National Semiconductor LMH2180 Technical data

LMH2180
75 MHz Dual Clock Buffer

LMH2180 75 MHz Dual Clock Buffer

January 24, 2008

General 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.

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. The LMH2180's rapid recovery after
disable optimizes performance and current consumption.
This part does not use an internal ground reference, thus pro­viding additional system flexibility. The LMH2180 operates
both with single and split supplies.

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. The patent­ed analog circuit of each buffer drives capacitive loads greater
than 20 pF. 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.

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 8-pin LLP solder
bump and no pullback packages minimizing the required PCB
space. National’s advanced packaging offers direct PCB-IC
evaluation via pin access.

Features

(Typical values are: V
otherwise specified.)

Small signal bandwidth 78 MHz

■

Supply voltage range 2.4V to 5V

■

Phase noise (VIN = 1 VPP,

■

fC = 38.4 MHz, Δf = 1kHz)
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

■

8-pin LLP, pin access packaging

■

Temperature range −40°C to 85°C

■

= 2.7V and CL = 10 pF, unless

SUPPLY

-123dBc/Hz

Applications

3G mobile applications

■

WLAN–WiMAX modules

■

TD_SCDMA multi-mode MP3 and camera

■

GSM modules

■

Oscillator modules

■

Typical Application

30024602

© 2008 National Semiconductor Corporation 300246 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/

LMH2180

Distributors for availability and specifications.

Supply Voltages (V+– V−) 5.5V

ESD Tolerance
Human Body (Note 4) 2000V
Machine Model (Note 5) 200V
Charged Device Model 1000V

Junction Temperature (Note 3) +150°C
Soldering Information
Infrared or Convection (35 sec.) 235°C

Operating Ratings (Note 1)

Supply Voltage (V+ – V−)

Temperature Range (Notes 2, 3) −40°C to +85°C
Package Thermal Resistance (Notes 2, 3)

LLP-8 (θJA)

2.4V to 5.0V

217°C/W

Storage Temperature Range −65°C to +150°C

2.7V Electrical Characteristics

Unless otherwise specified, all limits are guaranteed for TJ = 25°C, VDD = 2.7V, VSS = 0V, VCM = 1V, Enable
RL = 30 kΩ, Load is connected to VSS, C

COUPLING

= 10 nF. Boldface limits apply at temperature range extremes of operating

condition. See (Note 2)

Symbol Parameter Conditions Min

(Note 7)

(Note 6)

Frequency Domain Response

SSBW Small Signal Bandwidth VIN = 100 mVPP; −3 dB

LSBW Large Signal Bandwidth VIN = 1.0 VPP; −3 dB

78 MHz

60 MHz

GFN Gain Flatness < 0.1 dB f > 100 kHz 4.9 MHz

Distortion and Noise Performance

φ

n

Phase Noise

VIN = 1 VPP, fC = 38.4 MHz, Δf = 1 kHz

VIN = 1 VPP, fC = 38.4 MHz, Δf = 10 kHz

e

n

I

SOLATION

Input-Referred Voltage Noise

Output to Input

f = 1 MHz, R

f = 1 MHz, R

SOURCE

SOURCE

= 50Ω

= 50Ω

CT Crosstalk Rejection f = 38.4 MHz, VIN = 1 V

PP

−123 dBc/Hz

−132 dBc/Hz

13

84 dB

41 dB

Time Domain Response

t

r

t

f

t

s

OS Overshoot 0.1 VPP Step

SR Slew Rate (Note 8) VIN = 2 V

Rise Time 0.1 VPP Step (10-90%)

Fall Time

Settling Time to 0.1% 1 VPP Step

PP

6 ns

5 ns

120 ns

37 %

106 V/µs

Static DC Performance

I

S

Supply Current Enable

Enable1 = VDD , Enable2 = VSS , No
Load

Enable

= VDD ; No Load

1,2

= VSS ; No Load

1,2

2.3

1.3

30

PSRR Power Supply Rejection Ratio DC (3.0V to 5.0V) 65

64

A

CL

V

OS

TC V

R

OUT

Small Signal Voltage Gain VIN = 0.2 V

Output Offset Voltage

Temperature Coefficient Output

OS

Offset Voltage (Note 9)

PP

0.95 1.0 1.05 V/V

-0.5

2.8 µV/°C

Output Resistance f = 100 kHz 0.6

f = 38.4 MHz 166

= VDD, CL = 10 pF,

1,2

Typ

Max

(Note 7)

2.7

2.9

1.5

1.6

41

46

68 dB

17

18

Units

nV/

mA

mA

μA

mV

Ω

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LMH2180

Symbol Parameter Conditions Min

(Note 7)

Typ

(Note 6)

Max

(Note 7)

Units

Miscellaneous Performance

R

IN

C

IN

Z

IN

V

O

I

SC

V

en_hmin

V

en_lmax

Input Resistance per Buffer Enable = V

Enable = V

Input Capacitance per Buffer Enable = V

Enable = V

Input Impedance f = 38.4 MHz, Enable = V

f = 38.4 MHz, Enable = V

Output Swing Positive VIN = V

DD

DD

SS

DD

SS

DD

SS

2.66

2.65

Output Swing Negative VIN = V

Output Short-Circuit Current
(Notes 10, 11)

