LMK01801BISQX/NOPB [TI]

双路时钟分配 | RHS | 48 | -40 to 85;
LMK01801BISQX/NOPB
型号: LMK01801BISQX/NOPB
厂家: TEXAS INSTRUMENTS    TEXAS INSTRUMENTS
描述:

双路时钟分配 | RHS | 48 | -40 to 85

时钟 驱动 时钟驱动器
文件: 总39页 (文件大小:487K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
January 16, 2012  
LMK01801  
Dual Clock Divider Buffer  
1.0 General Description  
The LMK01801 is a very low noise solution for clocking sys-  
tems that require distribution and frequency division of preci-  
sion clocks.  
The LMK01801 features extremely low residual noise, fre-  
quency division, digital and analog delay adjustments, and  
fourteen (14) programmable differential outputs: LVPECL,  
LVDS and LVCMOS (2 outputs per differential output).  
3.0 Features  
Pin control mode or MICROWIRE (SPI)  
Input and Output Frequency Range 1 kHz to 3.1 GHz  
Separate Input for Clock Output Banks A & B.  
14 Differential Clock Outputs in Two Banks (A & B)  
Output Bank A  
8 Differential, programmable outputs (Up to 8 as  
LVCMOS)  
The LMK01801 features two independent inputs that can be  
driven differentially (LVDS, LVPECL) or in single-ended mode  
(LVCMOS, RF Sinewave). The first input drives output Bank  
A consisting of eight (8) outputs. The second input drives out-  
put Bank B consisting of six (6) outputs.  
Divider Values of 1 to 8, Even and Odd.  
Output Bank B  
6 Differential Outputs (or up to 12 as LVCMOS)  
Divides values of 1 to 1045 or 1 to 8, even and odd  
Analog and Digital Delays  
2.0 Target Applications  
50% duty cycle on all outputs for all divides  
Separate Synchronization of Bank A and B.  
RMS Additive jitter 50 fs at 800 MHz  
High performance clock distribution and division  
Wireless infrastructure  
Datacom and telecom clock distribution  
Medical imaging  
Test and measurement  
Military / Aerospace  
50 fs RMS Additive jitter (12 kHz to 20 MHz)  
Industrial Temperature Range: -40 to 85 °C  
3.15 V to 3.45 V operation  
Package: 48-pin LLP (7.0 x 7.0 x 0.8 mm)  
30148701  
TRI-STATE® is a registered trademark of National Semiconductor Corporation.  
PLLatinum™ is a trademark of National Semiconductor Corporation.  
© 2012 Texas Instruments Incorporated  
301487 SNAS573  
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Table of Contents  
1.0 General Description ......................................................................................................................... 1  
2.0 Target Applications .......................................................................................................................... 1  
3.0 Features ........................................................................................................................................ 1  
4.0 Functional Configurations ................................................................................................................. 4  
5.0 Connection Diagram ........................................................................................................................ 5  
6.0 Pin Descriptions .............................................................................................................................. 6  
7.0 Absolute Maximum Ratings .............................................................................................................. 8  
8.0 Package Thermal Resistance ............................................................................................................ 8  
9.0 Recommended Operating Conditions ................................................................................................ 8  
10.0 Electrical Characteristics ................................................................................................................. 9  
11.0 Typical Performance Characteristics .............................................................................................. 13  
12.0 Serial MICROWIRE Timing Diagram .............................................................................................. 14  
13.0 Measurement Definitions .............................................................................................................. 15  
13.1 DIFFERENTIAL VOLTAGE MEASUREMENT TERMINOLOGY ................................................. 15  
14.0 Features ..................................................................................................................................... 16  
14.1 SYSTEM ARCHITECTURE ................................................................................................... 16  
14.2 HIGH SPEED CLOCK INPUTS (CLKin0/CLKin0* and CLKin1/CLKin1*) ....................................... 16  
14.3 CLOCK DISTRIBUTION ....................................................................................................... 16  
14.4 SMALL DIVIDER (1 to 8) ....................................................................................................... 16  
14.5 LARGE DIVIDER (1 to 1045 ) ................................................................................................ 16  
14.6 CLKout ANALOG DELAY ...................................................................................................... 16  
14.7 CLKout12 & CLKout13 DIGITAL DELAY .................................................................................. 16  
14.8 PROGRAMMABLE OUTPUTS ............................................................................................... 16  
14.9 CLOCK OUTPUT SYNCHRONIZATION .................................................................................. 16  
14.10 DEFAULT CLOCK OUTPUTS .............................................................................................. 16  
15.0 Functional Description .................................................................................................................. 17  
15.1 PROGRAMMABLE MODE ..................................................................................................... 17  
15.2 PIN CONTROL MODE .......................................................................................................... 17  
15.3 INPUTS / OUTPUTS ............................................................................................................. 17  
15.3.1 CLKin0 and CLKin1 .................................................................................................... 17  
15.4 INPUT AND OUTPUT DIVIDERS ........................................................................................... 17  
15.5 FIXED DIGITAL DELAY ........................................................................................................ 17  
15.5.1 Fixed Digital Delay - Example ....................................................................................... 17  
15.6 CLOCK OUTPUT SYNCHRONIZATION (SYNC) ...................................................................... 18  
15.6.1 Dynamically Programming Digital Delay ......................................................................... 20  
15.6.1.1 RELATIVE DYNAMIC DIGITAL DELAY ............................................................... 21  
15.6.1.2 RELATIVE DYNAMIC DIGITAL DELAY - EXAMPLE ............................................. 21  
16.0 General Programming Information ................................................................................................. 23  
16.1 RECOMMENDED PROGRAMMING SEQUENCE .................................................................... 23  
16.1.1 Overview ................................................................................................................... 23  
16.2 REGISTER MAP .................................................................................................................. 23  
16.3 DEFAULT DEVICE REGISTER SETTINGS AFTER POWER ON/RESET .................................... 25  
16.4 REGISTER R0 ..................................................................................................................... 27  
16.4.1 RESET ...................................................................................................................... 27  
16.4.2 POWERDOWN .......................................................................................................... 27  
16.4.3 CLKoutX_Y_PD ......................................................................................................... 27  
16.4.3.1 CLKinX_BUF_TYPE ......................................................................................... 27  
16.4.3.2 CLKinX_DIV ..................................................................................................... 27  
16.4.3.3 CLKinX_MUX ................................................................................................... 27  
16.5 REGISTER R1 AND R2 ........................................................................................................ 27  
16.5.1 CLKoutX_TYPE ......................................................................................................... 27  
16.6 REGISTER R3 ..................................................................................................................... 28  
16.6.1 CLKout12_13_ADLY ................................................................................................... 28  
16.6.2 CLKout12_13_HS, Digital Delay Half Shift ..................................................................... 28  
16.6.3 SYNC1_QUAL ........................................................................................................... 29  
16.6.4 SYNCX_POL_INV ...................................................................................................... 29  
16.6.5 NO_SYNC_CLKoutX_Y ............................................................................................... 29  
16.6.6 SYNCX_FAST ........................................................................................................... 29  
16.6.7 SYNCX_AUTO ........................................................................................................... 29  
16.7 REGISTER R4 ..................................................................................................................... 29  
16.7.1 CLKout12_13_DDLY, Clock Channel Digital Delay .......................................................... 29  
16.8 REGISTER R5 ..................................................................................................................... 30  
16.8.1 CLKout12_ADLY_SEL[13], CLKout13_ADLY_SEL[14], Select Analog Delay ...................... 30  
16.8.2 CLKoutX_Y_DIV. Clock Output Divide ........................................................................... 30  
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2
16.9 REGISTER 15 ..................................................................................................................... 30  
16.9.1 uWireLock ................................................................................................................. 30  
17.0 Application Information ................................................................................................................. 31  
17.1 POWER SUPPLY ................................................................................................................. 31  
17.1.1 Current Consumption .................................................................................................. 31  
17.2 PIN CONNECTION RECOMMENDATIONS ............................................................................. 33  
17.2.1 Vcc Pins and Decoupling ............................................................................................. 33  
17.2.2 Unused clock outputs .................................................................................................. 33  
17.2.3 Unused clock inputs .................................................................................................... 33  
17.2.4 Bias .......................................................................................................................... 33  
17.2.5 In MICROWIRE Mode ................................................................................................. 33  
17.3 THERMAL MANAGEMENT ................................................................................................... 33  
17.4 DRIVING CLKin INPUTS ....................................................................................................... 34  
17.4.1 Driving CLKin Pins with a Differential Source .................................................................. 34  
17.4.2 Driving CLKin Pins with a Single-Ended Source .............................................................. 34  
17.5 TERMINATION AND USE OF CLOCK OUTPUT (DRIVERS) ..................................................... 34  
17.5.1 Termination for DC Coupled Differential Operation .......................................................... 35  
17.5.2 Termination for AC Coupled Differential Operation .......................................................... 35  
17.5.3 Termination for Single-Ended Operation ........................................................................ 35  
18.0 Physical Dimensions .................................................................................................................... 37  
19.0 Ordering Information .................................................................................................................... 37  
3
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4.0 Functional Configurations  
TABLE 1. Clock Output Configurations  
Output  
CLKoutX/  
CLKoutX*  
Outputs in  
Divider  
Group  
Divider  
Ratios  
Bank  
Input  
Clock Group  
CG1  
Output Type  
Delay  
No  
LVDS/  
LVPECL  
0 to 3  
0 to 3  
4 to 7  
1 to 8  
1 to 8  
CLKin0/  
CLKin0*  
A
LVDS/  
LVPECL/  
LVCMOS  
CG2  
4 to 7  
No  
LVDS/  
CG3  
CG4  
8 to 11  
LVPECL/  
LVCMOS  
8 to 11  
1 to 8  
No  
CLKin1/  
CLKin1*  
B
LVDS/  
LVPECL/  
LVCMOS  
Digital and  
Analog  
(Note 2)  
1 to 1045  
(Note 1)  
12 and 13  
12 and 13  
TABLE 2. Pin Control Mode for EN_PIN_CTRL = Low  
Pin  
Output Groups  
Pin=Low  
LVDS  
Pin=Middle  
Powerdown  
Pin=High  
CLKoutTYPE_0  
CLKoutTYPE_1  
CLKoutTYPE_2  
CLKout0 to CLKout3  
CLKout4 to CLKout7  
CLKout8 to CLKout13  
LVPECL  
LVPECL  
LVPECL  
LVDS  
LVCOMS (Norm/Inv)  
LVCMOS (Norm/Inv)  
LVDS  
CLKout0 to  
CLKout3 Divider  
CLKoutDIV_0  
CLKoutDIV_1  
÷ 1  
÷ 1  
÷ 1  
÷ 8  
÷ 4  
÷ 4  
÷ 2  
÷ 2  
CLKout4 to  
CLKout7 Divider  
CLKout8 to  
CLKout11 Divider  
÷ 4  
÷ 2  
CLKoutDIV_2  
CLKout12 to  
CLKout13 Divider  
÷ 512  
÷ 16  
TABLE 3. Pin Control Mode for EN_PIN_CTRL = High  
Pin  
Output Groups  
CLKout0 to CLKout3  
CLKout4 to CLkout7  
CLKout8 to CLKout11  
CLKout12 to CLKout13  
Pin=Low  
Pin=Middle  
LVPECL  
Pin=High  
CLKoutTYPE_0  
LVDS  
LVPECL  
LVCMOS (Norm/Inv)  
LVCMOS (Norm/Inv)  
LVCMOS (Norm/Inv)  
CLKoutTYPE_1  
CLKoutTYPE_2  
LVDS  
LVDS  
LVPECL  
LVPECL  
CLKout0 to  
CLKout7 Dividers  
CLKoutDIV_0  
CLKoutDIV_1  
CLKoutDIV_2  
÷ 1  
÷ 1  
÷ 4  
÷ 4  
÷ 4  
÷ 2  
÷ 2  
CLKout8 to  
CLKout11 Divider  
CLKout12 to  
CLKout13 Divider  
÷ 512  
÷ 16  
Note 1: Digital Delay will not work if CLKout12_13_DIV = 1.  
Note 2: See Section 10.0 Electrical Characteristics  
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4
 
 
 
 
 
