LMH6642EP/LMH6643EP/LMH6644EP
Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail
Output Amplifiers
General Description
The LMH664XEP family true single supply voltage feedback
amplifiers offer high speed (130MHz), low distortion
(−62dBc), and exceptionally high output current (approxi-
mately 75mA) at low cost and with reduced power consump-
tion when compared against existing devices with similar
performance.
Input common mode voltage range extends to 0.5V below V
−
and 1V from V
+
. Output voltage range extends to within
40mV of either supply rail, allowing wide dynamic range
especially desirable in low voltage applications. The output
stage is capable of approximately 75mA in order to drive
heavy loads. Fast output Slew Rate (130V/µs) ensures large
peak-to-peak output swings can be maintained even at
higher speeds, resulting in exceptional full power bandwidth
of 40MHz with a 3V supply. These characteristics, along with
low cost, are ideal features for a multitude of industrial and
commercial applications.
Careful attention has been paid to ensure device stability
under all operating voltages and modes. The result is a very
well behaved frequency response characteristic (0.1dB gain
flatness up the 12MHz under 150Ωload and A
V
= +2) with
minimal peaking (typically 2dB maximum) for any gain set-
ting and under both heavy and light loads. This along with
fast settling time (68ns) and low distortion allows the device
to operate well in ADC buffer, and high frequency filter
applications as well as other applications.
This device family offers professional quality video perfor-
mance with low DG (0.01%) and DP (0.01˚) characteristics.
Differential Gain and Differential Phase characteristics are
also well maintained under heavy loads (150Ω) and through-
out the output voltage range. The LMH664XEP family is
offered in single (LMH6642EP), dual (LMH6643EP), and
quad (LMH6644EP) options. See ordering information for
packages offered.
ENHANCED PLASTIC
•Extended Temperature Performance of −40˚C to +85˚C
•Baseline Control - Single Fab & Assembly Site
•Process Change Notification (PCN)
•Qualification & Reliability Data
•Solder (PbSn) Lead Finish is standard
•Enhanced Diminishing Manufacturing Sources (DMS)
Support
Features
(V
S
=±5V, T
A
= 25˚C, R
L
=2kΩ,A
V
= +1. Typical values
unless specified).
n−3dB BW (A
V
= +1) 130MHz
nSupply voltage range 2.7V to 12.8V
nSlew rate (Note 11), (A
V
= −1) 130V/µs
nSupply current (no load) 2.7mA/amp
nOutput short circuit current +115mA/−145mA
nLinear output current ±75mA
nInput common mode volt. 0.5V beyond V
−
, 1V from V
+
nOutput voltage swing 40mV from rails
nInput voltage noise (100kHz) 17nV/
nInput current noise (100kHz) 0.9pA/
nTHD (5MHz, R
L
=2kΩ,V
O
=2V
PP
,A
V
= +2) −62dBc
nSettling time 68ns
nFully characterized for 3V, 5V, and ±5V
nOverdrive recovery 100ns
nOutput short circuit protected (Note 14)
nNo output phase reversal with CMVR exceeded
Applications
nSelected Military Applications
nSelected Avionics Applications
Ordering Information
PART NUMBER VID PART NUMBER NS PACKAGE NUMBER (Note 3)
LMH6642MFXEP V62/04625-01 MF05A
LMH6643MAXEP V62/04625-02 M08A
LMH6644MAXEP V62/04625-03 M14A
(Notes 1, 2) TBD TBD
Note 1: For the following (Enhanced Plastic) versions, check for availability: LMH6642MAEP, LMH6642MAXEP, LMH6642MFEP, LMH6643MAEP,
LMH6643MMEP, LMH6643MMXEP, LMH6644MAEP, LMH6644MTEP, LMH6644MTXEP. Parts listed with an "X" are provided in Tape & Reel and parts
without an "X" are in Rails.
