Tape and Reel
Industrial, –40 to 85 C
Lead-free
18
Rev 1.4
Si52142
7. Package Outline
Figure 8 illustrates the package details for the Si52142. Table 9 lists the values for the dimensions shown in the
illustration.
Figure 8. 24-Pin Quad Flat No Lead (QFN) Package
Table 9. Package Diagram Dimensions
Symbol
Millimeters
Min
Nom
Max
0.70
0.75
0.80
A1
0.00
0.025
0.05
b
0.20
0.25
0.30
A
D
D2
4.00 BSC
2.60
2.70
e
0.50 BSC
E
4.00 BSC
2.80
E2
2.60
2.70
2.80
L
0.30
0.40
0.50
aaa
0.10
bbb
0.10
ccc
0.08
ddd
0.07
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 JEDEC outline MO-220, variation VGGD-8.
4. Recommended card reflow profile is per the JEDEC/IPC J-STD-020
specification for Small Body Components.
Rev 1.4
19
Si52142
8. Land Pattern
Figure 9. QFN Land Pattern
Table 10. Land Pattern Dimensions
20
Dimension
Unit mm
C1
4.0
C2
4.0
E
0.50 BSC
X1
0.30
X2
2.70
Y1
0.80
Rev 1.4
Si52142
Table 10. Land Pattern Dimensions (Continued)
Y2
2.70
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
3. 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
4. A stainless steel, laser-cut and electro-polished stencil with trapezoidal walls should be used to assure good solder
paste release.
5. The stencil thickness should be 0.125 mm (5 mils).
6. The ratio of stencil aperture to land pad size should be 1:1 for all perimeter
7. pads.
8. A 2x2 array of 1.10 mm x 1.10 mm openings on 1.30mm 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.
Rev 1.4
21
Si52142
DOCUMENT CHANGE LIST
Revision 0.1 to Revision 1.0









Updated Features on page 1.
Updated Description on page 1.
Updated Table 1 on page 4.
Updated Table 2 on page 5.
Updated Section 2.1 on page 7.
Updated Section 2.1.1 on page 7.
Updated Section 4.1 on page 11.
Updated Section 4.2 on page 11.
Updated Pin Descriptions on page 16.
Revision 1.0 to Revision 1.1

Removed Moisture Sensitivity Level specification
from Table 3.
Revision 1.1 to Revision 1.2


Updated Table 2.
Updated Section 3.
Revision 1.2 to Revision 1.3

Updated Features on page 1.
 Updated Description on page 1.
 Updated Table 2, “AC Electrical Specifications,” on
page 4.
Revision 1.3 to Revision 1.4

22
Added test condition for Tstable in Table 2.
Rev 1.4
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