 
5.0 Connection Diagram  
48-Pin LLP Package  
30148702  
5
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6.0 Pin Descriptions  
(Note 3)  
Pin Number  
Name(s)  
I/O  
Type  
Description  
LEuWire/  
CLKoutDIV_2  
MICROWIRE Latch Enable Input /  
Pin control mode: clock divider 2  
1
I
CMOS / 3-State  
CLKout0  
CLKout0*  
2, 3  
4, 5  
6
O
O
I
Programmable  
Programmable  
PWR  
Clock output 0: LVDS or LVPECL  
Clock output 1: LVDS or LVPECL  
Power supply for clock outputs 0, 1, 2, and 3  
Clock output 2: LVDS or LVPECL  
Clock output 3: LVDS or LVPECL  
CLKout1  
CLKout1*  
Vcc1_CLKout  
0_1_2_3  
CLKout2,  
CLKout2*  
7, 8  
9. 10  
11  
O
O
I
Programmable  
Programmable  
CMOS / 3-State  
CMOS / 3-State  
CLKout3,  
CLKout3*  
Test/  
CLKoutTYPE_0  
Reserved Test Pin /  
Pin control mode: clock output type select 0  
SYNC0/  
CLKoutTYPE_1  
SYNC0 / Pin control mode: clock output type select  
1
12  
I
CLKin0/  
CLKin0*  
Clock input 0. Supports clocking types including but  
not limited to LVDS, LVPECL, and LVCMOS  
13, 14  
15  
I
I
ANLG  
PWR  
Vcc2_CLKin0  
Power supply for clock input 0  
CLKout4/  
CLKout4*  
16, 17  
O
Programmable  
Clock output 4: LVDS, LVPECL, or LVCMOS  
CLKout5*/  
CLKout5  
18, 19  
20  
O
I
Programmable  
PWR  
Clock output 5: LVDS, LVPECL, or LVCMOS  
Power supply for clock outputs 4, 5, 6, and 7  
Clock output 6: LVDS, LVPECL, or LVCMOS  
Clock output 7: LVDS, LVPECL, or LVCMOS  
Vcc3_CLKout  
4_5_6_7  
CLKout6/  
CLKout6*  
21, 22  
23, 24  
O
Programmable  
Programmable  
CLKout7*/  
CLKout7  
O
I
25  
26  
27  
Vcc4_Bias  
Bias  
PWR  
ANLG  
3-State  
Power supply for Bias  
Bias bypass pin  
EN_PIN_CTRL  
I
Select MICROWIRE or pin control mode  
CLKout8/  
CLKout8*  
28, 29  
30, 31  
32  
O
Programmable  
Programmable  
PWR  
Clock output 8: LVDS, LVPECL, or LVCMOS  
Clock output 9: LVDS, LVPECL, or LVCMOS  
Power supply for clock outputs 8, 9, 10, and 11  
Clock output 10: LVDS, LVPECL, or LVCMOS  
CLKout9*/  
CLKout9  
O
I
Vcc5_CLKout  
8_9_10_11  
CLKout10/  
CLKout10*  
33, 34  
O
Programmable  
CLKout11*/  
CLKout11  
35, 36  
37  
O
I
Programmable  
PWR  
Clock output 11: LVDS, LVPECL, or LVCMOS  
Power supply for clock input 1  
Vcc6_CLKin1  
CLKin1/  
CLKin1*  
Clock input 1. Supports clocking types including but  
not limited to LVDS, LVPECL, and LVCMOS  
38, 39  
I
ANLG  
SYNC1/  
CLKoutTYPE_2  
SYNC pin for CLKin1 and bank B.  
Pin control mode: Clock output type select 2  
40  
41  
I
I
CMOS / 3-State  
PWR  
Vcc7_CLKout  
12_13  
Power supply for clock outputs 12, and 13  
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Pin Number  
Name(s)  
I/O  
Type  
Description  
CLKout12/  
CLKout12*  
42, 43  
O
Programmable  
Clock output 12: LVDS, LVPECL, or LVCMOS  
CLKout13*/  
CLKout13  
44, 45  
46  
O
I
Programmable  
PWR  
Clock output 13: LVDS, LVPECL, or LVCMOS  
Power supply for digital  
Vcc8_DIG  
DATAuWire/  
CLKoutDIV_0  
MICROWIRE DATA Pin / Pin control mode: Clock  
divider 0  
47  
I
CMOS / 3-State  
CLKuWire/  
CLKoutDIV_1  
MICROWIRE CLK Pin / Pin control mode: Clock  
divider 1  
48  
I
CMOS / 3-State  
GND  
DAP  
DAP  
DIE ATTACH PAD, connect to GND  
Note 3: See Application Information section Section 17.2 PIN CONNECTION RECOMMENDATIONS for recommended connections.  
7
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7.0 Absolute Maximum Ratings (Note 4, Note 5, Note 6)  
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for  
availability and specifications.  
Parameter  
Symbol  
VCC  
VIN  
Ratings  
-0.3 to 3.6  
-0.3 to (VCC + 0.3)  
-65 to 150  
+260  
Units  
V
Supply Voltage (Note 7)  
Input Voltage  
V
TSTG  
TL  
Storage Temperature Range  
Lead Temperature (solder 4 seconds)  
Differential Input Current (CLKinX/X*)  
Moisture Sensitivty Level  
°C  
°C  
IIN  
± 5  
mA  
MSL  
3
Note 4: "Absolute Maximum Ratings" indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device  
is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.  
The guaranteed specifications apply only to the test conditions listed.  
Note 5: This device is a high performance RF integrated circuit with an ESD rating up to 2.5 kV Human Body Model, up to 250 V Machine Model and up to 1,250  
V Charged Device Model and is ESD sensitive. Handling and assembly of this device should only be done at ESD-free workstations.  
Note 6: Stresses in excess of the absolute maximum ratings can cause permanent or latent damage to the device. These are absolute stress ratings only.  
Functional operation of the device is only implied at these or any other conditions in excess of those given in the operation sections of the data sheet. Exposure  
to absolute maximum ratings for extended periods can adversely affect device reliability.  
Note 7: Never to exceed 3.6 V.  
8.0 Package Thermal Resistance  
48-Lead LLP  
Parameter  
Symbol  
Ratings  
Units  
Thermal resistance from junction to ambient on  
θJA  
26  
°C/W  
4-layer JEDEC board (Note 8)  
Thermal resistance from junction to case  
θJC  
3
°C/W  
(Note 9)  
Note 8: Specification assumes 9 thermal vias connect the die attach pad to the embedded copper plane on the 4-layer JEDEC board. These vias play a key role  
in improving the thermal performance of the LLP. It is recommended that the maximum number of vias be used in the board layout.  
Note 9: Case is defined as the DAP (die attach pad).  
9.0 Recommended Operating Conditions  
Parameter  
Symbol  
TA  
Condition  
Min  
-40  
Typical  
25  
Max  
85  
Unit  
°C  
V
Ambient  
Temperature  
VCC = 3.3 V  
Supply Voltage  
VCC  
TJ  
3.15  
3.3  
3.45  
125  
Junction  
Temperature  
°C  
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8
 
 
 
 
 
 
 
 
 
10.0 Electrical Characteristics  
(3.15 V VCC 3.45 V, -40 °C TA 85 °C. Typical values represent most likely parametric norms at VCC = 3.3 V, TA = 25 °C,  
at the Recommended Operating Conditions at the time of product characterization and are not guaranteed.)  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
Current Consumption  
ICC_PD  
Power Down Supply Current  
1
mA  
mA  
All clock delays disabled,  
CLKoutX_Y_DIV = 1,  
CLKoutX_TYPE = 1 (LVDS),  
Supply Current with all clocks  
ICC_CLKS  
313  
390  
enabled (Note 11)  
CLKin0/0* and CLKin1/1* Input Clock Specifications  
CLKinX_MUX = Bypassed  
0.001  
3100  
1600  
3100  
MHz  
MHz  
MHz  
CLKoutX_Y_DIV = 1  
CLKinX_MUX = Bypassed  
fCLKinX  
Clock 0 or 1 Input Frequency  
.001  
.001  
0.15  
CLKoutX_Y_DIV = 2 to 8  
CLKin_MUX = Divide  
CLKinX_DIV = 1 to 8  
Slew Rate on CLKin  
SLEWCLKin  
DUTYCLKin  
20% to 80%  
0.5  
50  
V/ns  
%
(Note 12)  
Clock input duty cycle  
AC coupled to CLKinX; CLKinX* AC  
coupled to Ground  
(CLKinX_BUF_TYPE = Bipolar  
0.25  
0.25  
2.4  
2.4  
Vpp  
Vpp  
Clock Input,  
Single-ended Input Voltage  
VCLKin  
AC coupled to CLKinX; CLKinX* AC  
coupled to Ground  
(CLKinX_BUF_TYPE = MOS  
VIDCLKin  
VSSCLKin  
VIDCLKin  
VSSCLKin  
0.25  
0.5  
1.55  
3.1  
|V|  
Vpp  
|V|  
AC coupled  
(CLKinX_BUF_TYPE = Bipolar  
Clock Input  
Differential Input Voltage  
(Note 10)  
0.25  
0.5  
1.55  
3.1  
AC coupled  
(CLKinX_BUF_TYPE = MOS  
(Note 18)  
Vpp  
mV  
DC offset voltage between  
CLKinX/CLKinX*  
0
0
Each pin AC coupled  
CLKinX_BUF_TYPE = Bipolar  
VCLKinX-offset  
mV  
V
CLKinX* - CLKinX  
VCLKin- VIH  
VCLKin- VIL  
DC coupled to CLKinX; CLKinX* AC  
coupled to Ground  
VCC  
0.4  
Maximum input voltage  
2.0  
0.0  
Minimum input voltage  
V
CLKinX_BUF_TYPE = MOS  
DC offset voltage between  
CLKinX/CLKinX*  
Each pin AC coupled  
CLKinX_BUF_TYPE = MOS  
VCLKinX-offset  
55  
mV  
CLKinX* - CLKinX  
9
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Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
Digital Inputs (CLKuWire, DATAuWire, LEuWire) for EN_PIN_CTRL = MIDDLE  
VIH  
VIL  
IIH  
VCC  
0.4  
5
High-Level Input Voltage  
Low-Level Input Voltage  
High-Level Input Current  
Low-Level Input Current  
1.2  
V
V
VIH = VCC  
VIL = 0  
-5  
-5  
µA  
µA  
IIL  
5
Digital Inputs (SYNC0, SYNC1) for EN_PIN_CTRL = MIDDLE  
VIH  
VIL  
VCC  
0.4  
High-Level Input Voltage  
1.2  
V
V
Low-Level Input Voltage  
High-Level Input Current  
VIH = VCC  
IIH  
IIL  
VIH = VCC  
VIL = 0  
-5  
5
µA  
µA  
Low-Level Input Current  
VIL = 0 V  
-40  
-5  
Digital Inputs (CLKuWire, DATAuWire, LEuWire, SYNC0, SYNC1) for EN_PIN_CTRL= Low or High  
VIH  
VIM  
VIL  
IIH  
VCC  
1.85  
0.7  
High-Level Input Voltage  
Mid-Level Input Voltage  
Low-Level Input Voltage  
High-Level Input Current  
Mid-Level Input Current  
Low-Level Input Current  
2.6  
1.3  
V
V
V
VIH = VCC  
VIL= 0  
100  
10  
µA  
µA  
µA  
IIM  
-10  
IIL  
-100  
Clock Skew and Delay  
LVDS-to-LVDS, T = 25 °C,  
FCLK = 800 MHz, RL= 100 Ω  
AC coupled, Within same Divider  
LVPECL-to-LVPECL, T = 25 °C  
FCLK = 800 MHz, RL= 100 Ω  
3
3
CLKoutX to CLKoutY  
(Note 13), (Note 14)  
TSKEW  
ps  
emitter resistors = 240 Ω to GND  
AC coupled, Within same Divider  
RL = 50 Ω, CL = 10 pF,  
T = 25 °C, FCLK = 100 MHz, Within  
same Divider  
Skew between any two LVCMOS  
outputs, same CLKout or different  
CLKout (Note 13), (Note 14)  
50  
LVPECL to LVDS skew  
LVDS to LVCMOS skew  
LVCMOS to LVPECL skew  
32  
MixedTSKEW  
CLKoutX -  
CLKoutY  
Same device, T = 25 °C,  
250 MHz, Within same Divider  
830  
800  
ps  
Maximum Analog  
Delay Frequency  
FADLY  
1536  
MHz  
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10  
Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
LVDS Clock Outputs (CLKoutX)  
Maximum Clock Frequency  
fCLKout  
RL = 100 Ω  
1600  
225  
MHz  
mV  
(Note 14, Note 15)  
Differential Output Voltage  
(Note 10)  
VOD  
400  
575  
(Note 18)  
T = 25 °C, DC measurement  
AC coupled to receiver input  
R = 100 Ω differential termination  
Change in Magnitude of VOD for  
complementary output states  
ΔVOD  
VOS  
-50  
50  
1.375  
35  
mV  
V
Output Offset Voltage  
1.125  
1.25  
Change in VOS for complementary  
output states  
ΔVOS  
|mV|  
TR  
TF  
Output Rise Time  
Output Fall Time  
20% to 80%, RL = 100 Ω  
80% to 20%, RL = 100 Ω  
200  
300  
ps  
ps  
ISA  
ISB  
Output short circuit current - single  
ended  
Single-ended output shorted to  
GND, T = 25 °C  
-24  
-12  
24  
12  
mA  
mA  
Output short circuit current -  
differential  
Complimentary outputs tied  
together  
ISAB  
LVPECL Clock Outputs (CLKoutX)  
20% to 80%, RL = 100 Ω,  
emitter resistors = 240 Ω to GND  
80% to 20%, RL = 100 Ω,  
TR  
TF  
Output Rise Time  
Output Fall Time  
200  
200  
ps  
ps  
emitter resistors = 240 Ω to GND  
Low Common-Mode Voltage PECL (LCPECL) (Note 16), (Note 17)  
RL = 100 Ω,  
emitter resistors = 240 Ω to GND  
Maximum Clock Frequency  
fCLKout  
3100  
MHz  
(Note 14, Note 15)  
VOH  
VOL  
VOD  
Output High Voltage  
Output Low Voltage  
Output Voltage  
1.6  
0.75  
840  
V
V
T = 25 °C, DC Measurement  
Termination = 50 Ω to  
VCC - 0.6 V  
535  
1145  
1240  
1585  
mV  
1600 mV LVPECL (LVPECL) Clock Outputs (CLKoutX)  
RL = 100 Ω,  
emitter resistors = 240 Ω to GND  
Maximum Clock Frequency  
fCLKout  
3100  
MHz  
(Note 14, Note 15)  
VOH  
VOL  
VOD  
VCC - 0.94  
VCC - 1.9  
925  
Output High Voltage  
Output Low Voltage  
Output Voltage  
V
V
T = 25 °C, DC Measurement  
Termination = 50 Ω to  
VCC - 2.0 V  
585  
mV  
2000 mV LVPECL (2VPECL) Clock Outputs (CLKoutX)  
RL = 100 Ω,  
emitter resistors = 240 Ω to GND  
Maximum Clock Frequency  
fCLKout  
3100  
MHz  
(Note 14, Note 15)  
VOH  
VOL  
VOD  
VCC - 0.97  
VCC - 1.95  
1150  
Output High Voltage  
Output Low Voltage  
Output Voltage  
V
V
T = 25 °C, DC Measurement  
Termination = 50 Ω to  
VCC - 2.3 V  
705  
mV  
11  
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Symbol  
Parameter  
Conditions  
Min  
Typ  
Max  
Units  
LVCMOS Clock Outputs (CLKoutX)  
Maximum Clock Frequency  
fCLKout  
5 pF Load  
250  
MHz  
(Note 14, Note 15)  
VOH  
VOL  
IOH  
IOL  
VCC - 0.1  
Output High Voltage  
Output Low Voltage  
1 mA Load  
1 mA Load  
V
V
0.1  
55  
VCC = 3.3 V, VO = 1.65 V  
VCC = 3.3 V, VO = 1.65 V  
Output High Current (Source)  
Output Low Current (Sink)  
28  
28  
mA  
mA  
VCC/2 to VCC/2, FCLK = 100 MHz, T  
= 25 °C  
Output Duty Cycle  
DUTYCLK  
45  
50  
%
ps  
ps  
(Note 14)  
20% to 80%, RL = 50 Ω,  
TR  
TF  
Output Rise Time  
Output Fall Time  
400  
400  
CL = 5 pF  
80% to 20%, RL = 50 Ω,  
CL = 5 pF  
MICROWIRE Interface Timing  
See MICROWIRE Input Timing  
See MICROWIRE Input Timing  
See MICROWIRE Input Timing  
See MICROWIRE Input Timing  
See MICROWIRE Input Timing  
See MICROWIRE Input Timing  
See MICROWIRE Input Timing  
TECS  
TDCS  
TCDH  
TCWH  
TCWL  
TCES  
TEWH  
LE to Clock Set Up Time  
Data to Clock Set Up Time  
Clock to Data Hold Time  
Clock Pulse Width High  
Clock Pulse Width Low  
Clock to LE Set Up Time  
LE Pulse Width  
25  
25  
8
ns  
ns  
ns  
ns  
ns  
ns  
ns  
25  
25  
25  
25  
See MICROWIRE Readback  
Timing  
TCR  
Falling Clock to Readback Time  
25  
ns  
Note 10: See applications section Section 13.1 DIFFERENTIAL VOLTAGE MEASUREMENT TERMINOLOGY for definition of VID and VOD voltages.  
Note 11: For Icc for specific part configuration, see applications section Section 17.1.1 Current Consumption for calculating Icc.  
Note 12: The minimum recommended slew rate for all input clocks is 0.5 V/ns. This is especially true for single-ended clocks. Phase noise performance will begin  
to degrade as the clock input slew rate is reduced. However, the device will function at slew rates down to the minimum listed. When compared to single-ended  
clocks, differential clocks (LVDS, LVPECL) will be less susceptible to degradation in phase noise performance at lower slew rates due to their common mode  
noise rejection. However, it is also recommended to use the highest possible slew rate for differential clocks to achieve optimal phase noise performance at the  
device outputs.  
Note 13: Equal loading and identical clock output configuration on each clock output is required for specification to be valid. Specification not valid for delay mode.  
Note 14: Guaranteed by characterization.  
Note 15: Refer to typical performance charts for output operation performance at higher frequencies than the minimum maximum output frequency.  
Note 16: For LCPECL, the common mode voltage is regulated (VOH=1.6V, VOL=VOH-Vsw, Vcm=(VOH+VOL)/2 ) and is more stable against with PVT (process,  
supply, temperature) variations than conventional LVPECL implementations..  
Note 17: With proper selection of external emitter resistors, LCPECL can also be used for DC-coupling with devices with low common voltage such as 0.5V or  
0,8V etc.  
Note 18: Refer to application note AN-912 Common Data Transmission Parameters and their Definitions for more information.  
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12  
 
