LMH2180
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SNAS419D – JANUARY 2008 – REVISED MARCH 2013
LMH2180 75 MHz Dual Clock Buffer
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FEATURES
DESCRIPTION
•
The LMH2180 is a high speed dual clock buffer
designed
for
portable
communications
and
applications requiring multiple accurate multi-clock
systems. The LMH2180 integrates two 75 MHz low
noise buffers with independent shutdown pins into a
small package. The LMH2180 ensures superb
system operation between the baseband and the
oscillator signal path by eliminating crosstalk between
the multiple clock signals.
1
2
•
•
•
•
•
•
•
•
•
•
•
•
(Typical Values are: VSUPPLY = 2.7V and CL = 10
pF, unless Otherwise Specified.)
Small Signal Bandwidth 78 MHz
Supply Voltage Range 2.4V to 5V
Phase Noise (VIN = 1 VPP, fC = 38.4 MHz, Δf = 1
kHz) −123 dBc/Hz
Slew Rate 106 V/μs
Total Supply Current 2.3 mA
Shutdown Current 30 µA
Rail-to-Rail Input and Output
Individual Buffer Enable Pins
Rapid Ton Technology
Crosstalk Rejection Circuitry
Packages:
– 8-Pin WSON, Solder Bump and no Pullback
– 8-Bump DSBGA
Temperature Range −40°C to 85°C
Unique technology and design provides the LMH2180
with the ability to accurately drive both large
capacitive and resistive loads. Low supply current
combined with shutdown pins for each channel
means the LMH2180 is ideal for battery powered
applications. This part does not use an internal
ground reference, thus providing additional system
flexibility.
The flexible buffers provide system designers the
capacity to manage complex clock signals in the
latest wireless applications. Each buffer delivers 106
V/μs internal slew rate with independent shutdown
and duty cycle precision. Each input is internally
biased to 1V, removing the need for external
resistors. Both channels have rail-to-rail inputs and
outputs, a gain of one, and are AC coupled with the
use of one capacitor.
APPLICATIONS
•
•
•
•
•
3G Mobile Applications
WLAN–WiMAX Modules
TD_SCDMA Multi-Mode MP3 and Camera
GSM Modules
Oscillator Modules
Replacing a discrete buffer solution with the
LMH2180 provides many benefits: simplified board
layout, minimized parasitic components, simplified
BOM, design durability across multiple applications,
simplification of clock paths, and the ability to reduce
the number of clock signal generators in the system.
The LMH2180 is produced in the tiny packages
minimizing the required PCB space.
TYPICAL APPLICATION
VCC
Enable 1
EN1
8
IN1
2
VCTCXO
1
7
1
OUT1
LOAD1
Rload
10 nF
Cload
LMH2180
IN2
3
EN2
4
6
2
OUT2
LOAD2
Rload
Cload
5
Enable 2
GND
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2008–2013, Texas Instruments Incorporated
LMH2180
SNAS419D – JANUARY 2008 – REVISED MARCH 2013
www.ti.com
CONNECTION DIAGRAMS
Top View
Top View
EN1
VDD
1
IN 1
2
8
ENABLE 1
7
OUT 1
VDD
A3
IN1
A2
IN2
A1
DEVICE
CODE
IN 2
3
6
OUT 2
ENABLE 2
4
5
VSS
B3
B1
C3
OUT1
C2
OUT2
C1
VSS
EN2
Figure 1. 8-Pin WSON Package
See Package Number NGW0008A or NGQ0008A
Figure 2. 8-Bump DSBGA Package
See Package Number YFQ0008AAA
PIN DESCRIPTIONS
Pin No.
WSON
Pin No.
DSBGA
1
A3
VDD
Voltage supply connection
2
A2
IN 1
Input 1
3
A1
IN 2
Input 2
4
B1
ENABLE 2
5
C1
VSS
6
C2
OUT 2
Output 2
7
C3
OUT 1
Output 1
8
B3
ENABLE 1
Pin Name
Description
Enable buffer 2
Ground connection
Enable buffer 1
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ABSOLUTE MAXIMUM RATINGS
+
(1) (2)
−
Supply Voltages (V – V )
5.5V
ESD Tolerance
Human Body
(3)
Machine Model
2000V
(4)
200V
Charged Device Model
1000V
−65°C to 150°C
Storage Temperature Range
Junction Temperature
(5)
150°C
Soldering Information
Infrared or Convection (35 sec.)