Note 2: FOR ADDITIONAL ORDERING AND PRODUCT INFORMATION, PLEASE VISIT THE ENHANCED PLASTIC WEB SITE AT: www.national.com/
mil
Note 3: Refer to package details under Physical Dimensions
July 2004
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail
Output Amplifiers
© 2004 National Semiconductor Corporation DS200894 www.national.com
Absolute Maximum Ratings (Note 4)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance 2KV (Note 5)
200V (Note 12)
V
IN
Differential ±2.5V
Output Short Circuit Duration (Note 6), (Note 14)
Supply Voltage (V
+
-V
−
) 13.5V
Voltage at Input/Output pins V
+
+0.8V, V
−
−0.8V
Input Current ±10mA
Storage Temperature Range −65˚C to +150˚C
Junction Temperature (Note 7) +150˚C
Soldering Information
Infrared or Convection Reflow(20 sec) 235˚C
Wave Soldering Lead Temp.(10 sec) 260˚C
Operating Ratings (Note 4)
Supply Voltage (V
+
–V
−
) 2.7V to 12.8V
Junction Temperature Range (Note 7) −40˚C to +85˚C
Package Thermal Resistance (Note 7) (θ
JA
)
SOT23-5 265˚C/W
SOIC-8 190˚C/W
MSOP-8 235˚C/W
SOIC-14 145˚C/W
TSSOP-14 155˚C/W
3V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at T
J
= 25˚C, V
+
= 3V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=2kΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min
(Note 9)
Typ
(Note 8)
Max
(Note 9)
Units
BW −3dB BW A
V
= +1, V
OUT
= 200mV
PP
80 115 MHz
A
V
= +2, −1, V
OUT
= 200mV
PP
46
BW
0.1dB
0.1dB Gain Flatness A
V
= +2, R
L
= 150Ωto V+/2,
R
L
= 402Ω,V
OUT
= 200mV
PP
19 MHz
PBW Full Power Bandwidth A
V
= +1, −1dB, V
OUT
=1V
PP
40 MHz
e
n
Input-Referred Voltage Noise f = 100kHz 17 nV/
f = 1kHz 48
i
n
Input-Referred Current Noise f = 100kHz 0.90 pA/
f = 1kHz 3.3
THD Total Harmonic Distortion f = 5MHz, V
O
=2V
PP
,A
V
= −1,
R
L
= 100Ωto V
+
/2
−48 dBc
DG Differential Gain V
CM
= 1V, NTSC, A
V
=+2
R
L
=150Ωto V
+
/2
0.17
%
R
L
=1kΩto V
+
/2 0.03
DP Differential Phase V
CM
= 1V, NTSC, A
V
=+2
R
L
=150Ωto V
+
/2
0.05
deg
R
L
=1kΩto V
+
/2 0.03
CT Rej. Cross-Talk Rejection f = 5MHz, Receiver:
R
f
=R
g
= 510Ω,A
V
=+2
47 dB
T
S
Settling Time V
O
=2V
PP
,±0.1%, 8pF Load,
V
S
=5V
68 ns
SR Slew Rate (Note 11) A
V
= −1, V
I
=2V
PP
90 120 V/µs
V
OS
Input Offset Voltage ±1±5
±7
mV
TC V
OS
Input Offset Average Drift (Note 15) ±5 µV/˚C
I
B
Input Bias Current (Note 10) −1.50 −2.60
−3.25 µA
I
OS
Input Offset Current 20 800
1000 nA
R
IN
Common Mode Input
Resistance
3MΩ
C
IN
Common Mode Input
Capacitance
2pF
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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3V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for at T
J
= 25˚C, V
+
= 3V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=2kΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min
(Note 9)
Typ
(Note 8)
Max
(Note 9)
Units
CMVR Input Common-Mode Voltage
Range
CMRR ≥50dB −0.5 −0.2
−0.1 V
1.8
1.6
2.0
CMRR Common Mode Rejection
Ratio
V
CM
Stepped from 0V to 1.5V 72 95 dB
A
VOL