 
 
 
 
 
 
 
 
11.0 Typical Performance  
Characteristics  
Unless otherwise specified: Vdd=3.3V, TA=25 °C  
LVDS VSS vs. Frequency (Note 19)  
LVPECL VSS vs. Frequency (Note 19)  
1.0  
2.0  
LVPECL 2V Mode  
0.8  
0.6  
0.4  
0.2  
0.0  
1.5  
LVPECL 1.6V Mode  
1.0  
LCPECL Mode  
0.5  
0.0  
0
400  
800  
1200 1600 2000  
0
500 1000 1500 2000 2500 3000  
FREQUENCY (MHz)  
FREQUENCY (MHz)  
30148779  
30148776  
LVCMOS Vpp vs. Frequency  
Typical Dynamic ICC, CL = 5 pF  
4.0  
80  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0.0  
5 pF Load  
60  
40  
20  
0
10 pF Load  
22 pF Load  
0
100  
200  
300  
400  
500  
0
50 100 150 200 250 300 350 400  
FREQUENCY (MHz)  
FREQUENCY (MHz)  
30148778  
30148777  
LVPECL Noise Floor vs. Frequency  
LVDS & LVCMOS Noise Floor vs. Frequency  
-140  
-145  
-145  
-150  
LVPECL (differential)  
LVDS (differential)  
-155  
-150  
-155  
-160  
-165  
-170  
-175  
-180  
Re=240 Ω  
-160  
-165  
-170  
LVCMOS  
LVPECL (differential)  
Re=120 Ω  
-175  
-180  
10  
100  
1k  
10k  
10  
100  
1k  
10k  
FREQUENCY (MHz)  
FREQUENCY (MHz)  
30148780  
30148781  
13  
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Note 19: See Section 13.1 DIFFERENTIAL VOLTAGE MEASUREMENT TERMINOLOGY for a description of VSS  
.
12.0 Serial MICROWIRE Timing Diagram  
30148703  
FIGURE 1. MICROWIRE Timing Diagram  
Register programming information on the DATAuWire pin is clocked into a shift register on each rising edge of the CLKuWire signal.  
On the rising edge of the LEuWire signal, the register is sent from the shift register to the register addressed. A slew rate of at least  
30 V/µs is recommended for these signals. After programming is complete the CLKuWire, DATAuWire, and LEuWire signals should  
be returned to a low state.  
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13.0 Measurement Definitions  
13.1 DIFFERENTIAL VOLTAGE MEASUREMENT TERMINOLOGY  
The differential voltage of a differential signal can be described by two different definitions causing confusion when reading  
datasheets or communicating with other engineers. This section will address the measurement and description of a differential  
signal so that the reader will be able to understand and discern between the two different definitions when used.  
The first definition used to describe a differential signal is the absolute value of the voltage potential between the inverting and  
non-inverting signal. The symbol for this first measurement is typically VID or VOD depending on if an input or output voltage is being  
described.  
The second definition used to describe a differential signal is to measure the potential of the non-inverting signal with respect to  
the inverting signal. The symbol for this second measurement is VSS and is a calculated parameter. Nowhere in the IC does this  
signal exist with respect to ground, it only exists in reference to its differential pair. VSS can be measured directly by oscilloscopes  
with floating references, otherwise this value can be calculated as twice the value of VOD as described in the first section  
Figure 2 illustrates the two different definitions side-by-side for inputs and Figure 3 illustrates the two different definitions side-by-  
side for outputs. The VID and VOD definitions show VA and VB DC levels that the non-inverting and inverting signals toggle between  
with respect to ground. VSS input and output definitions show that if the inverting signal is considered the voltage potential reference,  
the non-inverting signal voltage potential is now increasing and decreasing above and below the non-inverting reference. Thus the  
peak-to-peak voltage of the differential signal can be measured.  
VID and VOD are often defined in volts (V) and VSS is often defined as volts peak-to-peak (VPP).  
30148775  
30148774  
FIGURE 2. Two Different Definitions for  
Differential Input Signals  
FIGURE 3. Two Different Definitions for  
Differential Output Signals  
15  
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When adjusting analog delay, glitches may occur on the clock  
outputs being adjusted.  
14.0 Features  
14.1 SYSTEM ARCHITECTURE  
14.7 CLKout12 & CLKout13 DIGITAL DELAY  
The LMK01801 is a dual clock buffer which allows separate  
clock domains on the same IC with options to divide and delay  
signals.  
CLKout12 and CLKout13 includes a coarse (digital) delay for  
phase adjustment of the clock outputs.  
The coarse (digital) delay allows a group of outputs to be de-  
layed by 4.5 to 12 clock distribution path cycles in normal  
mode, or from 12.5 to 522 clock cycles in extended mode. The  
delay step can be as small as half the period of the clock dis-  
tribution path by using the CLKout12_13_HS bit. e.g. 2 GHz  
clock frequency without using CLKin1 input clock divider re-  
sults in 250 ps coarse tuning steps.  
The LMK01801 consists of two separate buffer banks, each  
with its own input divider, output dividers and programmable  
control of clock output channels.  
Bank A has two clock output groups, see the Section 4.0  
Functional Configurations for more details.  
Bank B has two clock output groups, one of which has  
analog and digital delay. See the Section 4.0 Functional  
Configurations for more details.  
The coarse (digital) delay value takes effect on the clock out-  
puts after a SYNC event.  
Each bank has it own common input divider and is then di-  
vided into output groups which share an output divider.  
There are 2 different ways to use the digital (coarse) delay.  
1. Fixed Digital Delay  
The LMK01801 comes in a 48-pin LLP package.  
2. Relative Dynamic Digital Delay  
These are further discussed in the Functional Description.  
14.2 HIGH SPEED CLOCK INPUTS (CLKin0/CLKin0* and  
CLKin1/CLKin1*)  
14.8 PROGRAMMABLE OUTPUTS  
The LMK01801 has two clock inputs, CLKin0 and CLKin1  
which can be driven differentially or single-ended. See Sec-  
tion 17.4 DRIVING CLKin INPUTS for more information. Each  
input has a 2 to 8 divider that may be enabled or bypassed.  
The outputs of the LMK01801 are programmable in a combi-  
nation of output types based on Table 1. Programming the  
outputs is by MICROWIRE or by pin control mode based on  
the state of EN_PIN_CTRL pin.  
14.3 CLOCK DISTRIBUTION  
Any LVPECL output type can be programmed to LCPECL,  
1600, or 2000 mVpp amplitude levels. The 2000 mVpp  
LVPECL output type is a Texas Instruments proprietary con-  
figuration that produces a 2000 mVpp differential swing for  
compatibility with many data converters and is also known as  
2VPECL.  
The LMK01801 features a total of 14 differential outputs.  
CLKout0 through CLKout7 are driven from CLKin0 and CLK-  
out8 through CLKout13 are driven from CLKin1.  
14.4 SMALL DIVIDER (1 to 8)  
There are three small dividers which drive CLKout0 to CLK-  
out3, CLKout4 to CLKout7, and CLKout8 to CLKout 11. These  
dividers support a divide range of 1 to 8 (even and odd).  
14.9 CLOCK OUTPUT SYNCHRONIZATION  
Using the SYNC input causes all active clock outputs to share  
a rising edge. See Section 15.6 CLOCK OUTPUT SYN-  
CHRONIZATION (SYNC) for more information.  
14.5 LARGE DIVIDER (1 to 1045 )  
The divider for CLKout12 and CLKout13 supports a divide  
range of 1 to 1045 (even and odd). When divides of 26 or  
greater are used, the divider/delay block uses extended  
mode.  
The SYNC event also causes the digital delay value to take  
effect.  
14.10 DEFAULT CLOCK OUTPUTS  
The power on reset sets the device to operate with all outputs  
active in bypass mode (no divide) with LVDS output type. In  
this way the device can be used without programming for fan-  
out purposes.  
14.6 CLKout ANALOG DELAY  
Clock outputs 12 and 13 include a fine (analog) delay for  
phase adjustment of the clock outputs.  
The fine (analog) delay allows a nominal 25 ps step size and  
range from 0 to 475 ps of total delay. Enabling the analog  
delay adds a nominal 500 ps of delay in addition to the pro-  
grammed value.  
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16  
 