SS

Sourcing, VIN = VDD, V

Sinking, VIN = VSS, V

OUT

OUT

= V

= V

DD

SS

−21

−18

Enable High Active Minimum Voltage

Enable Low Inactive Maximum
Voltage

137

137

1.3

1.3

4.5

4.2

2.69

19

−25

23

15

25

1.2

0.6

35

37

kΩ

pF

kΩ

V

mV

mA

V

5V Electrical Characteristics

Unless otherwise specified, all limits are guaranteed for TJ = 25°C, VDD = 5V, VSS = 0V, VCM = 1V, Enable
RL = 30 kΩ, Load is connected to VSS, C

COUPLING

= 10 nF. Boldface limits apply at temperature range extremes of operating

condition. See (Note 2)

Symbol Parameter Conditions Min

(Note 7)

(Note 6)

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

Distortion and Noise Performance

φ

n

e

n

I

SOLATION

Phase Noise

Input-Referred Voltage Noise

Output to Input

VIN = 1 VPP, fC = 38.4 MHz, Δf = 1 kHz

VIN = 1 VPP, fC = 38.4 MHz, Δf = 10 kHz

f = 1 MHz, R

f = 1 MHz, R

SOURCE

SOURCE

= 50Ω

= 50Ω

12

84 dB

CT Crosstalk Rejection f = 38.4 MHz, PIN = 0 dBm 59 dB

Time Domain Response

t

r

t

f

t

s

Rise Time 0.1 VPP Step (10-90%) 6 ns

Fall Time 6 ns

Settling Time to 0.1% 1 VPP Step 70 ns

OS Overshoot 0.1VPP Step 13 %

SR Slew Rate (Note 8) VIN = 2 V

PP

124 V/µs

Static DC Performance

I

S

Supply Current Enable

Enable1 = VDD, Enable2 = VSS ; No
Load

Enable

= VDD ; No Load

1,2

= VSS ; No Load

1,2

3.4

1.8

32

= VDD, CL = 10 pF,

1,2

Typ

(Note 7)

−123

−132

Max

4.0

4.1

2.2

2.3

43

49

Units

dBc/Hz

dBc/Hz

nV/

mA

mA

μA

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Symbol Parameter Conditions Min

PSRR Power Supply Rejection Ratio DC (3.0V to 5.0V) 65

LMH2180

A

CL

V

OS

TC V

Small Signal Voltage Gain VIN = 0.2 V

Output Offset Voltage

Temperature Coefficient Output

OS

PP

Offset Voltage (Note 9)

R

OUT

Output Resistance f = 100 kHz 0.5

f = 38.4 MHz 126

Miscellaneous Performance

R

IN

C

IN

Z

IN

V

O

I

SC

Input Resistance per Buffer Enable = V

Enable = V

Input Capacitance per Buffer Enable = V

Enable = V

DD

SS

DD

SS

Input Impedance f = 38.4 MHz, Enable = V

f = 38.4 MHz, Enable = V

Output Swing Positive VIN = V

Output Swing Negative VIN = V

Output Short-Circuit Current

DD

SS

Sourcing, VIN = VDD, V

OUT

DD

SS

= V

SS

(Notes 10, 11)

V

en_hmin

V

en_lmax

Enable High Active Minimum Voltage

Enable Low Inactive Maximum

Sinking, VIN = VSS, V

OUT

= V

DD

Voltage

(Note 7)

64

Typ

(Note 6)

68 dB

Max

(Note 7)

0.95 1.0 1.05 V/V

−1.4

21

22

2.4 µV/°C

138

138

1.3

1.3

4.3

4.2

4.96

4.95

−80

−62

60

43

1.2

4.99

10

−90

65

35

50

0.6

Units

mV

Ω

kΩ

pF

kΩ

V

mV

mA

V

Note 1: “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.

Note 2: The Electrical Characteristics tables list guaranteed specifications under the listed Recommended Operating Conditions except as otherwise modified
or specified by the Electrical Characteristics Conditions and/or Notes. Typical specifications are estimations only and are not guaranteed.

Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by T
allowable power dissipation is P

Note 4: Human body model, applicable std. JESD22–A114C.

Note 5: Machine model, applicable std. JESD22–A115–A.

Note 6: Typical values represent the most likely parametric norms at TA = +25°C, and at the Recommended Operation Conditions at the time of product

characterization and are not guaranteed.

Note 7: Datasheet min/max specification limits are guaranteed by test or statistical analysis.

Note 8: Slew rate is the average of the rising and falling slew rates.

Note 9: Average Temperature Coefficient is determined by dividing the changing in a parameter at temperature extremes by the total temperature change.

Note 10: 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.

Note 11: Positive current corresponds to current flowing into the device.

DMAX

= (T

− TA) / θJA or the number given in the Absolute Maximum Ratings, whichever is lower.

JMAX

, θJA , and the ambient temperature TA. The maximum

J(MAX)

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Block Diagram

30024601

Pin Descriptions

Pin No. Pin Name Description

1 V

2 IN 1 Input 1

3 IN 2 Input 2

4 ENABLE 2 Enable buffer 2

5 V

6 OUT 2 Output 2

7 OUT 1 Output 1

8 ENABLE 1 Enable buffer 1

DD

SS

Voltage supply connection

Ground connection

LMH2180

Connection Diagram

8-Pin LLP

Top View

30024631

Ordering Information

Package Part Number Package Marking Transport Media NSC Drawing

8-Pin LLP

Solder Bump

8-Pin LLP

No Pullback

LMH2180YD

LMH2180YDX 4.5k Units Tape and Reel

LMH2180SD

LMH2180SDX 4.5 Units Tape and Reel

LMH2180YD

LMH2180SD

1k Units Tape and Reel

1k Units Tape and Reel

YDA08A

SDA08A

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