LMH6642EP [NSC]
Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers; 增强型塑料，低功耗，为130MHz ， 75毫安轨到轨输出放大器
| 型号： | LMH6642EP |
| 厂家： | 
National Semiconductor |
| 描述： | Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail Output Amplifiers |
| 文件： | 总21页 (文件大小：961K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
July 2004
LMH6642EP/LMH6643EP/LMH6644EP
Enhanced Plastic Low Power, 130MHz, 75mA Rail-to-Rail
Output Amplifiers
ENHANCED PLASTIC
General Description
•
•
•
•
•
•
Extended Temperature Performance of −40˚C to +85˚C
Baseline Control - Single Fab & Assembly Site
Process Change Notification (PCN)
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.
Qualification & Reliability Data
Solder (PbSn) Lead Finish is standard
Enhanced Diminishing Manufacturing Sources (DMS)
Support
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.
Features
(VS
=
5V, TA = 25˚C, RL = 2kΩ, AV = +1. Typical values
unless specified).
n −3dB BW (AV = +1)
130MHz
2.7V to 12.8V
130V/µs
n Supply voltage range
n Slew rate (Note 11), (AV = −1)
n Supply current (no load)
n Output short circuit current
n Linear output current
n Input common mode volt. 0.5V beyond V−, 1V from V+
n Output voltage swing
n Input voltage noise (100kHz)
n Input current noise (100kHz)
n THD (5MHz, RL = 2kΩ, VO = 2VPP, AV = +2)
n Settling time
n Fully characterized for 3V, 5V, and 5V
n Overdrive recovery
n Output short circuit protected (Note 14)
n No output phase reversal with CMVR exceeded
2.7mA/amp
+115mA/−145mA
75mA
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 150Ω load and AV = +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.
40mV from rails
17nV/
0.9pA/
−62dBc
68ns
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.
100ns
Applications
n Selected Military Applications
n Selected Avionics Applications
Ordering Information
PART NUMBER
LMH6642MFXEP
LMH6643MAXEP
LMH6644MAXEP
(Notes 1, 2)
VID PART NUMBER
V62/04625-01
V62/04625-02
V62/04625-03
TBD
NS PACKAGE NUMBER (Note 3)
MF05A
M08A
M14A
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
© 2004 National Semiconductor Corporation
DS200894
www.national.com
Absolute Maximum Ratings (Note 4)
Infrared or Convection Reflow(20 sec)
Wave Soldering Lead Temp.(10 sec)
235˚C
260˚C
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Operating Ratings (Note 4)
Supply Voltage (V+ – V−)
ESD Tolerance
2KV (Note 5)
200V (Note 12)
2.5V
2.7V to 12.8V
Junction Temperature Range (Note 7)
−40˚C to +85˚C
VIN Differential
Package Thermal Resistance (Note 7) (θJA
)
Output Short Circuit Duration
Supply Voltage (V+ - V−)
Voltage at Input/Output pins
Input Current
(Note 6), (Note 14)
SOT23-5
SOIC-8
265˚C/W
190˚C/W
235˚C/W
145˚C/W
155˚C/W
13.5V
V+ +0.8V, V− −0.8V
10mA
MSOP-8
SOIC-14
TSSOP-14
Storage Temperature Range
Junction Temperature (Note 7)
Soldering Information
−65˚C to +150˚C
+150˚C
3V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 3V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2.
Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 9)
80
Typ
(Note 8)
115
Max
(Note 9)
Units
BW
−3dB BW
AV = +1, VOUT = 200mVPP
AV = +2, −1, VOUT = 200mVPP
AV = +2, RL = 150Ω to V+/2,
RL = 402Ω, VOUT = 200mVPP
AV = +1, −1dB, VOUT = 1VPP
f = 100kHz
MHz
MHz
46
BW0.1dB
0.1dB Gain Flatness
19
PBW
en
Full Power Bandwidth
40
17
MHz
Input-Referred Voltage Noise
nV/
pA/
dBc
f = 1kHz
48
in
Input-Referred Current Noise
Total Harmonic Distortion
Differential Gain
f = 100kHz
0.90
3.3
−48
f = 1kHz
THD
DG
f = 5MHz, VO = 2VPP, AV = −1,
RL = 100Ω to V+/2
VCM = 1V, NTSC, AV = +2
RL =150Ω to V+/2
RL =1kΩ to V+/2
0.17
%
0.03
0.05
DP
Differential Phase
VCM = 1V, NTSC, AV = +2
RL =150Ω to V+/2
RL =1kΩ to V+/2
deg
dB
ns
0.03
47
CT Rej.
TS
Cross-Talk Rejection
Settling Time
f = 5MHz, Receiver:
Rf = Rg = 510Ω, AV = +2
VO = 2VPP
VS = 5V
,
0.1%, 8pF Load,
68
SR
Slew Rate (Note 11)
Input Offset Voltage
AV = −1, VI = 2VPP
90
120
1
V/µs
mV
VOS
5
7
TC VOS
IB
Input Offset Average Drift
Input Bias Current
(Note 15)
(Note 10)
5
µV/˚C
µA
−1.50
−2.60
−3.25
800
IOS
RIN
CIN
Input Offset Current
20
3
nA
1000
Common Mode Input
Resistance
MΩ
Common Mode Input
Capacitance
2
pF
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2
3V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 3V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2.
Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 9)
Typ
(Note 8)
−0.5
Max
(Note 9)
−0.2
Units
CMVR
Input Common-Mode Voltage
Range
CMRR ≥ 50dB
−0.1
V
1.8
1.6
72
2.0
95
96
82
CMRR
AVOL
Common Mode Rejection
Ratio
VCM Stepped from 0V to 1.5V
dB
Large Signal Voltage Gain
VO = 0.5V to 2.5V
RL = 2kΩ to V+/2
80
75
dB
VO = 0.5V to 2.5V
RL = 150Ω to V+/2
74
70
VO
Output Swing
High
RL = 2kΩ to V+/2, VID = 200mV
RL = 150Ω to V+/2, VID = 200mV
RL = 2kΩ to V+/2, VID = −200mV
RL = 150Ω to V+/2, VID = −200mV
Sourcing to V+/2
2.90
2.80
2.98
2.93
25
V
Output Swing
Low
75
mV
75
150
ISC
Output Short Circuit Current
50
35
55
40
95
VID = 200mV (Note 13)
Sinking to V+/2
mA
110
VID = −200mV (Note 13)
VOUT = 0.5V from either supply
V+ = 3.0V to 3.5V, VCM = 1.5V
IOUT
Output Current
65
85
mA
dB
+PSRR
Positive Power Supply
Rejection Ratio
75
IS
Supply Current (per channel)
No Load
2.70
4.00
mA
4.50
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2.
Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 9)
90
Typ
(Note 8)
120
Max
(Note 9)
Units
BW
−3dB BW
AV = +1, VOUT = 200mVPP
AV = +2, −1, VOUT = 200mVPP
AV = +2, RL = 150Ω to V+/2,
Rf = 402Ω, VOUT = 200mVPP
AV = +1, −1dB, VOUT = 2VPP
f = 100kHz
MHz
46
BW0.1dB
0.1dB Gain Flatness
15
MHz
MHz
PBW
en
Full Power Bandwidth
22
17
Input-Referred Voltage Noise
nV/
pA/
dBc
f = 1kHz
48
in
Input-Referred Current Noise
f = 100kHz
0.90
3.3
−60
f = 1kHz
THD
DG
Total Harmonic Distortion
Differential Gain
f = 5MHz, VO = 2VPP, AV = +2
NTSC, AV = +2
RL =150Ω to V+/2
RL =1kΩ to V+/2
0.16
0.05
0.05
0.01
47
%
DP
Differential Phase
NTSC, AV = +2
RL =150Ω to V+/2
deg
RL =1kΩ to V+/2
CT Rej.