 
 
 
 
 
 
 
 
 
 
TABLE 4. Possible Digital Delay Values  
15.0 Functional Description  
CLKout12_13_DDL CLKout12_13_HS Digital Delay  
Y
15.1 PROGRAMMABLE MODE  
When the EN_PIN_CTRL pin is floating (default by internal  
pull-up/pull-down) then programming is via MICROWIRE.  
5
5
1
0
1
0
1
0
...  
0
1
0
1
0
4.5  
5
See Table 1 for a description of available programming op-  
tions for the LMK01801 in programmable mode.  
6
5.5  
6
6
15.2 PIN CONTROL MODE  
7
6.5  
7
The LMK01801 provides for an alternate function of the MI-  
CROWIRE (uWire) pins. This pin control mode is set by the  
logic of the EN_PIN_CTRL pin to provide limited control of the  
outputs and dividers.  
7
...  
...  
520  
521  
521  
522  
522  
520  
520.5  
521  
521.5  
522  
When the EN_PIN_CTRL pin is set high or low (not open) then  
the output states can be programmed by pins, eliminating the  
need for an external FPGA or CPU.  
If EN_PIN_CTRL is LOW then Table 2 in Section 4.0 Func-  
tional Configurations defines how the outputs and dividers are  
configured.  
The CLKout12_13_DDLY value only takes effect during a  
SYNC event and if the NO_SYNC_CLKout12_13 bit is  
cleared for this clock group. See Section 15.6 CLOCK OUT-  
PUT SYNCHRONIZATION (SYNC) for more information.  
If EN_PIN_CTRL is HIGH then Table 3 in Section 4.0 Func-  
tional Configurations defines how the outputs and dividers are  
configured.  
15.3 INPUTS / OUTPUTS  
15.3.1 CLKin0 and CLKin1  
The resolution of digital delay is related to the frequency at  
the input to the Clock Group 4 (CG4) clock distribution path.  
Digital Delay Resolution = 1 / (2 * Clock Frequency)  
There are two clock inputs CLKin0 and CLKin1. CLKin0 pro-  
vides the input for output Bank A and CLKin1 provides the  
input for the output Bank B. Each input has it's own divider (2  
to 8) that may be bypassed.  
The digital delay between clock outputs can be dynamically  
adjusted with minimum or no disruption of the output clocks.  
See Section 15.6.1 Dynamically Programming Digital Delay  
for more information.  
15.4 INPUT AND OUTPUT DIVIDERS  
15.5.1 Fixed Digital Delay - Example  
This section discusses the recommended usage of input and  
output dividers.  
Given a CLKin1 clock frequency of 983.04 MHz as input to  
CG4, by using digital delay the outputs can be adjusted in 1 /  
(2 * 983.04 MHz) = ~509 ps steps (Assumes CLKin1_MUX =  
bypass).  
Clock inputs 0 and 1 each have an associated divider (2 to 8)  
that may be enabled or bypassed.  
Clock groups 1, 2 and 3 have small output dividers (1 to 8).  
Clock group 4 (CLKout12 and CLKout13) has a large output  
divider (1 to 1045).  
To achieve a quadrature (90 degree) phase shift on 122.88  
MHz outputs between CLKout12 and CLKout11 from a clock  
frequency of 983.04 MHz program:  
While the input and output clock dividers may be used in any  
combination the recommended operating frequency ranges  
are shown in the table below to minimize the phase noise  
floor:  
Clock output divider to 8. CLKout8_11 = 8 and  
CLKout12_13_DIV = 8  
Set clock digital delay value. CLKout12_13_DDLY = 5,  
CLKout12_13_HS = 0.  
Input and Output Divider Input Frequency Ranges  
The frequency of 122.88 MHz has a period of ~8.14 ns. To  
delay 90 degrees of a 122.88 MHz clock period requires a  
~2.03 ns delay. Given a digital delay step of ~509 ps, this  
requires a digital delay value of 4 steps (2.03 ns / 509 ps = 4).  
Since the 4 steps are half period steps, CLKout12_13_DDLY  
is programmed 2 full periods beyond 5 for a total of 7.  
Input Divider  
Bypassed  
Output Divider  
Divide = 1  
Max Frequency  
3.1 GHz  
Bypassed  
Divide > 1  
1.6 GHz  
Divide = 2 to 8  
Divide = 1 to 8  
3.1 GHz  
Table 5 shows some of the possible phase delays in degrees  
15.5 FIXED DIGITAL DELAY  
achievable in the above example.  
This section discusses Fixed Digital Delay and associated  
registers.  
TABLE 5. Relative phase shift from  
CLKout12 and CLKout13 to CLKout8 to CLKout11  
Clock outputs 12 and 13 may be delayed relative to CLKout8  
to CLKout 11 by up to 517.5 clock distribution path periods if  
divide is 1 and 518.5 clock distribution path periods if divide  
is greater than 1. By programming a digital delay value from  
4.5 to 522 clock distribution path periods, a relative clock out-  
put delay from 0 to 517.5 periods is achieved. The  
CLKout12_13_DDLY register sets the digital delay as shown  
in the table Table 4.  
Relative  
Digital  
Delay  
CLKout12_ CLKout12_  
Degrees of  
122.88 MHz  
13_DDLY  
13_HS  
5
5
6
6
7
1
0
1
0
1
-0.5  
0.0  
0.5  
1.0  
1.5  
-23°  
0°  
23°  
45°  
68°  
17  
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Refer to Section 15.6.1 Dynamically Programming Digital De-  
lay for SYNC functionality when SYNC_QUAL = 1.  
Relative  
Digital  
Delay  
CLKout12_ CLKout12_  
Degrees of  
122.88 MHz  
13_DDLY  
13_HS  
TABLE 6. Steady State Clock Output Condition  
Given Specified Inputs  
7
8
0
1
0
1
0
1
0
1
0
1
0
1
0
...  
2.0  
2.5  
3.0  
3.5  
4.0  
4.5  
5.0  
5.5  
6.0  
6.5  
7.0  
7.5  
8.0  
...  
90°  
113°  
135°  
158°  
180°  
203°  
225°  
248°  
270°  
293°  
315°  
338°  
360°  
...  
SYNC_POL  
_INV  
Clock Steady  
State  
SYNC Pin  
8
0
0
1
1
0
1
0
1
Active  
Low  
9
9
Low  
10  
10  
11  
11  
12  
12  
13  
13  
...  
Active  
Methods of Generating SYNC  
There are three methods to generate a SYNC event:  
Manual:  
Asserting the SYNC pin according to the polarity set by  
SYNC_POL_INV.  
Toggling the SYNC_POL_INV bit though MICROWIRE  
will cause a SYNC to be asserted.  
Automatic:  
Programming Register R4 when SYNC_EN_AUTO =  
1 will generate a SYNC event for Bank B.  
Programming Register R5 when SYNC_EN_AUTO =  
1 will generate a SYNC event for both Bank A and Bank  
B.  
Figure 5 illustrates clock outputs programmed with different  
digital delay values during a SYNC event.  
Refer to Section 15.6.1 Dynamically Programming Digital De-  
lay for more information on dynamically adjusting digital de-  
lay.  
Due to the high speed of the clock distribution path (as fast  
as ~322 ps period) and the slow slew rate of the SYNC, the  
exact clock cycle at which the SYNC is asserted or unassert-  
ed by the SYNC is undefined. The timing diagrams show a  
sharp transition of the SYNC to clarify functionality.  
15.6 CLOCK OUTPUT SYNCHRONIZATION (SYNC)  
The purpose of the SYNC function is to synchronize the clock  
outputs with a fixed and known phase relationship between  
each clock output selected for SYNC. SYNC can also be used  
to hold the outputs in  
a
low or  
0
state. The  
Avoiding clock output interruption due to SYNC  
NO_SYNC_CLKoutX_Y bits can be set to disable synchro-  
nization for a clock group.  
If a clock output has the NO_SYNC_CLKoutX_Y bits set they  
will be unaffected by the SYNC event. It is possible to perform  
a SYNC operation with the NO_SYNC_CLKoutX_Y bit  
cleared, set the NO_SYNC_CLKoutX_Y bits so that the se-  
lected clocks will not be affected by a future SYNC. Future  
SYNC events will not effect these clocks but will still cause  
the newly synchronized clocks to be resynchronized using the  
currently programmed digital delay values. When this hap-  
pens, the phase relationship between the first group of syn-  
chronized clocks and the second group of synchronized  
clocks will be undefined. Except for CLKout12 and CLKout13  
when synced using qualification mode. See Section 15.6.1  
Dynamically Programming Digital Delay.  
The digital delay value set by CLKout12_13_DDLY takes ef-  
fect only upon a SYNC event. The digital delay due to  
CLKout12_13_HS takes effect immediately upon program-  
ming. See Section 15.6.1 Dynamically Programming Digital  
Delay for more information on dynamically changing digital  
delay.  
It is necessary to ensure that the CLKin1 signal is stable be-  
fore a sync event occurs when CLKout12_13_DIV is greater  
than 1.  
Effect of SYNC  
When SYNC is asserted, the outputs to be synchronized are  
held in a logic low state. When SYNC is unasserted, the clock  
outputs to be synchronized are activated and will transition to  
a high state simultaneously with one another except where  
digital delay values have been programmed.  
SYNC Timing  
When discussing the timing of the SYNC function, one cycle  
refers to one period of the clock distribution path.  
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18  
 