(1)
(2)
(3)
(4)
(5)
2
235°C
“Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of
the device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or
other conditions beyond those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating
Conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. All
voltages are measured with respect to the ground pin, unless otherwise specified.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
Human body model, applicable std. JESD22–A114C.
Machine model, applicable std. JESD22–A115–A.
The maximum power dissipation must be derated at elevated temperatures and is dictated by TJ(MAX), θJA , and the ambient temperature
TA. The maximum allowable power dissipation is PDMAX = (TJMAX − TA) / θJA or the number given in the Absolute Maximum Ratings,
whichever is lower.
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OPERATING RATINGS
(1)
Supply Voltage (V+ – V−)
2.4V to 5.0V
(2) (3)
−40°C to 85°C
Temperature Range
Package Thermal Resistance
(2) (3)
8-Pin WSON (θJA)
217°C/W
8-Bump DSBGA (θJA)
(1)
(2)
(3)
90°C/W
“Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur, including inoperability and degradation of
the device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or
other conditions beyond those indicated in the Recommended Operating Conditions is not implied. The Recommended Operating
Conditions indicate conditions at which the device is functional and the device should not be operated beyond such conditions. All
voltages are measured with respect to the ground pin, unless otherwise specified.
The Electrical Characteristics tables show performance under the specified Recommended Operating Conditions except as otherwise
modified by the Electrical Characteristics Conditions and/or Notes. Typical values represent typical performance as measured by
production tests. Individual parts may vary.
The maximum power dissipation must be derated at elevated temperatures and is dictated by TJ(MAX), θJA , and the ambient temperature
TA. The maximum allowable power dissipation is PDMAX = (TJMAX − TA) / θJA or the number given in the Absolute Maximum Ratings,
whichever is lower.
2.7V ELECTRICAL CHARACTERISTICS
Unless otherwise specified, all limits are specified for TA = 25°C, VDD = 2.7V, VSS = 0V, VCM = 1V, Enable1,2 = VDD, CL = 10
pF, RL = 30 kΩ, Load is connected to VSS, CCOUPLING = 10 nF. Boldface limits apply at temperature range extremes of
operating condition. (1)
Parameter
Test Conditions
Min
(2)
Typ
(3)
Max
(2)
Units
Frequency Domain Response
SSBW
Small Signal Bandwidth
VIN = 100 mVPP; −3 dB
LSBW
Large Signal Bandwidth
GFN
Gain Flatness < 0.1 dB
78
MHz
VIN = 1.0 VPP; −3 dB
60
MHz
f > 100 kHz
4.9
MHz
VIN = 1 VPP, fC = 38.4 MHz, Δf = 1 kHz
−123
dBc/Hz
VIN = 1 VPP, fC = 38.4 MHz, Δf = 10
kHz
−132
dBc/Hz
Distortion and Noise Performance
φn
Phase Noise
en
Input-Referred Voltage Noise
f = 1 MHz, RSOURCE = 50Ω
13
nV/√Hz
ISOLATION
Output to Input
f = 1 MHz, RSOURCE = 50Ω
84
dB
CT
Crosstalk Rejection
f = 38.4 MHz, VIN = 1 VPP
41
dB
0.1 VPP Step (10-90%)
6
ns
Time Domain Response
tr
Rise Time
tf
Fall Time
5
ns
ts
Settling Time to 0.1%
1 VPP Step
120
ns
OS
Overshoot
0.1 VPP Step
37
%
VIN = 2 VPP
106
V/µs
Enable1,2 = VDD ; No Load
2.3
2.7
2.9
mA
Enable1 = VDD , Enable2 = VSS , No
Load
1.3
1.5
1.6
mA
Enable1,2 = VSS ; No Load
30
41
46
μA
SR
Slew Rate
(4)
Static DC Performance
IS
Supply Current
PSRR
(1)
(2)
(3)
(4)
Power Supply Rejection Ratio
DC (3.0V to 5.0V)
65
64
68
dB
The Electrical Characteristics tables show performance under the specified Recommended Operating Conditions except as otherwise
modified by the Electrical Characteristics Conditions and/or Notes. Typical values represent typical performance as measured by
production tests. Individual parts may vary.