TS
Cross-Talk Rejection
Settling Time
f = 5MHz, Receiver:
Rf = Rg = 510Ω, AV = +2
dB
ns
VO = 2VPP
,
0.1%, 8pF Load
68
3
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5V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2, and RL = 2kΩ to V+/2.
Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 9)
95
Typ
(Note 8)
125
Max
(Note 9)
Units
SR
Slew Rate (Note 11)
Input Offset Voltage
AV = −1, VI = 2VPP
V/µs
mV
VOS
5
1
5
7
TC VOS
IB
Input Offset Average Drift
Input Bias Current
(Note 15)
(Note 10)
µV/˚C
µA
−2.60
−3.25
800
−1.70
IOS
Input Offset Current
20
3
nA
1000
RIN
Common Mode Input
Resistance
MΩ
CIN
Common Mode Input
Capacitance
pF
2
CMVR
Input Common-Mode Voltage
Range
CMRR ≥ 50dB
−0.2
−0.5
4.0
95
98
82
−0.1
V
3.8
3.6
CMRR
AVOL
Common Mode Rejection
Ratio
VCM Stepped from 0V to 3.5V
dB
72
Large Signal Voltage Gain
VO = 0.5V to 4.50V
RL = 2kΩ to V+/2
86
82
dB
VO = 0.5V to 4.25V
RL = 150Ω to V+/2
76
72
VO
Output Swing
High
RL = 2kΩ to V+/2, VID = 200mV
RL = 150Ω to V+/2, VID = 200mV
RL = 2kΩ to V+/2, VID = −200mV
RL = 150Ω to V+/2, VID = −200mV
Sourcing to V+/2
4.90
4.65
4.98
4.90
25
V
Output Swing
Low
100
150
mV
100
ISC
Output Short Circuit Current
55
40
70
55
115
VID = 200mV (Note 13)
Sinking to V+/2
mA
140
70
VID = −200mV (Note 13)
VO = 0.5V from either supply
V+ = 4.0V to 6V
IOUT
Output Current
mA
dB
+PSRR
Positive Power Supply
Rejection Ratio
79
90
IS
Supply Current (per channel)
No Load
4.25
2.70
mA
5.00
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = −5V, VCM = VO = 0V and RL = 2kΩ to ground.
Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 9)
95
Typ
(Note 8)
130
Max
(Note 9)
Units
BW
−3dB BW
AV = +1, VOUT = 200mVPP
AV = +2, −1, VOUT = 200mVPP
AV = +2, RL = 150Ω to V+/2,
Rf = 806Ω, VOUT = 200mVPP
AV = +1, −1dB, VOUT = 2VPP
f = 100kHz
MHz
46
BW0.1dB
0.1dB Gain Flatness
12
MHz
MHz
PBW
en
Full Power Bandwidth
24
17
48
Input-Referred Voltage Noise
nV/
f = 1kHz
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4
5V Electrical Characteristics (Continued)
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = −5V, VCM = VO = 0V and RL = 2kΩ to ground.
Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 9)
Typ
(Note 8)
0.90
Max
(Note 9)
Units
in
Input-Referred Current Noise
f = 100kHz
pA/
f = 1kHz
3.3
THD
DG
Total Harmonic Distortion
Differential Gain
f = 5MHz, VO = 2VPP, AV = +2
NTSC, AV = +2
RL =150Ω to V+/2
RL =1kΩ to V+/2
NTSC, AV = +2
RL =150Ω to V+/2
RL =1kΩ to V+/2
f = 5MHz, Receiver:
Rf = Rg = 510Ω, AV = +2
−62
dBc
%
0.15
0.01
0.04
0.01
47
DP
Differential Phase
deg
CT Rej.