Large Signal Voltage Gain V
O
= 0.5V to 2.5V
R
L
=2kΩto V
+
/2
80
75
96
dB
V
O
= 0.5V to 2.5V
R
L
= 150Ωto V
+
/2
74
70
82
V
O
Output Swing
High
R
L
=2kΩto V
+
/2, V
ID
= 200mV 2.90 2.98 V
R
L
= 150Ωto V
+
/2, V
ID
= 200mV 2.80 2.93
Output Swing
Low
R
L
=2kΩto V
+
/2, V
ID
= −200mV 25 75 mV
R
L
= 150Ωto V
+
/2, V
ID
= −200mV 75 150
I
SC
Output Short Circuit Current Sourcing to V
+
/2
V
ID
= 200mV (Note 13)
50
35
95
mA
Sinking to V
+
/2
V
ID
= −200mV (Note 13)
55
40
110
I
OUT
Output Current V
OUT
= 0.5V from either supply ±65 mA
+PSRR Positive Power Supply
Rejection Ratio
V
+
= 3.0V to 3.5V, V
CM
= 1.5V 75 85 dB
I
S
Supply Current (per channel) No Load 2.70 4.00
4.50 mA
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at T
J
= 25˚C, V
+
= 5V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=2kΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min
(Note 9)
Typ
(Note 8)
Max
(Note 9)
Units
BW −3dB BW A
V
= +1, V
OUT
= 200mV
PP
90 120 MHz
A
V
= +2, −1, V
OUT
= 200mV
PP
46
BW
0.1dB
0.1dB Gain Flatness A
V
= +2, R
L
= 150Ωto V+/2,
R
f
= 402Ω,V
OUT
= 200mV
PP
15 MHz
PBW Full Power Bandwidth A
V
= +1, −1dB, V
OUT
=2V
PP
22 MHz
e
n
Input-Referred Voltage Noise f = 100kHz 17 nV/
f = 1kHz 48
i
n
Input-Referred Current Noise f = 100kHz 0.90 pA/
f = 1kHz 3.3
THD Total Harmonic Distortion f = 5MHz, V
O
=2V
PP
,A
V
= +2 −60 dBc
DG Differential Gain NTSC, A
V
=+2
R
L
=150Ωto V
+
/2 0.16 %
R
L
=1kΩto V
+
/2 0.05
DP Differential Phase NTSC, A
V
=+2
R
L
=150Ωto V
+
/2 0.05 deg
R
L
=1kΩto V
+
/2 0.01
CT Rej. Cross-Talk Rejection f = 5MHz, Receiver:
R
f
=R
g
= 510Ω,A
V
=+2 47 dB
T
S
Settling Time V
O
=2V
PP
,±0.1%, 8pF Load 68 ns
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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5V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for at T
J
= 25˚C, V
+
= 5V, V
−
= 0V, V
CM
=V
O
=V
+
/2, and R
L
=2kΩto V
+
/2.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min
(Note 9)
Typ
(Note 8)
Max
(Note 9)
Units
SR Slew Rate (Note 11) A
V
= −1, V
I
=2V
PP
95 125 V/µs
V
OS
Input Offset Voltage ±1±5
±7mV
TC V
OS
Input Offset Average Drift (Note 15) ±5 µV/˚C
I
B
Input Bias Current (Note 10) −1.70 −2.60
−3.25 µA
I
OS
Input Offset Current 20 800
1000 nA
R
IN
Common Mode Input
Resistance 3MΩ
C
IN
Common Mode Input
Capacitance 2pF
CMVR Input Common-Mode Voltage
Range
CMRR ≥50dB −0.5 −0.2
−0.1 V
3.8
3.6 4.0
CMRR Common Mode Rejection
Ratio
V
CM
Stepped from 0V to 3.5V 72 95 dB
A
VOL
Large Signal Voltage Gain V
O
= 0.5V to 4.50V
R
L
=2kΩto V
+
/2
86
82 98
dB
V
O
= 0.5V to 4.25V
R
L
= 150Ωto V
+
/2
76
72 82
V
O
Output Swing
High
R
L
=2kΩto V
+
/2, V
ID
= 200mV 4.90 4.98 V
R
L
= 150Ωto V
+
/2, V
ID
= 200mV 4.65 4.90
Output Swing
Low
R
L
=2kΩto V
+
/2, V
ID
= −200mV 25 100 mV
R
L
= 150Ωto V
+
/2, V
ID
= −200mV 100 150
I
SC
Output Short Circuit Current Sourcing to V
+
/2
V
ID
= 200mV (Note 13)
55
40 115
mA
Sinking to V
+
/2
V
ID
= −200mV (Note 13)