Datasheet min/max limits are specified by test or statistical analysis.
Typical values represent the most likely parametric norms at TA = +25°C, and at the Recommended Operation Conditions at the time of
product characterization.
Slew rate is the average of the rising and falling slew rates.
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SNAS419D – JANUARY 2008 – REVISED MARCH 2013
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2.7V ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise specified, all limits are specified for TA = 25°C, VDD = 2.7V, VSS = 0V, VCM = 1V, Enable1,2 = VDD, CL = 10
pF, RL = 30 kΩ, Load is connected to VSS, CCOUPLING = 10 nF. Boldface limits apply at temperature range extremes of
operating condition.(1)
Parameter
Test Conditions
ACL
Small Signal Voltage Gain
VOS
Output Offset Voltage
TC VOS
Temperature Coefficient Output Offset
Voltage (5)
ROUT
Output Resistance
Min
VIN = 0.2 VPP
(2)
0.95
Typ
(3)
Max
(2)
1.05
V/V
-0.5
17
18
mV
2.8
f = 100 kHz
Units
1.0
µV/°C
0.6
f = 38.4 MHz
Ω
166
disabled
High Impedance
Miscellaneous Performance
RIN
Input Resistance per Buffer
CIN
Input Capacitance per Buffer
ZIN
Input Impedance
VO
ISC
Enable = VDD
137
Enable = VSS
137
Enable = VDD
1.3
Enable = VSS
1.3
f = 38.4 MHz, Enable = VDD
4.5
f = 38.4 MHz, Enable = VSS
4.2
Output Swing Positive
VIN = VDD
Output Swing Negative
VIN = VSS
Output Short-Circuit Current
(6) (7)
2.66
2.65
Sourcing, VIN = VDD, VOUT = VSS
−21
−18
−25
Sinking, VIN = VSS, VOUT = VDD
23
15
25
V
mV
mA
Enable High Active Minimum Voltage
1.2
Enable Low Inactive Maximum Voltage
0.6
(7)
kΩ
35
37
19
Ven_lmax
(6)
pF
2.69
Ven_hmin
(5)
kΩ
V
Average Temperature Coefficient is determined by dividing the changing in a parameter at temperature extremes by the total
temperature change.
Short−Circuit test is a momentary test. Continuous short circuit operation at elevated ambient temperature can result in exceeding the
maximum allowed junction temperature of 150°C.
Positive current corresponds to current flowing into the device.
5V ELECTRICAL CHARACTERISTICS
Unless otherwise specified, all limits are specified for TA = 25°C, VDD = 5V, VSS = 0V, VCM = 1V, Enable1,2 = VDD, CL = 10 pF,
RL = 30 kΩ, Load is connected to VSS, CCOUPLING = 10 nF. Boldface limits apply at temperature range extremes of operating
condition. (1)
Parameter
Test Conditions
Min
(2)
Typ
(3)
Max
(2)
Units
Frequency Domain Response
SSBW
Small Signal Bandwidth
VIN = 100 mVPP; −3 dB
87
MHz
LSBW
Large Signal Bandwidth
VIN = 1.0 VPP; −3 dB
68
MHz
GFN
Gain Flatness < 0.1 dB
f > 100 kHz
25
MHz
VIN = 1 VPP, fC = 38.4 MHz, Δf = 1 kHz
−123
dBc/Hz
VIN = 1 VPP, fC = 38.4 MHz, Δf = 10
kHz
−132
dBc/Hz
Distortion and Noise Performance
φn
(1)
(2)
(3)
4
Phase Noise
The Electrical Characteristics tables show performance under the specified Recommended Operating Conditions except as otherwise
modified by the Electrical Characteristics Conditions and/or Notes. Typical values represent typical performance as measured by
production tests. Individual parts may vary.