30148704  
FIGURE 4. Clock Output synchronization using the SYNC1 pin (SYNC1 is Active Low, SYNC1_POL_INV=0)  
CLKout8_11_DIV = 1  
CLKout12_13_DIV = 2  
The digital delay for clock outputs 12 and 13 is 5  
The digital delay half step for all clock outputs is 0  
SYNC1_QUAL = 0 (No qualification)  
CLKout12_ADLY_SEL & CLKout13_ADLY_SEL is 0  
Refer to Figure 4 during this discussion on the timing of  
After SYNC becomes unasserted the event will be registered  
on the following rising edge of the distribution path clock, time  
D. Clock outputs 0 through 11 will rise at time E, coincident  
with a rising distribution clock edge that occurs after 5 cycles  
for CLKout0 to CLKout 11 and for CLKout12 to CLKout13 if  
CLKout12_13_DIV = 1. If CLKout12_13_DIV > 1 then the ris-  
ing edge of CLKout12-CLKout13 will occur after 6 cycles of  
the distribution path at time F plus as many more cycles as  
programmed by the digital delay for that clock output path.  
The CLKout12 and CLKout13 will rise at time G, which is the  
Digital Delay value plus 5 cycles when CLKout12_13_DIV =  
1 or 6 cycles when CLKout12_13_DIV > 1.  
SYNC. SYNC must be asserted for greater than one clock  
cycle of the clock distribution path to register the SYNC event.  
After SYNC is asserted the SYNC event will begin on the fol-  
lowing rising edge of the distribution path clock, at time A.  
After this event has been registered, the outputs will not reflect  
the low state for 4.5 cycles for CLKout0 - CLKout11 at time B  
or 5.5 cycles for CLKout12 and CLKout 13 if divide = 1 or 6.5  
cycles for CLKout12 and CLKout13 if divide > 1, at time C.  
Due to the asynchronous nature of SYNC with respect to the  
output clocks, it is possible that a runt pulse could be created  
when the clock output goes low from the SYNC event. This is  
shown by CLKout12-13. See Section 15.6.1.2 RELATIVE  
DYNAMIC DIGITAL DELAY - EXAMPLE for more information  
on synchronizing relative to an output clock to eliminate or  
minimize this runt pulse for CLKout12 or CLKout13.  
See Figure 5 for further SYNC timing detail using different  
digital delays.  
19  
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30148705  
FIGURE 5. Clock Output synchronization using the SYNC pin (SYNC is Active Low, SYNC_POL_INV=1)  
Case 1: CLKout12_13_DIV = 2, CLKout12_13_DDLY = 5  
Case 2: CLKout12_13_DIV = 2, CLKout12_13_DDLY = 7  
Case 3: CLKout12_13_DIV = 2, CLKout12_13_DDLY = 8  
Case 1: CLKout12_13_HS = 1  
Case 2: CLKout12_13_HS = 0  
Case 3: CLKout12_13_HS = 0  
SYNC1_QUAL = 0 (No qualification)  
CLKout12_ADLY_SEL & CLKout13_ADLY_SEL is 0  
Figure 5 illustrates the timing with various digital delays pro-  
grammed.  
same, then a relative dynamic digital delay adjust is per-  
formed. Clocks with NO_SYNC_CLKoutX_Y = 1 are defined  
as clocks not being adjusted. These clocks operate without  
interruption.  
Time A) SYNC assertion event is registered.  
Time B) SYNC unassertion registered.  
Time C) All outputs toggle and remain low. A runt pulse  
can occur at this time as shown.  
SYNC and Minimum Step Size  
The minimum step size adjustment for digital delay is half a  
clock distribution path cycle. This is achieved by using the  
CLKout12_13_HS bit. The CLKout12_13_HS bit change ef-  
fect is immediate without the need for SYNC. To shift digital  
delay using CLKout12_13_DDLY, a SYNC signal must be  
generated for the change to take effect.  
Time D) After 6 + 4.5 = 10.5 cycles, in Case 1, CLKout12  
rises.  
Time E) After 6 + 7 = 13 cycles, in Case 2, CLKout12 rises.  
Time F) After 6 + 8 = 14 cycles, Case 3, CLKout12 rises.  
Note: CLKout 12 and CLKout 13 are driven by the same  
divider and delay circuit, therefore, their timing is always  
the same except when analog delay is used.  
Programming Overview  
To dynamically adjust the digital delay with respect to an ex-  
isting clock output the device should be programmed as  
follows:  
15.6.1 Dynamically Programming Digital Delay  
To use dynamic digital delay synchronization qualifica-  
tion set SYNC1_QUAL = 3. This causes the SYNC pulse to  
be qualified by a clock output so that the SYNC event occurs  
after a specified time from a clock output transition. This al-  
lows the relative adjustment of clock output phase in real-time  
with no or minimum interruption of clock outputs. Hence the  
term dynamic digital delay.  
Set SYNC1_QUAL = 3 for clock output qualification.  
Set NO_SYNC_CLKout12_13 = 0 to enable  
synchronization on CLKout12 and CLKout13.  
Set CLKout12_ADLY_SEL = 0.  
Set NO_SYNC_CLKoutX_Y = 1 for the output clocks,  
except CLKout12 and CLKout13, that will continue to  
operate during the SYNC event. There is no interruption  
of output on these clocks.  
The SYNC_EN_AUTO bit may be set to cause a SYNC  
event to begin when register R4 is programmed. The auto  
SYNC feature is a convenience since it does not require  
the application to manually assert SYNC by toggling the  
SYNC_POL_INV bit or the SYNC pin when changing  
digital delay.  
Note that changing the phase of a clock output requires mo-  
mentarily altering in the rate of change of the clock output  
phase and therefore by definition results in a frequency dis-  
tortion of the signal.  
Without qualifying the SYNC with an output clock, the newly  
synchronized clocks would have a random and unknown dig-  
ital delay (or phase) with respect to clock outputs not currently  
being synchronized. Only CLKout12 can be used as a quali-  
fying clock.  
Internal Dynamic Digital Delay Timing  
Once SYNC is qualified by an output clock, 1.5 cycles later  
an internal one shot pulse will occur. The width of the one shot  
pulse is 3 cycles. This internal one shot pulse will cause the  
Relative Dynamic Digital Delay  
When the qualifying clock digital delay is being adjusted, be-  
cause the qualifying clock and the adjusted clock are the  
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outputs to turn off and then back on with a fixed delay with  
respect to the falling edge of the qualification clock. This al-  
lows for dynamic adjustments of digital delay with respect to  
an output clock.  
programming register R5. The timing of this is as shown in  
Figure 4.  
Step 2: Now the registers will be programmed to prepare for  
changing digital delay (or phase) dynamically.  
The qualified SYNC timing is shown in Figure 6 for relative  
dynamic digital delay.  
Register  
Purpose  
Use clock output for  
qualifying the SYNC pulse for  
dynamically adjusting digital  
delay.  
Dynamic Digital Delay Conditions  
To perform a dynamic digital delay adjustment, the analog  
delay must be bypassed by setting CLKout12_ADLY_SEL to  
0. If the analog delay is not bypassed the output synchro-  
nization may be inaccurate due to unknown analog delay  
settings.  
SYNC1_QUAL = 3  
Clock output 8 (983.04 MHz)  
won't be affected by SYNC. It  
will operate without  
NO_SYNC_CLKout7_11 = 1  
SYNC1_AUTO = 0 (default)  
When adjusting digital delay dynamically, the falling edge of  
the qualifying clock must coincide with the falling edge of the  
clock distribution path. For this requirement to be met, pro-  
gram the CLKout12_13_HS value of the qualifying clock  
group according to Table 7.  
interruption.  
Automatically generation of  
SYNC is not allowed  
because of the half step  
requirement.  
SYNC must be generated  
manually by toggling the  
SYNC_POL_INV bit or the  
SYNC pin.  
TABLE 7. Half Step programming requirement of  
qualifying clock during SYNC event  
CLKout12_13_DIV value  
CLKout12_13_HS  
Odd  
Must = 1 during SYNC event.  
Must = 0 during SYNC event.  
Even  
After the above registers have been programmed, the appli-  
cation may now dynamically adjust the digital delay of the  
491.52 MHz clocks.  
15.6.1.1 RELATIVE DYNAMIC DIGITAL DELAY  
Relative dynamic digital delay can be used to program a clock  
output to a specific phase offset from another clock output.  
Step 3: Adjust digital delay of CLKout12 by one step.  
Refer to Table 8 for the programming sequence to step one  
half clock distribution period forward or backwards.  
Pros:  
Direct phase adjustment with respect to same clock  
output.  
TABLE 8. Programming sequence for one step adjust  
Possible glitch pulses from clock output will always be the  
same during digital delay adjustment transient.  
Step direction and current Programming Sequence  
HS state  
Cons:  
Adjust clock output one step 1. CLKout12_13_HS = 1.  
forward.  
For some clock divide values there may be a glitch pulse  
due to SYNC assertion.  
CLKout12_13_HS = 0.  
Adjustments of digital delay requiring the half step bit  
(CLKout12_13_HS) for finer digital delay adjust is  
complicated due to the half step requirement in Table 7  
above.  
Adjust clock output one step 1. CLKout12_13_DDLY = 9.  
forward.  
CLKout12_13_HS = 1.  
2. Perform SYNC event.  
3. CLKout12_13_HS = 0.  
15.6.1.2 RELATIVE DYNAMIC DIGITAL DELAY -  
EXAMPLE  
Adjust clock output one step 1. CLKout12_13_HS = 1.  
backward.  
CLKout12_13_HS = 0.  
2. CLKout12_13_DDLY = 5.  
3. Perform SYNC event.  
To illustrate the relative dynamic digital delay adjust proce-  
dure, consider the following example.  
Adjust clock output one step 1. CLKout12_13_HS = 0.  
backward.  
CLKout12_13_HS = 1.  
System Requirements:  
CLKin1 Frequency = 983.04 MHz  
CLKout8 = 983.04 MHz (CLKout8_11_DIV = 1)  
CLKout12 = 491.52 MHz (CLKout12_13_DIV = 2)  
During initial programming:  
To fulfill the qualifying clock output half step requirement in  
Table 7 when dynamically adjusting digital delay, the  
CLKout12_13_HS bit must be set if CLKout12 or CLKout13  
has an odd divide. So before any dynamic digital delay ad-  
justment, CLKout12_13_HS must be set because the clock  
divide value is odd. To achieve the final required digital delay  
adjustment, the CLKout12_13_HS bit may cleared after  
SYNC.  
CLKout12_13_DDLY = 5  
CLKout12_13_HS = 0  
NO_SYNC_CLKoutX_Y = 0  
The application requires the 491.52 MHz clock to be stepped  
in 90 degree steps (~508.6 ps), which is the minimum step  
resolution allowable by the clock distribution path. That is 1 /  
983.04 MHz / 2 = ~169.5 ps. During the stepping of the 491.52  
MHz clocks the 983.04 MHz clock must not be interrupted.  
If a SYNC is to be generated this can be done by toggling the  
SYNC pin or by toggling the SYNC_POL_INV bit. Because of  
the internal one shot pulse, no strict timing of the SYNC pin  
or SYNC_POL_INV bit is required. After the SYNC event, the  
clock output will be at the specified phase. See Figure 6 for a  
detailed view of the timing diagram. The timing diagram criti-  
cal points are:  
Step 1: The device is programmed from register R0 to R5 with  
values that result in the device operating as desired, see the  
system requirements above. The phase of all the output  
clocks are aligned because all the digital delay and half step  
values were the same when the SYNC was generated by  
Time A) SYNC assertion event is registered.  
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Time B) First qualifying falling clock output edge.  
Time C) Second qualifying falling clock output edge.  
Time D) Internal one shot pulse begins. 5.5 cycles later  
CLKout12 outputs will be forced low while 8.5 cycles later  
CLKout8 outputs will be forced low.  
Time E) Internal one shot pulse ends. 6 cycles + digital  
delay cycles later CLKout12 or CLKout13 outputs rise. 10  
cycles later CLKout8 to CLKout11 outputs rise.  
Time F) CLKout12 to CLKout13 outputs are forced low.  
Time G) Beginning of digital delay cycles.  
Time H) CLKout8 to CLKout11 outputs are forced low.  
Time I) CLKout8 to CLKout11 outputs rise now.  
Time j) For CLKout12_13_DDLY = 5; the CLKout12 and  
CLKout13 outputs rise now.  
30148755  
FIGURE 6. Relative Dynamic Digital Delay Programming Example, 2nd adjust. (SYNC1_QUAL = 1, Qualify with clock  
output)  
Starting condition is after half step is removed (CLKout12_13_HS = 0).  
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R0 with the reset bit (b4) set to 1 to ensure the device is in a  
default state. Then R0 is programmed again, the reset bit is  
be cleared to 0 during the re-programming of R0.  
16.0 General Programming  
Information  
LMK01801 devices are programmed using 32-bit registers.  
Each register consists of a 4-bit address field and 23-bit data  
field. The address field is formed by bits 0 through 3 (LSBs)  
and the data field is formed by bits 4 through 31 (MSBs). The  