70
55 140
I
OUT
Output Current V
O
= 0.5V from either supply ±70 mA
+PSRR Positive Power Supply
Rejection Ratio
V
+
= 4.0V to 6V 79 90 dB
I
S
Supply Current (per channel) No Load 2.70 4.25
5.00 mA
±5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at T
J
= 25˚C, V
+
= 5V, V
−
= −5V, V
CM
=V
O
= 0V and R
L
=2kΩto ground.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min
(Note 9)
Typ
(Note 8)
Max
(Note 9)
Units
BW −3dB BW A
V
= +1, V
OUT
= 200mV
PP
95 130 MHz
A
V
= +2, −1, V
OUT
= 200mV
PP
46
BW
0.1dB
0.1dB Gain Flatness A
V
= +2, R
L
= 150Ωto V+/2,
R
f
= 806Ω,V
OUT
= 200mV
PP
12 MHz
PBW Full Power Bandwidth A
V
= +1, −1dB, V
OUT
=2V
PP
24 MHz
e
n
Input-Referred Voltage Noise f = 100kHz 17 nV/
f = 1kHz 48
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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±5V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for at T
J
= 25˚C, V
+
= 5V, V
−
= −5V, V
CM
=V
O
= 0V and R
L
=2kΩto ground.
Boldface limits apply at the temperature extremes.
Symbol Parameter Conditions Min
(Note 9)
Typ
(Note 8)
Max
(Note 9)
Units
i
n
Input-Referred Current Noise f = 100kHz 0.90 pA/
f = 1kHz 3.3
THD Total Harmonic Distortion f = 5MHz, V
O
=2V
PP
,A
V
= +2 −62 dBc
DG Differential Gain NTSC, A
V
=+2
R
L
=150Ωto V
+
/2 0.15 %
R
L
=1kΩto V
+
/2 0.01
DP Differential Phase NTSC, A
V
=+2
R
L
=150Ωto V
+
/2 0.04 deg
R
L
=1kΩto V
+
/2 0.01
CT Rej. Cross-Talk Rejection f = 5MHz, Receiver:
R
f
=R
g
= 510Ω,A
V
=+2 47 dB
T
S
Settling Time V
O
=2V
PP
,±0.1%, 8pF Load,
V
S
=5V 68 ns
SR Slew Rate (Note 11) A
V
= −1, V
I
=2V
PP
100 135 V/µs
V
OS
Input Offset Voltage ±1±5
±7mV
TC V
OS
Input Offset Average Drift (Note 15) ±5 µV/˚C
I
B
Input Bias Current (Note 10) −1.60 −2.60
−3.25 µA
I
OS
Input Offset Current 20 800
1000 nA
R
IN
Common Mode Input
Resistance 3MΩ
C
IN
Common Mode Input
Capacitance 2pF
CMVR Input Common-Mode Voltage
Range
CMRR ≥50dB −5.5 −5.2
−5.1 V
3.8
3.6 4.0
CMRR Common Mode Rejection
Ratio
V
CM
Stepped from −5V to 3.5V 74 95 dB
A
VOL
Large Signal Voltage Gain V
O
= −4.5V to 4.5V,
R
L
=2kΩ
88
84 96
dB
V
O
= −4.0V to 4.0V,
R
L
= 150Ω
78
74 82
V
O
Output Swing
High
R
L
=2kΩ,V
ID
= 200mV 4.90 4.96 V
R
L
= 150Ω,V
ID
= 200mV 4.65 4.80
Output Swing
Low
R
L
=2kΩ,V
ID
= −200mV −4.96 −4.90 V
R
L
= 150Ω,V
ID
= −200mV −4.80 −4.65
I
SC
Output Short Circuit Current Sourcing to Ground
V
ID
= 200mV (Note 13)
60
35 115
mA
Sinking to Ground
V
ID
= −200mV (Note 13)
85
65 145
I
OUT
Output Current V
O
= 0.5V from either supply ±75 mA
PSRR Power Supply Rejection Ratio (V
+
,V
−
) = (4.5V, −4.5V) to (5.5V,
−5.5V) 78 90 dB
I
S
Supply Current (per channel) No Load 2.70 4.50
5.50 mA
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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±5V Electrical Characteristics (Continued)
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 specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.