Datasheet min/max limits are specified by test or statistical analysis.
Typical values represent the most likely parametric norms at TA = +25°C, and at the Recommended Operation Conditions at the time of
product characterization.
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5V ELECTRICAL CHARACTERISTICS (continued)
Unless otherwise specified, all limits are specified for TA = 25°C, VDD = 5V, VSS = 0V, VCM = 1V, Enable1,2 = VDD, CL = 10 pF,
RL = 30 kΩ, Load is connected to VSS, CCOUPLING = 10 nF. Boldface limits apply at temperature range extremes of operating
condition.(1)
Parameter
Test Conditions
Min
(2)
Typ
(3)
Max
(2)
Units
en
Input-Referred Voltage Noise
f = 1 MHz, RSOURCE = 50Ω
12
nV/√Hz
ISOLATION
Output to Input
f = 1 MHz, RSOURCE = 50Ω
84
dB
CT
Crosstalk Rejection
f = 38.4 MHz, PIN = 0 dBm
59
dB
0.1 VPP Step (10-90%)
6
ns
Time Domain Response
tr
Rise Time
tf
Fall Time
6
ns
ts
Settling Time to 0.1%
1 VPP Step
70
ns
OS
Overshoot
0.1VPP Step
13
%
SR
Slew Rate
VIN = 2 VPP
124
V/µs
Enable1,2 = VDD ; No Load
3.4
4.0
4.1
mA
Enable1 = VDD, Enable2 = VSS ; No
Load
1.8
2.2
2.3
mA
Enable1,2 = VSS ; No Load
32
43
49
μA
(4)
Static DC Performance
IS
Supply Current
PSRR
Power Supply Rejection Ratio
DC (3.0V to 5.0V)
ACL
Small Signal Voltage Gain
VIN = 0.2 VPP
VOS
Output Offset Voltage
TC VOS
Temperature Coefficient Output Offset
Voltage (5)
ROUT
Output Resistance
65
64
68
0.95
1.0
1.05
V/V
−1.4
21
22
mV
dB
2.4
f = 100 kHz
0.5
f = 38.4 MHz
126
disabled
µV/°C
Ω
High Impedance
Miscellaneous Performance
RIN
Input Resistance per Buffer
CIN
Input Capacitance per Buffer
ZIN
Input Impedance
VO
ISC
Enable = VDD
138
Enable = VSS
138
Enable = VDD
1.3
Enable = VSS
1.3
f = 38.4 MHz, Enable = VDD
4.3
f = 38.4 MHz, Enable = VSS
4.2
Output Swing Positive
VIN = VDD
Output Swing Negative
VIN = VSS
Output Short-Circuit Current
(6) (7)
4.96
4.95
10
Sourcing, VIN = VDD, VOUT = VSS
−80
−62
−90
Sinking, VIN = VSS, VOUT = VDD
60
43
65
Enable High Active Minimum Voltage
1.2
Enable Low Inactive Maximum Voltage
0.6
(7)
kΩ
V
35
50
mV
mA
Ven_lmax
(6)
pF
4.99
Ven_hmin
(4)
(5)
kΩ
V
Slew rate is the average of the rising and falling slew rates.
Average Temperature Coefficient is determined by dividing the changing in a parameter at temperature extremes by the total
temperature change.
Short−Circuit test is a momentary test. Continuous short circuit operation at elevated ambient temperature can result in exceeding the
maximum allowed junction temperature of 150°C.
Positive current corresponds to current flowing into the device.
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BLOCK DIAGRAM
ENABLE 1
VDD
IN 1
1
OUT 1
IN 2
2
OUT 2
ENABLE 2
6
VSS
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TYPICAL PERFORMANCE CHARACTERISTICS
TA = 25°C, VDD = 2.7V, VSS = 0V, Enable1,2 = VDD, CL = 10 pF, RL = 30 kΩ and CCOUPLING = 10 nF, unless otherwise specified.
Frequency Response
Phase Response
6
0
2.7V
3
-30
2.7V
0
5V
PHASE (°)
GAIN (dB)
-60
-3
5V
-6
-90
-120
-9
-150
-12
VIN = 0.1VPP
VIN = 0.1VPP
-15
100k
1M
10M
-180
100k
100M
FREQUENCY (Hz)
1M
10M
100M
FREQUENCY (Hz)
Figure 3.