TS
Cross-Talk Rejection
Settling Time
dB
ns
VO = 2VPP
,
0.1%, 8pF Load,
68
135
1
VS = 5V
SR
Slew Rate (Note 11)
Input Offset Voltage
AV = −1, VI = 2VPP
100
V/µs
mV
VOS
5
7
TC VOS
IB
Input Offset Average Drift
Input Bias Current
(Note 15)
(Note 10)
5
µV/˚C
µA
−2.60
−3.25
800
−1.60
IOS
Input Offset Current
20
3
nA
1000
RIN
Common Mode Input
Resistance
MΩ
CIN
Common Mode Input
Capacitance
pF
2
CMVR
Input Common-Mode Voltage
Range
CMRR ≥ 50dB
−5.2
−5.5
4.0
95
96
82
−5.1
V
3.8
3.6
CMRR
AVOL
Common Mode Rejection
Ratio
VCM Stepped from −5V to 3.5V
dB
74
Large Signal Voltage Gain
VO = −4.5V to 4.5V,
RL = 2kΩ
88
84
dB
VO = −4.0V to 4.0V,
RL = 150Ω
78
74
VO
Output Swing
High
RL = 2kΩ, VID = 200mV
RL = 150Ω, VID = 200mV
RL = 2kΩ, VID = −200mV
RL = 150Ω, VID = −200mV
Sourcing to Ground
VID = 200mV (Note 13)
Sinking to Ground
4.90
4.65
4.96
4.80
V
V
Output Swing
Low
−4.96
−4.80
−4.90
−4.65
ISC
Output Short Circuit Current
60
35
85
65
75
115
145
mA
VID = −200mV (Note 13)
IOUT
Output Current
VO = 0.5V from either supply
mA
dB
PSRR
Power Supply Rejection Ratio (V+, V−) = (4.5V, −4.5V) to (5.5V,
−5.5V)
78
90
IS
Supply Current (per channel)
No Load
4.50
2.70
mA
5.50
5
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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, 1.5kΩ in 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 T
, θ , and T . The maximum allowable power dissipation at any ambient temperature is
J(MAX)
JA
A
P
= (T - T )/ θ . All numbers apply for packages soldered directly onto a PC board.
J(MAX) A JA
D
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, 0Ω in series with 200pF.
Note 13: Short circuit test is a momentary test. See Note 14.
<
>
6V, allowable short circuit duration is 1.5ms.
Note 14: Output short circuit duration is infinite for V
6V at room temperature and below. For V
S
S
Note 15: Offset voltage average drift determined by dividing the change in V
at temperature extremes by the total temperature change.
OS
Connection Diagrams
SOIC-8 and MSOP-8
(LMH6643)
SOT23-5 (LMH6642)
SOIC-8 (LMH6642)
20089461
20089462
Top View
Top View
20089463
Top View
SOIC-14 and TSSOP-14
(LMH6644)
20089468
Top View
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6
Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless oth-
erwise specified.
Closed Loop Frequency Response for Various Supplies
Closed Loop Gain vs. Frequency for Various Gain
20089457
20089451
Closed Loop Frequency Response for Various
Temperature
Closed Loop Gain vs. Frequency for Various Gain
20089450
20089435
Closed Loop Frequency Response for Various
Temperature
Closed Loop Gain vs. Frequency for Various Supplies
20089448
20089434
7
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Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless
otherwise specified. (Continued)
Closed Loop Small Signal Frequency Response for
Large Signal Frequency Response
Various Supplies
20089446
20089447
Closed Loop Frequency Response for Various Supplies
0.1dB Gain Flatness for Various Supplies
20089444
20089445
<
<
VOUT (VPP) for THD 0.5%
VOUT (VPP) for THD 0.5%
20089409
20089408
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8
Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless
otherwise specified. (Continued)
<
VOUT (VPP) for THD 0.5%
Open Loop Gain/Phase for Various Temperature
20089432
20089410
Open Loop Gain/Phase for Various Temperature
HD2 (dBc) vs. Output Swing
20089433
20089414
HD3 (dBc) vs. Output Swing
HD2 vs. Output Swing
20089404
20089415
9
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Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 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
20089412
20089413
VOUT from V+ vs. ISOURCE
VOUT from V− vs. ISINK
20089418
20089419
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10
Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless
otherwise specified. (Continued)
VOUT from V+ vs. ISOURCE
VOUT from V− vs. ISINK
20089416
20089417
Swing vs. VS
Short Circuit Current (to VS/2) vs. VS
20089429
20089431
Output Sinking Saturation Voltage vs. IOUT
Output Sourcing Saturation Voltage vs. IOUT
20089420
20089401
11
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Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless
otherwise specified. (Continued)
Closed Loop Output Impedance vs. Frequency AV = +1
PSRR vs. Frequency
20089402
20089403
Crosstalk Rejection vs. Frequency
(Output to Output)