contents of each register is clocked in MSB first (bit 31), and  
the LSB (bit 0) last. During programming, the LE signal should  
be held LOW. The serial data is clocked in on the rising edge  
of the CLK signal. After the LSB (bit 0) is clocked in the LE  
signal should be toggled LOW-to-HIGH-to-LOW to latch the  
contents into the register selected in the address field. It is  
recommended to program registers in numeric order, for ex-  
ample R0 to R5 and R15 to achieve proper device operation.  
Figure 1 illustrates the serial data timing sequence.  
16.1.1 Overview  
R0 (Init):  
Program R0 with RESET = 1. This ensures that the  
device is configured with default settings. When  
RESET =1, all other R0 bits are ignored.  
R0: Powerdown Controls and CLKin Dividers  
Program R0 with RESET = 0  
R1 and R2: Clock output types  
R3: SYNC Features and Analog Delay for CLKout12 and  
CLKout13  
R4: Dynamic Digital Delay for CLKout12 and CLKout13  
R5: CLKout Dividers and Analog Delay Select  
R15: uWireLock  
16.1 RECOMMENDED PROGRAMMING SEQUENCE  
Registers are programmed in numeric order with R0 being the  
first and R15 being the last register programmed. The rec-  
ommended programming sequence involves programming  
16.2 REGISTER MAP  
Table 9 provides the register map for device programming:  
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RESET  
uWireLock  
POWERDOWN  
CLKout0_3_PD  
CLKout4_7_PD  
CLKout8_11_PD  
CLKout12_13_PD  
CLKin0_BUF_TYPE  
CLKin1_BUF_TYPE  
CLKout12_13_HS  
SYNC1_QUAL  
CLKout12_ADLY_SEL  
CLKout13_ADLY_SEL  
SYNC0_POL_INV  
SYNC1_POL_INV  
NO_SYNC_CLKout0_3  
NO_SYNC_CLKout4_7  
NO_SYNC_CLKout8_11  
NO_SYNC_CLKout12_13  
CLKin0_MUX  
CLKin1_MUX  
SYNC0_FAST  
SYNC1_FAST  
SYNC0_AUTO  
SYNC1_AUTO  
Register  
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16.3 DEFAULT DEVICE REGISTER SETTINGS AFTER POWER ON/RESET  
The Default Device Register Settings after Power On/Reset Table below illustrates the default register settings programmed in  
silicon for the LMK018xx after power on or asserting the reset bit. Capital X and Y represent numeric values.  
Default Device Register Settings after Power On/Reset  
Default  
Value  
(decimal)  
Bit Location  
(MSB:LSB)  
Field Name  
Default State  
Field Description  
Register  
RESET  
0
Not in reset  
Performs power on reset for device  
Device power down control  
R0  
R0  
4
5
Disabled (device  
is active)  
POWERDOWN  
0
Power down the divider and clock outputs  
0 through 3  
CLKout0_3_PD  
CLKout4_7_PD  
CLKout8_11_PD  
CLKout12_13_PD  
0
0
0
0
Disabled  
Disabled  
R0  
R0  
R0  
R0  
6
7
8
9
Power down the divider and clock outputs  
4 through 7  
Disabled  
Disabled  
Power down the divider and clock outputs  
8 through 11  
Power down the divider and clock outputs  
12 through 13  
CLKin0_BUF_TYPE  
CLKin1_BUF_TYPE  
CLKin0_DIV  
0
0
2
0
2
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Bipolar  
Bipolar  
Divide by 2  
Bypass  
Divide by 2  
Bypass  
LVDS  
Clock in buffer type  
R0  
R0  
R0  
R0  
R0  
R0  
R1  
R1  
R1  
R1  
R1  
R1  
R1  
R1  
R2  
R2  
R2  
R2  
R2  
R2  
10  
Clock in buffer type  
11  
Divider value for CLKin0  
14:16 [3]  
17:18 [2]  
19:21 [3]  
22:23 [2]  
4:6 [3]  
CLKin0_MUX  
Enables or bypasses the CLKin0 divider  
Divider value for CLKin1  
CLKin1_DIV  
CLKin1_MUX  
Enables or bypasses the CLKin1 divider  
CLKout0_TYPE  
CLKout1_TYPE  
CLKout2_TYPE  
CLKout3_TYPE  
CLKout4_TYPE  
CLKout5_TYPE  
CLKout6_TYPE  
CLKout7_TYPE  
CLKout8_TYPE  
CLKout9_TYPE  
CLKout10_TYPE  
CLKout11_TYPE  
CLKout12_TYPE  
CLKout13_TYPE  
LVDS  
7:9 [3]  
Individual clock output format. Select from  
LVDS/LVPECL.  
LVDS  
10:12 [3]  
13:15 [3]  
16:19 [4]  
20:23 [4]  
24:27 [4]  
28:31 [4]  
4:7 [4]  
LVDS  
LVDS  
LVDS  
LVDS  
LVDS  
LVDS  
Individual clock output format. Select  
from LVDS/LVPECL/LVCMOS.  
LVDS  
8:11 [4]  
12:15 [4]  
16:19 [4]  
20:23 [4]  
24:27 [4]  
LVDS  
LVDS  
LVDS  
LVDS  
No delay  
Analog delay setting for CLKout12 &  
CLKout13.  
CLKout12_13_ADLY  
CLKout12_13_HS  
SYNC1_QUAL  
0
0
0
R3  
R3  
R3  
4:9 [6]  
10  
No Shift  
Half shift for digital delay.  
Not Qualified  
Allows SYNC operations to be qualified by  
a clock output  
11:12 [2]  
SYNC0_POL_INV  
1
1
0
0
Logic Low  
Logic Low  
Will sync  
Will sync  
Will sync  
R3  
R3  
R3  
R3  
14  
15  
16  
17  
Sets the polarity of the SYNC pin when  
input  
SYNC1_POL_INV  
NO_SYNC_CLKout0_3  
NO_SYNC_CLKout4_7  
Disable individual clock groups from being  
synchronized.  
NO_SYNC_CLKout8_1  
1
0
0
R3  
R3  
18  
19  
NO_SYNC_CLKout12_  
13  
Will sync  
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Default  
Value  
(decimal)  
Bit Location  
(MSB:LSB)  
Field Name  
Default State  
Field Description  
Register  
SYNC0_FAST  
SYNC1_FAST  
0
0
Disabled  
Disabled  
Automatic  
R3  
R3  
23  
24  
Enables synchronization circuitry.  
SYNC is started by programming a  
Register R5  
SYNC0_AUTO  
1
1
5
R3  
R3  
R4  
25  
26  
Automatic  
SYNC is started by programming a  
Register R4 or R5  
SYNC1_AUTO  
5 clock cycles  
Digital Delay setting for CLKout12 &  
CLKout13.  
CLKout12_13_DDLY  
4:13 [10]  
CLKout0_3_DIV  
1
1
1
0
0
1
Divide-by-1  
Divide-by-1  
Divide-by-1  
No Delay  
R5  
R5  
R5  
R5  
R5  
R5  
4:6 [3]  
7:9 [3]  
10:12 [3]  
13  
CLKout4_7_DIV  
Divider for clock outputs.  
CLKout8_11_DIV  
CLKout12_ADLY_SEL  
CLKout13_ADLY_SEL  
CLKout12_13_DIV  
Enable Digital Delay for CLKout12  
Enable Digital Delay for CLKout 13  
Divider for clock output.  
No Delay  
14  
Divide-by-1  
Writeable  
17:27 [11]  
The values of registers R0 to R5 are  
lockable  
uWireLock  
0
R15  
4
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16.4 REGISTER R0  
the signal source. The unused CLKin shouLd be AC coupled  
to ground.  
The R0 register controls reset, global power down, the power  
down functions for the channel dividers and their correspond-  
ing outputs, CLKinX divider value and CLKinX divide select.  
The X, Y in CLKoutX_Y_PD denote the actually clock output  
which may be from 0 to 13 where X is the first CLKout and Y  
is the last CLKout.  
The programming address table shows at what register the  
specified CLKinX_BUF_TYPE is located.  
The CLKinX_BUF_TYPE table shows the programming def-  
inition for these registers.  
CLKinX_BUF_TYPE Programming Addresses  
16.4.1 RESET  
CLKinX_BUF_TYPE  
CLKin0_BUF_TYPE  
CLKin1_BUF_TYPE  
Programming Address  
Setting this bit will cause the silicon default values to be set  
upon loading of R0 by a high LEuWire pin. When program-  
ming register R0 with the RESET bit set, all other pro-  
grammed values are ignored.  
R0[10]  
R0[11]  
CLKinX_BUF_TYPE  
The RESET bit is automatically cleared upon writing any other  
register. For instance, when R0 is written to again with default  
values.  
R0[10]  
CLKinX Buffer Type  
Bipolar  
0
1
If the user reprograms the R0, after the initial programming  
then set RESET = 0.  
CMOS  
16.4.3.2 CLKinX_DIV  
RESET  
These set the CLKin divide value, from 2-8.  
R0[4]  
State  
CLKinX_DIV Programming Address  
0
1
Normal operation  
CLKinX_DIV  
CLKin0_DIV  
CLKin1_DIV  
Programming Address  
R0[16:14]  
Reset (automatically cleared)  
16.4.2 POWERDOWN  
R0[21:19]  
Setting this bit causes the device to enter powerdown mode.  
Normal operation is resumed by clearing this bit with MI-  
CROWIRE. All other MICROWIRE settings are preserved  
during POWERDOWN.  
CLKinX_DIV  
R0[21:19, 16:14]  
Divide Value  
0 (0x00)  
1 (0x01)  
2 (0x02)  
3 (0x03)  
4 (0x04)  
5 (0x05)  
6 (0x06)  
7 (0x07)  
8
2
2
3
4
5
6
7
POWERDOWN  
R1[5]  
State  
0
1
Normal operation  
Powerdown  
16.4.3 CLKoutX_Y_PD  
This bit powers down the clock outputs as specified by CLK-  
outX to CLKoutY. This includes the divider and output buffers.  
CLKoutX_Y_PD Programming Addresses  
16.4.3.3 CLKinX_MUX  
CLKoutX_Y_PD  
CLKout0_3_PD  
CLKout4_7_PD  
CLKout8_11_PD  
CLKout12_13_PD  
Programming Address  
These bits select whether or not the CLKin divider is bypassed  
or enabled.  
R0[6]  
R0[7]  
R0[8]  
R0[9]  
CLKinX_MUX Programming Address  
CLKinX_MUX  
CLKin0_MUX  
CLKin1_MUX  
Programming Address  
R0[18:17]  
CLKoutX_Y_PD  
R0[23:22]  
R0[6,7,8,9]  
State  
CLKinX_MUX  
R0[23:22, 18:17]  
0
1
Power up clock group  
Power down clock group  
State  
Bypass  
Divide  
0 (0x00)  
1(0x01)  
16.4.3.1 CLKinX_BUF_TYPE  
There are two input buffer types for CLKin0 and CLKin1: bipo-  
lar or CMOS. Bipolar is recommended for differential inputs  
such as LVDS and LVPECL. CMOS is recommended for DC  
coupled single ended inputs.  
16.5 REGISTER R1 AND R2  
Registers R1 and R2 set the clock output types.  
16.5.1 CLKoutX_TYPE  
When using bipolar, CLKinX and CLKinX* input pins must be  
AC coupled when using differential or single ended input.  
The clock output types of the LMK01801 are individually pro-  
grammable. The CLKoutX_TYPE registers set the output  
type of an individual clock output to LVDS, LVPECL, LVC-  
MOS, or powers down the output buffer. Note that LVPECL  
supports three different amplitude levels and LVCMOS sup-  
When using CMOS, CLKinX and CLKinX* input pins may be  
AC or DC coupled with a differential input.  
When using CMOS in a single ended mode, the used clock  
input pin (CLKinX or CLKinX*) may be AC or DC coupled to  
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ports single LVCMOS outputs, inverted, and normal polarity  
of each output pin for maximum flexibility.  
16.6 REGISTER R3  
Register R3 sets the analog delay, digital delay half-shift and  
SYNC controls.  
The programming addresses table shows at what register and  
address the specified clock output CLKoutX_TYPE register is  
located.  
16.6.1 CLKout12_13_ADLY  
This registers controls the analog delay of the clock outputs  
12 and 13. Adding analog delay to the output will increase the  
noise floor of the output. For this analog delay to be active for  
a clock output, it must be selected with ADLY12_SEL or  
ADLY13_SEL. If neither clock output selects the analog de-  
lay, then the analog delay block is powered down.  
The CLKoutX_TYPE table shows the programming definition  
for these registers.  
CLKoutX_TYPE Programming Addresses  
CLKoutX  
CLKout0  
CLKout1  
CLKout2  
CLKout3  
CLKout4  
CLKout5  
CLKout6  
CLKout7  
CLKout8  
CLKout9  
CLKout10  
CLKout11  
CLKout12  
CLKout13  
Programming Address  
R1[4:6]  
In addition to the programmed delay, a fixed 500 ps of delay  
will be added by engaging the delay block.  
R1[7:9]  
R1[10:12]  
R1[13:15]  
R1[16:19]  
R1[20:23]  
R1[24:27]  
R1[28:31]  
R2[4:7]  
The CLKout12_13_ADLY table shows the programming def-  
inition for these registers.  
CLKout12_13_ADLY, 6bits  
R3[4:9]  
0 (0x00)  
1 (0x01)  
2 (0x02)  
3 (0x03)  
4 (0x04)  
5 (0x05)  
6 (0x06)  
7 (0x07)  
8 (0x08)  
9 (0x09)  
10 (0x0A)  
11 (0x0B)  
12 (0x0C)  
13 (0x0D)  
14 (0x0E)  
15 (0x0F)  
16 (0x10)  
17 (0x11)  
18 (0x12)  
19 (0x13)  
20 (0x14)  
21 (0x15)  
22 (0x16)  
23 (0x17)  
Definition  
500 ps + No delay  
500 ps + 25 ps  
500 ps + 50 ps  
500 ps + 75 ps  
500 ps + 100 ps  
500 ps + 125 ps  
500 ps + 150 ps  
500 ps + 175 ps  
500 ps + 200 ps  
500 ps + 225 ps  
500 ps + 250 ps  
500 ps + 275 ps  
500 ps + 300 ps  
500 ps + 325 ps  
500 ps + 350 ps  
500 ps + 375 ps  
500 ps + 400 ps  
500 ps + 425 ps  
500 ps + 450 ps  
500 ps + 475 ps  
500 ps + 500 ps  
500 ps + 525 ps  
500 ps + 550 ps  
500 ps + 575 ps  
R2[8:11]  
R2[12:15]  
R2[16:19]  
R2[20:23]  
R2[24:27]  
CLKoutX_TYPE, 4 bits  
R1[31:28,27:24,23:20,19:16],  
R2  
Definition  
[27:24,23:20,19:16,15:12,11:8,7:4]  
0 (0x00)  
1 (0x01)  
2 (0x02)  
3 (0x03)  
4 (0x04)  
Powerdown  
LVDS  
LCPECL  
Reserved  
LVPECL (1600  
mVpp)  
5 (0x05)  
6 (0x06)  
7 (0x07)  
8 (0x08)  
LVPECL (2000  
mVpp)  
LVCMOS (Norm/  
Inv)  
LVCMOS (Inv/  
Norm)  
LVCMOS (Norm/  
Norm)  
16.6.2 CLKout12_13_HS, Digital Delay Half Shift  
9 (0x09)  
LVCMOS (Inv/Inv)  
This bit subtracts a half clock cycle of the clock distribution  
path period to the digital delay of CLKout12 and CLKout13.  
CLKout12_13_HS is used together with CLKout12_13_DDLY  
to set the digital delay value.  
10 (0x0A)  
LVCMOS (Off/  
Norm)  
11 (0x0A)  
12 (0x0C)  
LVCMOS (Off/Inv)  
The state of this bit does not affect the power mode of the  
clock output group.  
LVCMOS (Norm/  
Off)  
When changing CLKout12_13_HS, the digital delay immedi-  
ately takes effect without a SYNC event.  
13 (0x0D)  
14 (0x0E)  
LVCMOS (Inv/Off)  
LVCMOS (Off/Off)  
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28  
 