Figure 4.
Frequency Response Over Temperature
Frequency Response Over Temperature
6
6
-40°C
-40°C
3
3
25°C
0
0
GAIN (dB)
GAIN (dB)
85°C
-3
-6
85°C
-6
-9
-12
25°C
-3
-9
-12 V = 0.1V
IN
PP
VS = 5V
-15
100k
1M
VIN = 0.1VPP
VS = 2.7V
-15
100k
1M
10M
100M
FREQUENCY (Hz)
10M
FREQUENCY (Hz)
Figure 5.
Figure 6.
Phase Response Over Temperature
Phase Response Over Temperature
0
0
-40°C
-40°C
-30
-30
-60
-60
25°C
-90
25°C
PHASE (°)
PHASE (°)
100M
85°C
-120
-150
-90
85°C
-120
-150
-180
-180
-210 VIN = 0.1VPP
VS = 2.7V
-240
100k
1M
-210 VIN = 0.1VPP
VS = 5V
-240
100k
1M
10M
100M
FREQUENCY (Hz)
10M
100M
FREQUENCY (Hz)
Figure 7.
Figure 8.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA = 25°C, VDD = 2.7V, VSS = 0V, Enable1,2 = VDD, CL = 10 pF, RL = 30 kΩ and CCOUPLING = 10 nF, unless otherwise specified.
Large Signal Bandwidth
Gain Flatness < 0.1 dB (GFN)
6
0.5
2.7V
0.4
NORMALIZED GAIN (dB)
3
GAIN (dB)
0
-3
5V
-6
-9
-12
1M
10M
2.7V
0.2
0.1
0
-0.1
5V
-0.2
-0.3
-0.4
VIN = 1VPP
-15
100k
0.3
VIN = 0.1VPP
-0.5
100k
100M
1M
FREQUENCY (Hz)
Figure 9.
Phase Noise
-70
180
-80
160
PHASE NOISE (dBc/Hz)
VOLTAGE NOISE (nV/íHz)
Voltage Noise
2.7V
120
100
80
60
5V
-90
-100
-120
-130
1k
10k
100k
Mean ±3σ
-150
10
1M
1k
10k
100k
Figure 11.
Figure 12.
Isolation Output to Input
vs.
Frequency
Crosstalk Rejection
vs.
Frequency
100
1M
100
90
90
CROSSTALK REJECTION (dB)
2.7V
80
70
60
50
5V
40
30
20
10
0
100k
100
OFFSET FREQUENCY (Hz)
FREQUENCY (Hz)
ISOLATION (dB)
Limited number
of samples
-110
-140
20
80
5V
70
60
50
2.7V
40
30
20
10
1M
10M
100M
FREQUENCY (Hz)
PIN = 0 dBm
0
100k
1M
10M
100M
FREQUENCY (Hz)
Figure 13.
8
VS = 2.7 or 5V
VIN = 1VPP
fC = 38.4 MHz
40
0
100
100M
Figure 10.
200
140
10M
FREQUENCY (Hz)
Figure 14.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA = 25°C, VDD = 2.7V, VSS = 0V, Enable1,2 = VDD, CL = 10 pF, RL = 30 kΩ and CCOUPLING = 10 nF, unless otherwise specified.
Transient Response Positive
1100
Transient Response Negative
1100
2.7V
1075
1075
1050
1050
1025
5V
VOUT (mV)
VOUT (mV)
VIN = 0.1VPP
1000
975
950
1025
1000
5V
975
950
2.7V
925
900
0
20
40
60
80
VIN = 0.1VPP
925
100 120 140 160
900
0
20
40
TIME (ns)
Small Signal Pulse Response
Small Signal Pulse Response
1100
VS = 2.7V
VIN = 0.1VPP
f = 1 MHz
VS = 5V
VIN = 0.1VPP
f = 1 MHz
1050
VOUT (mV)
VOUT (mV)
1050
1000
950
1000
950
200
400
600
800
900
0
1000
200
TIME (ns)
400
600
800
1000
TIME (ns)
Figure 17.