Note 5: Human body model, 1.5kΩin series with 100pF.
Note 6: Applies to both single-supply and split-supply operation. Continuous short circuit operation at elevated ambient temperature can result in exceeding the
maximum allowed junction temperature of 150˚C.
Note 7: The maximum power dissipation is a function of TJ(MAX),θJA, and TA. The maximum allowable power dissipation at any ambient temperature is
PD=(T
J(MAX) -T
A)/ θJA . All numbers apply for packages soldered directly onto a PC board.
Note 8: Typical values represent the most likely parametric norm.
Note 9: All limits are guaranteed by testing or statistical analysis.
Note 10: Positive current corresponds to current flowing into the device.
Note 11: Slew rate is the average of the rising and falling slew rates.
Note 12: Machine Model, 0Ωin series with 200pF.
Note 13: Short circuit test is a momentary test. See Note 14.
Note 14: Output short circuit duration is infinite for VS<6V at room temperature and below. For VS>6V, allowable short circuit duration is 1.5ms.
Note 15: Offset voltage average drift determined by dividing the change in VOS at temperature extremes by the total temperature change.
Connection Diagrams
SOT23-5 (LMH6642) SOIC-8 (LMH6642)
SOIC-8 and MSOP-8
(LMH6643)
20089461
Top View 20089462
Top View 20089463
Top View
SOIC-14 and TSSOP-14
(LMH6644)
20089468
Top View
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless oth-
erwise specified.
Closed Loop Frequency Response for Various Supplies Closed Loop Gain vs. Frequency for Various Gain
20089457
20089451
Closed Loop Gain vs. Frequency for Various Gain
Closed Loop Frequency Response for Various
Temperature
20089435
20089450
Closed Loop Gain vs. Frequency for Various Supplies
Closed Loop Frequency Response for Various
Temperature
20089448 20089434
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
Large Signal Frequency Response
Closed Loop Small Signal Frequency Response for
Various Supplies
20089447 20089446
Closed Loop Frequency Response for Various Supplies ±0.1dB Gain Flatness for Various Supplies
20089444
20089445
V
OUT
(V
PP
) for THD <0.5% V
OUT
(V
PP
) for THD <0.5%
20089409 20089408
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
V
OUT
(V
PP
) for THD <0.5% Open Loop Gain/Phase for Various Temperature
20089410 20089432
Open Loop Gain/Phase for Various Temperature HD2 (dBc) vs. Output Swing
20089433
20089414
HD3 (dBc) vs. Output Swing HD2 vs. Output Swing
20089415 20089404
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
HD3 vs. Output Swing THD (dBc) vs. Output Swing
20089405 20089406
Settling Time vs. Input Step Amplitude
(Output Slew and Settle Time) Input Noise vs. Frequency
20089413 20089412
V
OUT
from V
+
vs. I
SOURCE
V
OUT
from V
−
vs. I
SINK
20089418 20089419
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
V
OUT
from V
+
vs. I
SOURCE
V
OUT
from V
−
vs. I
SINK
20089416 20089417
Swing vs. V
S
Short Circuit Current (to V
S
/2) vs. V
S
20089429 20089431
Output Sinking Saturation Voltage vs. I
OUT
Output Sourcing Saturation Voltage vs. I
OUT
20089420 20089401
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
Closed Loop Output Impedance vs. Frequency A
V
= +1 PSRR vs. Frequency
20089402 20089403
CMRR vs. Frequency
Crosstalk Rejection vs. Frequency
(Output to Output)
20089407 20089411
V
OS
vs. V
OUT
(Typical Unit) V
OS
vs. V
CM
(Typical Unit)
20089430 20089427
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
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Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
V
OS
vs. V
S
(for 3 Representative Units) V
OS
vs. V
S
(for 3 Representative Units)
20089422 20089423
V
OS
vs. V
S
(for 3 Representative Units) I
B
vs. V
S
20089424 20089425
I
OS
vs. V
S
I
S
vs. V
CM
20089426 20089428
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com13
Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
I
S
vs. V
S
Small Signal Step Response
20089421
20089453
Large Signal Step Response Large Signal Step Response
20089441 20089439
Small Signal Step Response Small Signal Step Response
20089456 20089436
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com 14
Typical Performance Characteristics At T
J
= 25˚C, V
+
= +5, V
−
= −5V, R
F
=R
L
=2kΩ. Unless
otherwise specified. (Continued)
Small Signal Step Response Small Signal Step Response
20089452 20089438
Large Signal Step Response Large Signal Step Response
20089437 20089454
Large Signal Step Response
20089460
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com15
Application Notes
CIRCUIT DESCRIPTION
The LMH664XEP family is based on National Semiconduc-
tor’s proprietary VIP10 dielectrically isolated bipolar process.