 
 
CLKout12_13_HS  
NO_SYNC_CLKoutX_Y Programming Addresses  
R3[10]  
State  
NO_SYNC_CLKoutX_Y  
CLKout0 toCLKout3  
Programming Address  
0
1
Normal  
R3[16]  
R3[17]  
R3[18]  
R3[19]  
Subtract half of a clock  
distribution path period from  
the total digital delay  
CLKout4 to CLKout7  
CLKout8 to CLKout11  
CLKout12 to CLKout13  
16.6.3 SYNC1_QUAL  
NO_SYNC_CLKoutX_Y  
When SYNC1_QUAL is set clock outputs on Bank B will be  
synchronized.  
R3[19, 18, 17, 16]  
Definition  
0
1
CLKoutX_Y will synchronize  
CLKoutX_Y will not synchronize  
CLKout12 will be used as the SYNC qualification clock.  
Only CLKout12 and CLKout13 support dynamic digital delay.  
However, this permits the relative phase relationship between  
CLKout 12 and CLKout13 to be dynamically adjusted with re-  
16.6.6 SYNCX_FAST  
SYNC1_FAST must be set to 1 when using SYNC1_QUAL  
spect  
to  
all  
other  
clock  
outputs.  
When  
NO_SYNC_CLKoutX_Y = 1, the corresponding clock outputs  
will not be interrupted during the SYNC event.  
16.6.7 SYNCX_AUTO  
When set, causes a SYNC event to occur when programming  
R4 to adjust digital delay values (this will cause a SYNC event  
for Bank B only) or R5 when adjusting divide values (this will  
cause a SYNC event for both Bank A and B).  
Qualifying the SYNC means that the pulse which turns the  
clock outputs off and on will have a fixed time relationship with  
the phase of the other clock outputs.  
See Section 14.9 CLOCK OUTPUT SYNCHRONIZATION for  
more information.  
The SYNC event will coincide with the LE uWire pin falling  
edge.  
SYNC1_QUAL  
SYNCX_AUTO  
R3[11]  
0 (0x00)  
1 (0x01)  
2 (0x10)  
3 (0x11)  
Mode  
No Qualification  
Reserved  
R3[26, 25]  
Mode  
0
1
Manual SYNC  
SYNC internally generated  
Reserved  
16.7 REGISTER R4  
Qualification Enabled  
16.7.1 CLKout12_13_DDLY, Clock Channel Digital Delay  
16.6.4 SYNCX_POL_INV  
CLKout12_13_DDLY and CLKout12_13_HS sets the digital  
Sets the polarity of a SYNCX input pin. When SYNC is as-  
serted the clock outputs will transition to a low state.  
delay  
used  
for  
CLKout12  
and  
CLKout13.  
CLKout12_13_DDLY only takes effect during a SYNC event  
and if the NO_SYNC_CLKout12_13 bit is cleared for this  
clock group.  
A pull-up on the SYNCX pin results in normal operation when  
the SYNCX_POL_INV = 1 and the SYNCX input is a no con-  
nect.  
Programming CLKout12_13_DDLY can require special at-  
tention. See section Section 15.6.1 Dynamically Program-  
ming Digital Delay for more details.  
See Section 15.6 CLOCK OUTPUT SYNCHRONIZATION  
(SYNC) for more information on SYNC. A SYNC event can  
be generated by toggling this bit through the MICROWIRE  
interface.  
Using a CLKout12_13_DDLY value of 13 or greater will cause  
the clock outputs to operate in extended mode regardless of  
the clock group's divide value or the half step value.  
SYNCX_POL_INV  
One clock cycle is equal to the period of the clock distribution  
path. The period of the clock distribution path is equal to clock  
divider value divided by the CLKin1 frequency.  
R3[14, 15]  
Polarity  
0
1
SYNC is active high  
SYNC is active low  
tclock distribution path = CLKout divide value / fCLKin  
16.6.5 NO_SYNC_CLKoutX_Y  
CLKout12_13_DDLY, 10 bits  
The NO_SYNC_CLKoutX_Y bits prevent individual clock  
groups from becoming synchronized during a SYNC event. A  
reason to prevent individual clock groups from becoming syn-  
chronized is that during synchronization, the clock output is  
in a fixed low state or can have a glitch pulse.  
R4[13:4]  
Delay  
(Divide = 1)  
Delay  
(Divide >1)  
Power  
Mode  
0 (0x00)  
1 (0x01)  
2 (0x02)  
3 (0x03)  
4 (0x04)  
5 (0x05)  
6 (0x06)  
7 (0x07)  
...  
5 clock cycles 6 clock cycles  
5 clock cycles 6 clock cycles  
5 clock cycles 6 clock cycles  
5 clock cycles 6 clock cycles  
5 clock cycles 6 clock cycles  
5 clock cycles 6 clock cycles  
6 clock cycles 7 clock cycles  
7 clock cycles 8 clock cycles  
By disabling SYNC on a clock group, it will continue to operate  
normally during a SYNC event.  
Digital delay requires a SYNC operation to take effect. If  
NO_SYNC_CLKout12_13 is set before a SYNC event, the  
digital delay value will be unused.  
Normal  
Mode  
Setting the NO_SYNC_CLKoutX_Y bit has no effect on  
clocks already synchronized together.  
...  
...  
12 (0x0C)  
12 clock cycles 13 clock cycles  
29  
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R4[13:4]  
Delay  
(Divide = 1)  
Delay  
(Divide >1)  
Power  
Mode  
R5[12:10, 9:7, 6:4]  
2 (0x02)  
Divide Value  
2
3
4
5
6
7
13 (0x0D)  
...  
13 clock cycles 14 clock cycles  
3 (0x03)  
...  
...  
4 (0x04)  
520 (0x208)  
520 clock  
cycles  
521 clock  
cycles  
5 (0x05)  
Extended  
Mode  
6 (0x06)  
521 (0x209)  
522 (0x20A)  
521 clock  
cycles  
522 clock  
cycles  
7 (0x07)  
CLKout12_13_DIV, 11 bits  
522 clock  
cycles  
523 clock  
cycles  
R5[27:17]  
0 (0x00)  
1 (0x01)  
2 (0x02)  
3 (0x03)  
4 (0x04)  
5 (0x05)  
6 (0x06)  
...  
Divide Value  
Power Mode  
Invalid  
16.8 REGISTER R5  
1
Register 5 sets the clock output dividers and analog delay.  
2(Note 20)  
16.8.1 CLKout12_ADLY_SEL[13], CLKout13_ADLY_SEL  
[14], Select Analog Delay  
3
4 (Note 20)  
These bits individually select the analog delay block for use  
with CLKout12 or CLKout13. It is not required for both outputs  
of a clock output group to use analog delay, but if both outputs  
do select the analog delay block, then the analog delay will  
be the same for each output. When neither clock output uses  
analog delay, the analog delay block is powered down.  
Normal Mode  
5 (Note 20)  
6
...  
24 (0x18)  
25 (0x19)  
26 (0x1A)  
27 (0x1B)  
...  
24  
25  
CLKout12_ADLY_SEL[13], CLKout13_ADLY_SEL[14]  
26  
R5[13]  
R5[14]  
State  
27  
0
0
1
1
0
1
0
1
Analog delay powered down  
Analog delay on CLKout13  
Analog delay on CLKout12  
...  
Extended Mode  
1044 (0x414)  
1045 (0x415)  
1044  
1045  
Analog delay on both  
CLKouts  
Using a divide value of 26 or greater will cause the clock group  
to operate in extended mode regardless of the clock group's  
digital delay value.  
16.8.2 CLKoutX_Y_DIV. Clock Output Divide  
Note 20: After programming CLKout12_13_DIV a SYNC event must occur  
on the channels using this divide value (CLKout 12 and CLKout13), A SYNC  
event may be generated by changing the SYNC1_POL_INV bit or through  
the SYNC1 pin. Ensure that CLKin1 is stable before this SYNC event occurs.  
CLKoutX_Y_DIV sets the divide value for the clock outputs X  
through Y. The divide may be even or odd. Both even and odd  
divides output a 50% duty cycle clock.  
Programming CLKoutX_Y_DIV is as follows:  
16.9 REGISTER 15  
16.9.1 uWireLock  
CLKoutX_Y_DIV Programming Addresses  
CLKoutX_Y_DIV  
CLKout0_3_DIV  
CLKout4_7_DIV  
CLKout8_11_DIV  
CLKout12_13_DIV  
Programming Address  
R5[6:4]  
Setting uWireLock will prevent any changes to uWire regis-  
ters R0 to R5. Only by clearing uWireLock bit in R15 can the  
MICROWIRE registers be unlocked and written to once more.  
R5[9:7]  
R5[12:10]  
uWireLock  
R5[27:17]  
R15 [4]  
State  
CLKoutX_Y_Div, 2 bits  
0
1
Registers Unlocked  
R5[12:10, 9:7, 6:4]  
0 (0x00)  
Divide Value  
Registers locked, Write-protected  
8
1
1 (0x01)  
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30  
 
 
 
 
 
 
the device is dissipated in the external emitter resistors which  
doesn't add to the power dissipation budget for the device but  
is important for LDO ICC calculations.  
17.0 Application Information  
17.1 POWER SUPPLY  
For total current consumption of the device add up the signif-  
icant functional blocks. In this example 92 mA =  
17.1.1 Current Consumption  
(Note 22), (Note 23)  
1 mA (core current)  
22 mA (Bank A current)  
15 mA (Output Buffer current)  
21 mA (Output Divider current)  
9 mA (LVDS output current)  
From Table 10 the current consumption can be calculated for  
any configuration.  
For example, the current for the entire device with 1 LVDS  
(CLKout0) and 1 LVPECL 1600 mVpp /w 240 emitter re-  
sistors (CLKout1) output active with a clock output divide = 1,  
and no other features enabled can be calculated by adding  
the following blocks:  
24 mA (LVPECL 1600 mVpp buffer /w 240 emitter  
resistors)  
Once the total current consumption has been calculated,  
power dissipated by the device can be calculated. The power  
dissipation of the device is equel to the total current entering  
the device multiplied by the voltage at the device minus the  
power dissipated in any emitter resistors connected to any of  
the LVPECL outputs. If no emitter resistors are connected to  
the LVPECL outputs, this power will be 0 watts. Continuing  
the output with 240 emitter resistors. Total IC power = 275.1  
mW = 3.3 V * 95 mA -28.5 mW.  
Core Current  
Clock Buffer  
One LVDS Output Buffer Current  
Bank A  
Output Divider Buffer Current  
LVPECL 1600 mVpp buffer /w 240 emitter resistors  
Since there will be one LVPECL output drawing emitter cur-  
rent, this means some of the power from the current draw of  
31  
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TABLE 10. Typical Current Consumption for Selected Functional Blocks (TA = 25 °C, VCC = 3.3 V)  
Power  
Power  
dissipated  
externally  
(mW)  
Typical  
dissipated  
in device  
(mW)  
Block  
Condition  
ICC (mA)  
(Note 21)  
Core  
All outputs and dividers off  
At least on output enabled  
Core  
Bank  
1
3.3  
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Bank A  
22  
25  
72.6  
82.5  
Bank B  
At least on output enabled  
CLKout0 to CLKout3  
CLKout4 to CLKout7  
CLKout8 to CLKout11  
CLKout12 to CLKout13  
On when any on output in the group is  
enabled  
Buffers  
15  
49.5  
Divide = 1  
21  
24.2  
15  
69.3  
79.8  
49.5  
63.0  
CLKout0 to CLKout11  
Divide = 2 to 8  
Output  
Divider  
Divide = 1 to 25 and DDLY = 1 to 12  
Divide = 26 to 1045 or DDLY > 13  
Divide = 2 to 8  
CLKout12 and CLKout13  
19.1  
Bank A  
Bank B  
Input  
Divider  
9
29.7  
Divide = 2 to 8  
CLKout12_13_ADLY = 0 to 3  
CLKout12_13_ADLY = 4 to 7  
CLKout12_13_ADLY = 8 to 11  
CLKout12_13_ADLY = 12 to 15  
CLKout12_13_ADLY = 16 to 23  
3.4  
3.8  
4.2  
4.7  
5.2  
2.8  
11.2  
12.5  
13.9  
15.5  
17.2  
9.2  
Analog Delay Value  
Analog  
Delay  
When only one, CLKout12 or CLKout13, have Analog Delay Selected.  
Clock Output Buffers  
9
29.7  
46.2  
-
-
CLkout0 to CLKout11; 100 differential termination  
CLkout12 to CLKout13; 100 differential termination  
LVDS  
14  
CLkout0 to CLKout11; LVPECL 1600  
mVpp,  
24  
79.2  
97.3  
28.5  
28.5  
AC coupled using 240 emitter resistors  
CLkout12 to CLKout13; LVPECL 1600  
mVpp,  
29.5  
AC coupled using 240 emitter resistors  
10 MHz  
18.6  
23.1  
31.7  
24.7  
30.3  
42.0  
9.7  
61.4  
76.2  
104.6  
81.51  
100  
-
-
-
-
-
-
-
-
-
-
-
-
LVCMOS Pair, CLKout4 to CLKout11,  
50 MHz  
(CLKoutX_TYPE = 6 - 10), CL = 5 pF  
150 MHz  
10 MHz  
50 MHz  
150 MHz  
10 MHz  
50 MHz  
150 MHz  
10 MHz  
50 MHz  
150 MHz  
LVCMOS Pair, CLKout12 and  
CLKout13,  
(CLKoutX_TYPE = 6 - 10), CL = 5 pF  
138.6  
32  
LVCMOS Single, CLKout4 to CLKout11,  
(CLKoutX_TYPE=11 - 13), CL = 5 pF  
10.8  
13.5  
15  
35.6  
44.5  
49.5  
57.7  
75.2  
LVCMOS Single, CLKout12 and  
CLKout13,  
(CLKoutX_TYPE= 11 - 13), CL = 5 pF  
17.5  
22.8  
Note 21: Power is dissipated externally in LVPECL emitter resistors. The externally dissipated power is calculated as twice the DC voltage level of one LVPECL  
clock output pin squared over the emitter resistance. That is to say power dissipated in emitter resistors = 2 * Vem2/Rem  
Note 22: Assuming θJA = 25.8 °C/W, the total power dissipated on chip must be less than (125 °C - 85 °C) / 25.8 °C/W = 1.5 W to guarantee a junction temperature  
less than 145 °C  
Note 23: Worst case power dissipation can be estimated by multiplying typical power dissipation with a factor of 1.20  
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32  
 