Figure 18.
Large Signal Response
Large Signal Response
2.0
2.0
VS = 2.7V
VIN = 1VPP
f = 1 MHz
VS = 5V
VIN = 1VPP
f = 1 MHz
1.5
VOUT (V)
1.5
VOUT (V)
100 120 140 160
Figure 16.
1100
1.0
0.5
0.0
0
80
TIME (ns)
Figure 15.
900
0
60
1.0
0.5
200
400
600
800
0.0
0
1000
TIME (ns)
200
400
600
800
1000
TIME (ns)
Figure 19.
Figure 20.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA = 25°C, VDD = 2.7V, VSS = 0V, Enable1,2 = VDD, CL = 10 pF, RL = 30 kΩ and CCOUPLING = 10 nF, unless otherwise specified.
ISUPPLY
vs.
VSUPPLY
ISUPPLY
vs.
VSUPPLY
4.0
2.4
3.5
2.1
1.8
-40°C
2.5
ISUPPLY (mA)
ISUPPLY (mA)
3.0
25°C
2.0
85°C
1.5
1.5
85°C
0.9
1.0
0.6
0.5
2.5
3.0
3.5
4.0
4.5
0.0
2.0
5.5
2.5
3.0
4.5
Figure 21.
Figure 22.
ISUPPLY
vs.
VSUPPLY
PSRR
vs.
Frequency
80
5.0
5.5
5V
70
60
85°C
50
PSRR (dB)
-40°C
25°C
2.7V
40
30
20
No Load
Enable1,2 = VSS
05
2.0
2.5
3.0
3.5
4.0
4.5
5.0
10
0
10
5.5
100
VSUPPLY (V)
1k
10k
100k
1M
FREQUENCY (Hz)
Figure 23.
Figure 24.
VOS
vs.
ROUT
vs.
Frequency
VSUPPLY
2.0
300
1.5
250
5V
85°C 25°C
0.5
2.7V
200
ROUT (Ö)
VOS (mV)
4.0
VSUPPLY (V)
35
40
30
35
30
25
25
20
20
15
15
10
5
10
0
1.0
3.5
VSUPPLY (V)
40
0
5.0
No Load
Enable1 = VDD
Enable2 = VSS
0.3
No Load
Enable1,2 = VDD
0.0
2.0
ISUPPLY (éA)
-40°C
25°C
1.2
-40°C
0.0
-0.5
150
100
-1.0
50
-1.5
-2.0
2.5
3.0
3.5
4.0
4.5
0
10k
5.0
VSUPPLY (V)
1M
10M
100M
FREQUENCY (Hz)
Figure 25.
10
100k
Figure 26.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA = 25°C, VDD = 2.7V, VSS = 0V, Enable1,2 = VDD, CL = 10 pF, RL = 30 kΩ and CCOUPLING = 10 nF, unless otherwise specified.
Input Impedance
vs.
Frequency
150
VOUT
vs.
IOUT (Sourcing)
1.5
2.7V
-40°C
25°C
120
90
VOUT (V)
IMPEDANCE (kÖ)
1.0
5V
60
85°C
0.5
0.0
30
Open Input
VS = 2.7V
0
10k
100k
1M
10M
-0.5
-25
100M
-20
-15
Figure 27.
Figure 28.
VOUT
vs.
IOUT (Sourcing)
VOUT
vs.
IOUT (Sinking)
3.0
1.5
3.0
2.5
VOUT (V)
VOUT (V)
1.0
0.5
25°C
0.0
85°C
85°C
VS = 2.7V
2.5
2.0
2.0
25°C
1.5
1.5
1.0
1.0
0.5
-0.5
0.0
0.5
Open Input
VS = 5V
-1.0
-90 -80 -70 -60 -50 -40 -30 -20 -10 0
0.0
-40°C
0
5
10
15
20
25
IOUT (mA)
IOUT (mA)
Figure 29.
Figure 30.
VOUT
vs.
IOUT (Sinking)
ISC Sourcing
vs.