CMRR vs. Frequency
20089407
20089411
VOS vs. VOUT (Typical Unit)
VOS vs. VCM (Typical Unit)
20089427
20089430
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12
Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless
otherwise specified. (Continued)
VOS vs. VS (for 3 Representative Units)
VOS vs. VS (for 3 Representative Units)
20089422
20089423
VOS vs. VS (for 3 Representative Units)
IB vs. VS
20089425
20089424
IOS vs. VS
IS vs. VCM
20089428
20089426
13
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Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 2kΩ. Unless
otherwise specified. (Continued)
IS vs. VS
Small Signal Step Response
20089453
20089421
Large Signal Step Response
Large Signal Step Response
20089441
20089439
Small Signal Step Response
Small Signal Step Response
20089456
20089436
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14
Typical Performance Characteristics At TJ = 25˚C, V+ = +5, V− = −5V, RF = RL = 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
15
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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:
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 ft
(∼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, IOUT, etc.)
20089442
Significant power saving (∼40%) compared to competi-
tive devices on the market with similar performance.
FIGURE 1. Input and Output Shown with CMVR
Exceeded
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.
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.
Output overdrive recovery time is less than 100ns as can be
seen from Figure 2 plot:
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 ( AV = +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.
20089443
FIGURE 2. Overload Recovery Waveform
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.
www.national.com
16
Amp input capacitance and Q1 equivalent collector capaci-
tance together (CIN) will cause additional phase shift to the
signal fed back to the inverting node. Cf will function as a
zero in the feedback path counter-acting the effect of the CIN
and acting to stabilized the circuit. By proper selection of Cf
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.
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 1mApp from the
photodiode. Q1, in a common base configuration, isolates
the high capacitance of the photodiode (Cd) 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 VCC. 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.
(1)
where GBWP is the Gain Bandwidth Product of the Op Amp
Optimized as such, the I-V converter will have a theoretical
pole, fp, at:
(2)
With Op Amp input capacitance of 3pF and an estimate for
Q1 output capacitance of about 3pF as well, CIN = 6pF. From
the typical performance plots, LMH6642EP/6643EP family
GBWP is approximately 57MHz. Therefore, with Rf = 1k,
from Equation 1 and 2 above.
Cf = ∼4.1pF, and fp = 39MHz
No matter how low an Rf is selected, there is a need for Cf in
order to stabilize the circuit. The reason for this is that the Op
20089464
FIGURE 3. Single Supply Photodiode I-V Converter
17
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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:
Application Notes (Continued)
For this example, optimum Cf 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 fp. The overall supply current
from the +5V supply is around 5mA with no load.
Device
Package
Evaluation
Board PN
LMH6642MF
LMH6642MF
LMH6643MA
LMH6643MA
LMH6644MA
LMH6644MA
SOT23-5
8-Pin SOIC
8-Pin SOIC
8-Pin MSOP
14-Pin SOIC
14-Pin TSSOP
CLC730068
CLC730027
CLC730036
CLC730123
CLC730031
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 (1VPP, 20 ns/DIV)
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
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
19
www.national.com
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8-Pin MSOP
NS Package Number MUA08A
14-Pin SOIC
NS Package Number M14A
www.national.com
20
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
14-Pin TSSOP
NS Package Number MTC14
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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
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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
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2. A critical component is any component of a life
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