 
 
 
must be soldered down to ensure adequate heat conduction  
out of the package.  
17.2 PIN CONNECTION RECOMMENDATIONS  
A recommended land and via pattern is shown in Figure 7.  
More information on soldering LLP packages and gerber foot-  
prints can be obtained: http://www.national.com/analog/pack-  
aging.  
17.2.1 Vcc Pins and Decoupling  
All Vcc pins must always be connected.  
Integrated capacitance on the IC makes high frequency de-  
coupling capacitors unnecessary. Ferrite beads should be  
used on CLKout Vcc pins to minimize crosstalk through power  
supply. When several clocks share the same frequency, a  
single ferrite bead can be shared with the common frequency  
CLKout Vcc's for power supply isolation.  
A recommended footprint including recommended solder  
mask and solder paste layers can be found at: http://  
www.national.com/analog/packaging/llp/gerber.html for the  
SQA48A package.  
To minimize junction temperature it is recommended that a  
simple heat sink be built into the PCB (if the ground plane  
layer is not exposed). This is done by including a copper area  
of about 2 square inches on the opposite side of the PCB from  
the device. This copper area may be plated or solder coated  
to prevent corrosion but should not have conformal coating (if  
possible), which could provide thermal insulation. The vias  
shown in Figure 7 should connect these top and bottom cop-  
per layers and to the ground layer. These vias act as “heat  
pipes” to carry the thermal energy away from the device side  
of the board to where it can be more effectively dissipated.  
17.2.2 Unused clock outputs  
Leave unused clock outputs floating and powered down.  
17.2.3 Unused clock inputs  
Unused clock inputs can be left floating.  
17.2.4 Bias  
Proper bypassing of the Bias pin with a 1 µF capacitor con-  
nected to Vcc4_Bias (Pin 25) is important for low noise per-  
formance.  
17.2.5 In MICROWIRE Mode  
SYNC0 and SYNC1 have an internal pullup and may be left  
as a no-connect if external SYNC is not required. MIR-  
CROWIRE SYNC may still be used in this condition.  
17.3 THERMAL MANAGEMENT  
Power consumption of the LMK01801 can be high enough to  
require attention to thermal management. For reliability and  
performance reasons the die temperature should be limited  
to a maximum of 125 °C. That is, as an estimate, TA (ambient  
temperature) plus device power consumption times θJA  
should not exceed 125 °C.  
The package of the device has an exposed pad that provides  
the primary heat removal path as well as excellent electrical  
grounding to a printed circuit board. To maximize the removal  
of heat from the package a thermal land pattern including  
multiple vias to a ground plane must be incorporated on the  
PCB within the footprint of the package. The exposed pad  
30148773  
FIGURE 7. Recommended Land and Via Pattern  
33  
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17.4 DRIVING CLKin INPUTS  
17.4.1 Driving CLKin Pins with a Differential Source  
Both CLKin ports can be driven by differential signals. It is  
recommended that the input mode be set to bipolar  
(CLKinX_BUF_TYPE = 0) when using differential reference  
clocks. The LMK01801 family internally biases the input pins  
so the differential interface should be AC coupled. The rec-  
ommended circuits for driving the CLKin pins with either  
LVDS or LVPECL are shown in Figure 8 and Figure 9.  
30148722  
FIGURE 11. DC Coupled LVCMOS/LVTTL  
Reference Clock  
If the CLKin pins are being driven with a single-ended LVC-  
MOS/ LVTTL source, either DC coupling or AC coupling may  
be used. If DC coupling is used, see Figure 12, the  
CLKinX_BUF_TYPE should be set to MOS buffer mode  
(CLKinX_BUF_TYPE = 1) and the voltage swing of the source  
must meet the specifications for DC coupled, MOS-mode  
clock inputs given in the table of Electrical Characteristics. If  
AC coupling is used, the CLKinX_BUF_TYPE should be set  
to the bipolar buffer mode (CLKinX_BUF_TYPE = 0). The  
voltage swing at the input pins must meet the specifications  
for AC coupled, bipolar mode clock inputs given in the table  
of Electrical Characteristics. In this case, some attenuation of  
the clock input level may be required. A simple resistive di-  
vider circuit before the AC coupling capacitor is sufficient.  
30148788  
FIGURE 8. CLKinX/X* Termination for an LVDS  
Reference Clock Source  
30148787  
30148785  
FIGURE 9. CLKinX/X* Termination for an LVPECL  
Reference Clock Source  
FIGURE 12. DC Coupled LVCMOS/LVTTL Reference  
Clock  
Finally, a reference clock source that produces a differential  
sine wave output can drive the CLKin pins using the circuit  
shown in Figure 10. Note: the signal level must conform to the  
requirements for the CLKin pins listed in the Section 10.0  
Electrical Characteristics.  
17.5 TERMINATION AND USE OF CLOCK OUTPUT  
(DRIVERS)  
When terminating clock drivers keep in mind these guidelines  
for optimum phase noise and jitter performance:  
Transmission line theory should be followed for good  
impedance matching to prevent reflections.  
Clock drivers should be presented with the proper loads.  
For example:  
LVDS drivers are current drivers and require a closed  
current loop.  
30148724  
LVPECL drivers are open emitters and require a DC  
path to ground.  
FIGURE 10. CLKinX/X* Single-ended Termination  
Receivers should be presented with a signal biased to  
their specified DC bias level (common mode voltage) for  
proper operation. Some receivers have self-biasing inputs  
that automatically bias to the proper voltage level. In this  
case, the signal should normally be AC coupled.  
17.4.2 Driving CLKin Pins with a Single-Ended Source  
The CLKin pins of the LMK01801 family can be driven using  
a single-ended reference clock source, for example, either a  
sine wave source or an LVCMOS/LVTTL source. Either AC  
coupling or DC coupling may be used. In the case of the sine  
wave source that is expecting a 50 load, it is recommended  
that AC coupling be used as shown in Figure 11 the circuit  
below with a 50 termination.  
It is possible to drive a non-LVPECL or non-LVDS receiver  
with an LVDS or LVPECL driver as long as the above guide-  
lines are followed. Check the datasheet of the receiver or  
input being driven to determine the best termination and cou-  
pling method to be sure that the receiver is biased at its  
optimum DC voltage (common mode voltage).  
Note: The signal level must conform to the requirements for the CLKin pins  
listed  
in  
the  
Section  
10.0  
Electrical  
Characteristics.  
CLKinX_BUF_TYPE is recommended to be set to bipolar mode  
(CLKinX_BUF_TYPE = 0).  
For example, when driving the OSCin/OSCin* input of the  
LMK04800 family, OSCin/OSCin* should be AC coupled be-  
cause OSCin/ OSCin* biases the signal to the proper DC  
level. This is only slightly different from the AC coupled cases  
described in Section 17.4.2 Driving CLKin Pins with a Single-  
Ended Source because the DC blocking capacitors are  
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34  
 
 
 
 
 
 
 
 
 
placed between the termination and the OSCin/OSCin* pins,  
but the concept remains the same. The receiver (OSCin/OS-  
Cin*) sets the input to the optimum DC bias voltage (common  
mode voltage), not the driver.  
17.5.1 Termination for DC Coupled Differential Operation  
For DC coupled operation of an LVDS driver, terminate with  
100 as close as possible to the LVDS receiver as shown in  
Figure 13.  
30148719  
FIGURE 16. Differential LVDS Operation, AC Coupling,  
External Biasing at the Receiver  
Some LVDS receivers may have internal biasing on the in-  
puts. In this case, the circuit shown in is modified by replacing  
the 50 terminations to Vbias with a single 100 resistor  
across the input pins of the receiver, as shown in Figure 17.  
When using AC coupling with LVDS outputs, there may be a  
startup delay observed in the clock output due to capacitor  
charging. The previous figures employ a 0.1 μF capacitor.  
This value may need to be adjusted to meet the startup re-  
quirements for a particular application.  
30148720  
FIGURE 13. Differential LVDS Operation, DC Coupling,  
No Biasing of the Receiver  
For DC coupled operation of an LVPECL driver, terminate  
with 50 to VCC - 2 V as shown in Figure 14. Alternatively  
terminate with a Thevenin equivalent circuit (120 resistor  
connected to VCC and an 82 resistor connected to ground  
with the driver connected to the junction of the 120 and 82  
resistors) as shown in Figure 15 for VCC = 3.3 V.  
30148782  
FIGURE 17. LVDS Termination for a Self-Biased Receiver  
LVPECL drivers require a DC path to ground. When AC cou-  
pling an LVPECL signal use 120 to 240 emitter resistors  
close to the LVPECL driver to provide a DC path to ground as  
shown in Figure 18. For proper receiver operation, the signal  
should be biased to the DC bias level (common mode voltage)  
specified by the receiver. The typical DC bias voltage for  
LVPECL receivers is 2 V.  
30148718  
FIGURE 14. Differential LVPECL Operation, DC Coupling  
A typical application is shown in Figure 18, where Rem=120  
to 240 . Refer to the reciever input recommendations to  
determine if the proper value of CA's, if needed.  
30148721  
30148717  
FIGURE 15. Differential LVPECL Operation, DC Coupling,  
Thevenin Equivalent  
FIGURE 18. Differential LVPECL Operation, AC Coupling,  
External Biasing at the Receiver,  
Rem=120 Ω to 240 Ω  
17.5.2 Termination for AC Coupled Differential Operation  
AC coupling allows for shifting the DC bias level (common  
mode voltage) when driving different receiver standards.  
Since AC coupling prevents the driver from providing a DC  
bias voltage at the receiver it is important to ensure the re-  
ceiver is biased to its ideal DC level.  
17.5.3 Termination for Single-Ended Operation  
A balun can be used with either LVDS or LVPECL drivers to  
convert the balanced, differential signal into an unbalanced,  
single-ended signal.  
When driving non-biased LVDS receivers with an LVDS driv-  
er, the signal may be AC coupled by adding DC blocking  
capacitors, however the proper DC bias point needs to be  
established at the receiver. One way to do this is with the ter-  
mination circuitry in Figure 16.  
It is possible to use an LVPECL driver as one or two separate  
800 mVpp signals. When using only one LVPECL driver of a  
CLKoutX/CLKoutX* pair, be sure to properly terminated the  
unused driver. When DC coupling one of the LMK04800 fam-  
ily clock LVPECL drivers, the termination should be 50 to  
35  
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VCC - 2 V as shown in Figure 19. The Thevenin equivalent  
circuit is also a valid termination as shown in Figure 20 for Vcc  
= 3.3 V.  
50 termination with the proper DC bias level for the receiver.  
The typical DC bias voltage for LVPECL receivers is 2 V (See  
Section 17.5.2 Termination for AC Coupled Differential Op-  
eration). If the companion driver is not used it should be  
terminated with either a proper AC or DC termination. This  
latter example of AC coupling a single-ended LVPECL signal  
can be used to measure single-ended LVPECL performance  
using a spectrum analyzer or phase noise analyzer. When  
using most RF test equipment no DC bias point (0 VDC) is  
required for safe and proper operation. The internal 50 ter-  
mination of the test equipment correctly terminates the  
LVPECL driver being measured as shown in Figure 21.  
30148715  
FIGURE 19. Single-Ended LVPECL Operation,  
DC Coupling  
30148714  
FIGURE 21. Single-Ended LVPECL Operation, AC  
Coupling  
30148716  
Rem=120 Ω to 240 Ω  
FIGURE 20. Single-Ended LVPECL Operation, DC  
Coupling, Thevenin Equivalent  
When AC coupling an LVPECL driver use a 120 to 240 Ω  
emitter resistor to provide a DC path to ground and ensure a  
www.ti.com  
36  
 
 
 
18.0 Physical Dimensions inches (millimeters) unless otherwise noted  
19.0 Ordering Information  
Order Number  
LMK01801BISQ  
LMK01801BISQE  
LMK01801BISQX  
Package Marking  
K01801BI  
Packaging  
1000 units  
250 units  
2500 units  
37  
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Notes  
www.ti.com  
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