VSUPPLY Over Temperature
3.0
0
Open Input
VS = 5V
85°C
-20
2.0
-40
85°C
25°C
1.5
25°C
ISC (mA)
VOUT (V)
0
Open Input
-40°C
-60
1.0
-80
-40°C
0.5
0.0
0
-5
IOUT (mA)
FREQUENCY (Hz)
2.5
-10
10
20
30
40
50
-100
60
-120
2.5
-40°C
VIN = VDD
VOUT = VSS
3.0
3.5
4.0
4.5
5.0
VSUPPLY (V)
IOUT (mA)
Figure 31.
Figure 32.
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TYPICAL PERFORMANCE CHARACTERISTICS (continued)
TA = 25°C, VDD = 2.7V, VSS = 0V, Enable1,2 = VDD, CL = 10 pF, RL = 30 kΩ and CCOUPLING = 10 nF, unless otherwise specified.
ISC Sinking
vs.
VSUPPLY Over Temperature
100
ISUPPLY
vs.
VENABLE
2.5
VIN = VSS
100
2.5
VOUT = VDD
2.0
2.0
-40°C
60
60
40
40
ISUPPLY (mA)
ISC (mA)
80
80
85°C
25°C
20
85°C
1.5
1.5
25°C
1.0
1.0
-40°C
0.5
20
0
0.5
0.0
No Load
VS = 2.7V
0.0
0
2.5
3.0
3.5
4.0
4.5
0.0
5.0
VSUPPLY (V)
0.4
0.8
1.2
1.6
2.0
VENABLE (V)
Figure 33.
Figure 34.
ISUPPLY
vs.
VENABLE
4.0
-40°C
25°C
3.5
85°C
ISUPPLY (mA)
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0.0
No Load
VS = 5V
0.4
0.8
1.2
1.6
2.0
VENABLE (V)
Figure 35.
12
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SNAS419D – JANUARY 2008 – REVISED MARCH 2013
APPLICATION INFORMATION
GENERAL
The LMH2180 is designed to minimize the effects of spurious signals from the base chip to the oscillator. Also
the influence of varying load resistance and capacitance to the oscillator is minimized, while the drive capability is
increased.
The inputs of the LMH2180 are internally biased at 1V, making AC coupling possible without external bias
resistors.
To optimize current consumption, a buffer that is not in use can be disabled by connecting it's enable pin to VSS.
The LMH2180 has no internal ground reference; therefore, either single or split supply configurations can be
used.
The LMH2180 is an easy replacement for discrete circuitry. It simplifies board layout and minimizes the effect of
layout related parasitic components.
INPUT CONFIGURATION
The internal 1V input biasing allows AC coupling of the input signal. This biasing avoids the use of external
resistors, as depicted in Figure 36. The biasing prevents a large DC load at the oscillators output that creates a
load impedance and may affect it's oscillating frequency. As a result of this biasing, the maximum amplitude of
the AC signal is 2VPP.
The coupling capacitance C1 should be large enough to let the AC signal pass. This is a unity gain buffer with
rail-to-rail inputs and outputs.
VDD
ENABLE
1V
OSC
IN
OUT
C1
VSS
Figure 36. Input Configuration
FREQUENCY PULLING
Frequency pulling is the frequency variation of an oscillator caused by a varying load. In the typical application,
the load of the oscillator is a fixed capacitor (C1) in series with the input impedance of the buffer.
To keep the input impedance as constant as possible, the input is biased at 1V, even when the part is disabled.
A simplified schematic of the input configuration is shown in Figure 36.
ISOLATION AND CROSSTALK
Output to input isolation prevents the clock signal of the oscillator from being affected by spurious signals
generated by the digital blocks behind the output buffer. See Figure 13.
A block diagram of the isolation is shown in Figure 37. Crosstalk rejection between buffers prevents signals from
affecting each other. Figure 37 shows a Baseband IC and a Bluetooth module as an example. See Figure 14 for
more information.