This device family architecture features the following:
•Complimentary bipolar devices with exceptionally high f
t
(∼8GHz) even under low supply voltage (2.7V) and low
bias current.
•A class A-B “turn-around” stage with improved noise,
offset, and reduced power dissipation compared to simi-
lar speed devices (patent pending).
•Common Emitter push-push output stage capable of
75mA output current (at 0.5V from the supply rails) while
consuming only 2.7mA of total supply current per chan-
nel. This architecture allows output to reach within milli-
volts of either supply rail.
•Consistent performance from any supply voltage (3V-
10V) with little variation with supply voltage for the most
important specifications (e.g. BW, SR, I
OUT
, etc.)
•Significant power saving (∼40%) compared to competi-
tive devices on the market with similar performance.
Application Hints
This Op Amp family is a drop-in replacement for the AD805X
family of high speed Op Amps in most applications. In addi-
tion, the LMH664XEP will typically save about 40% on power
dissipation, due to lower supply current, when compared to
competition. All AD805X family’s guaranteed parameters are
included in the list of LMH664XEP guaranteed specifications
in order to ensure equal or better level of performance.
However, as in most high performance parts, due to subtle-
ties of applications, it is strongly recommended that the
performance of the part to be evaluated is tested under
actual operating conditions to ensure full compliance to all
specifications.
With 3V supplies and a common mode input voltage range
that extends 0.5V below V
−
, the LMH664XEP find applica-
tions in low voltage/low power applications. Even with 3V
supplies, the −3dB BW (@A
V
= +1) is typically 115MHz with
a tested limit of 80MHz. Production testing guarantees that
process variations with not compromise speed. High fre-
quency response is exceptionally stable confining the typical
-3dB BW over the industrial temperature range to ±2.5%.
As can be seen from the typical performance plots, the
LMH664XEP output current capability (∼75mA) is enhanced
compared to AD805X. This enhancement, increases the
output load range, adding to the LMH664XEP’s versatility.
Because of the LMH664XEP’s high output current capability
attention should be given to device junction temperature in
order not to exceed the Absolute Maximum Rating.
This device family was designed to avoid output phase
reversal. With input overdrive, the output is kept near supply
rail (or as closed to it as mandated by the closed loop gain
setting and the input voltage). See Figure 1:
However, if the input voltage range of −0.5V to 1V from V
+
is
exceeded by more than a diode drop, the internal ESD
protection diodes will start to conduct.The current in the
diodes should be kept at or below 10mA.
Output overdrive recovery time is less than 100ns as can be
seen from Figure 2 plot:
20089442
FIGURE 1. Input and Output Shown with CMVR
Exceeded
20089443
FIGURE 2. Overload Recovery Waveform
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com 16
Application Notes (Continued)
SINGLE SUPPLY, LOW POWER PHOTODIODE
AMPLIFIER
The circuit shown in Figure 3 is used to amplify the current
from a photo-diode into a voltage output. In this circuit, the
emphasis is on achieving high bandwidth and the transim-
pedance gain setting is kept relatively low. Because of its
high slew rate limit and high speed, the LMH664XEP family
lends itself well to such an application.
This circuit achieves approximately 1V/mA of transimped-
ance gain and capable of handling up to 1mA
pp
from the
photodiode. Q1, in a common base configuration, isolates
the high capacitance of the photodiode (C
d
) from the Op
Amp input in order to maximize speed. Input is AC coupled
through C1 to ease biasing and allow single supply opera-
tion. With 5V single supply, the device input/output is shifted
to near half supply using a voltage divider from V
CC
. Note
that Q1 collector does not have any voltage swing and the
Miller effect is minimized. D1, tied to Q1 base, is for tem-
perature compensation of Q1’s bias point. Q1 collector cur-
rent was set to be large enough to handle the peak-to-peak
photodiode excitation and not too large to shift the U1 output
too far from mid-supply.
No matter how low an R
f
is selected, there is a need for C
f
in
order to stabilize the circuit. The reason for this is that the Op
Amp input capacitance and Q1 equivalent collector capaci-
tance together (C
IN
) will cause additional phase shift to the
signal fed back to the inverting node. C
f
will function as a
zero in the feedback path counter-acting the effect of the C
IN
and acting to stabilized the circuit. By proper selection of C
f
such that the Op Amp open loop gain is equal to the inverse
of the feedback factor at that frequency, the response is
optimized with a theoretical 45˚ phase margin.
(1)
where GBWP is the Gain Bandwidth Product of the Op Amp
Optimized as such, the I-V converter will have a theoretical
pole, f
p
, at:
(2)
With Op Amp input capacitance of 3pF and an estimate for
Q1 output capacitance of about 3pF as well, C
IN
= 6pF. From
the typical performance plots, LMH6642EP/6643EP family
GBWP is approximately 57MHz. Therefore, with R
f
= 1k,
from Equation 1 and 2 above.
C
f
=∼4.1pF, and f
p
= 39MHz
20089464
FIGURE 3. Single Supply Photodiode I-V Converter
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com17
Application Notes (Continued)
For this example, optimum C
f
was empirically determined to
be around 5pF. This time domain response is shown in
Figure 4 below showing about 9ns rise/fall times, corre-
sponding to about 39MHz for f
p
. The overall supply current
from the +5V supply is around 5mA with no load.
PRINTED CIRCUIT BOARD LAYOUT AND COMPONENT
VALUES SECTIONS
Generally, a good high frequency layout will keep power
supply and ground traces away from the inverting input and
output pins. Parasitic capacitances on these nodes to
ground will cause frequency response peaking and possible
circuit oscillations (see Application Note OA-15 for more
information). National Semiconductor suggests the following
evaluation boards as a guide for high frequency layout and
as an aid in device testing and characterization:
Device Package Evaluation
Board PN
LMH6642MF SOT23-5 CLC730068
LMH6642MF 8-Pin SOIC CLC730027
LMH6643MA 8-Pin SOIC CLC730036
LMH6643MA 8-Pin MSOP CLC730123
LMH6644MA 14-Pin SOIC CLC730031
LMH6644MA 14-Pin TSSOP CLC730131
These free evaluation boards are shipped when a device
sample request is placed with National Semiconductor.
Another important parameter in working with high speed/
high performance amplifiers, is the component values selec-
tion. Choosing external resistors that are large in value will
effect the closed loop behavior of the stage because of the
interaction of these resistors with parasitic capacitances.
These capacitors could be inherent to the device or a by-
product of the board layout and component placement. Ei-
ther way, keeping the resistor values lower, will diminish this
interaction to a large extent. On the other hand, choosing
very low value resistors could load down nodes and will
contribute to higher overall power dissipation.
20089465
FIGURE 4. Converter Step Response (1V
PP
, 20 ns/DIV)
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com 18
Physical Dimensions inches (millimeters) unless otherwise noted
5-Pin SOT23
NS Package Number MF05A
8-Pin SOIC
NS Package Number M08A
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com19
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Pin MSOP
NS Package Number MUA08A
14-Pin SOIC
NS Package Number M14A
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic
www.national.com 20
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
14-Pin TSSOP
NS Package Number MTC14
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NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL
COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:
1. Life support devices or systems are devices or
systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and
whose failure to perform when properly used in
accordance with instructions for use provided in the
labeling, can be reasonably expected to result in a
significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
the life support device or system, or to affect its
safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products
Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification
(CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2.
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Support Center
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
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Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
LMH6642EP/LMH6643EP/LMH6644EP Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail
Output Amplifiers
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