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LMH2180
Base
band IC
OUT 1
IN 1
C1
Isolation
Crosstalk
VCTCXO
Bluetooth
IN 2
OUT 2
WLAN
Figure 37. Isolation Block Diagram
DRIVING CAPACITIVE LOADS
Each buffer can drive a capacitive load. Be aware that every capacitor directly connected to the output becomes
part of the loop of the buffer. In most applications the load consists of the capacitance of copper tracks and the
input capacitance of the application blocks. Capacitance reduces the gain/phase margin and decreases the
stability. This leads to peaking in the frequency response and in extreme situations oscillations can occur. To
drive a large capacitive load it is recommended to include a series resistor between the buffer and the load
capacitor. The best value for this isolation resistance can be found by experimentation.
The LMH2180 datasheet reflects measurements with capacitive loads of 10 pF at the output of the buffers. Most
common applications will probably use a lower capacitive load, which will result in lower peaking and significantly
greater bandwidth, see Figure 38.
9
33 pF
22 pF
10 pF
6
3
GAIN (dB)
0
-3
6.8 pF
No C Load
-6
-9
-12
-15
VIN = 0.1VPP
-18
1M
10M
100M
FREQUENCY (Hz)
Figure 38. Bandwidth and Peaking
PHASE NOISE
A clock buffer adds noise to the clock signal. This noise causes uncertainty in the phase of the clock signal. This
uncertainty is described by jitter (time domain) or phase noise (frequency domain). Communication systems,
such as Wireless LAN, require a low jitter/phase noise clock signal to obtain a low Bit Error Rate. Figure 39
shows the frequency domain representation of a clock signal with frequency fC. Without Phase Noise the entire
signal power would only be located at the frequency fC. Phase Noise spreads some of the power to adjacent
frequencies. Phase Noise is usually specified in dBc/Hz at a given frequency offset Δf from the carrier, where
dBc is the power level in dB relative to the carrier. The noise power is measured within a 1 Hz bandwidth.
14
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POWER (dB)
www.ti.com
Phase Noise
(dBc/Hz)
Âf
BW = 1 Hz
fC
FREQUENCY (Hz)
Figure 39. Phase Noise
Figure 40 shows the setup used to measure the LMH2180 phase noise. The clock driving the LMH2180 is a
state of the art 38.4MHz TCXO. Both the TCXO phase noise and the phase noise at the LMH2180 output were
measured. At offset frequencies of 1 kHz and higher from the carrier, the TCXO phase noise is sufficiently low to
accurately calculate the LMH2180 contribution to the phase noise at the output. The LMH6559, whose phase
noise contribution can be neglected, is used to drive the 50Ω input impedance of the Signal Source Analyzer.
LAYOUT DESIGN RECOMMENDATION
Careful consideration during circuit design and PCB layout will eliminate problems and will optimize the
performance of the LMH2180. It is best to have the same ground plane on the PCB for all decoupling and other
ground connections.
To ensure a clean supply voltage it is best to place decoupling capacitors close to the LMH2180, between VDD
and VSS.
Another important issue is the value of the components, because this also determines the sensitivity to
disturbances. Resistor values have to be low enough to avoid a significant noise contribution and large enough to
avoid a significant increase in power consumption while loading inputs or outputs to heavily.
VDD
Enable 1
EN1
8
E5052A/B
LMH6559
1
10 nF
IN1
2
TCXO
7
1
OUT1
50:
10 nF
LMH2180
38.4 MHz
Signal Source
Analyzer
IN2
3
EN2
4
Buffer for
driving 50:
6
2
5
Enable 2
VSS
Figure 40. Measurement Setup
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REVISION HISTORY
Changes from Revision C (March 2013) to Revision D
•
16
Page
Changed layout of National Data Sheet to TI format .......................................................................................................... 15
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PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
LMH2180SD/NOPB
ACTIVE
WSON
NGQ
8
1000
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
2180S
LMH2180SDE/NOPB
ACTIVE
WSON
NGQ
8
250
RoHS & Green
SN
Level-1-260C-UNLIM
-40 to 85
2180S
LMH2180TM/NOPB
ACTIVE
DSBGA
YFQ
8
250
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
A
LMH2180TMX/NOPB
ACTIVE
DSBGA
YFQ
8
3000
RoHS & Green
SNAGCU
Level-1-260C-UNLIM
A
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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