NSC LMH6645MF

LMH6645/46/47
2.7V, 650µA, 55MHz, Rail-to-Rail Input and Output
Amplifiers with Shutdown Option
General Description
Features
The LMH™6645 (single) and LMH6646 (dual), rail-to-rail
(VS = 2.7V, TA = 25˚C, RL = 1kΩ to V+/2, AV = +1. Typical
values unless specified).
n −3dB BW
55MHz
n Supply voltage range
2.5V to 12V
n Slew rate
22V/µs
n Supply current
650µA/channel
n Output short circuit current
42mA
± 20mA
n Linear output current
n Input common mode voltage
0.3V beyond rails
n Output voltage swing
20mV from rails
n Input voltage noise
17nV/
n Input current noise
0.75pA/
input and output voltage feedback amplifiers, offer high
speed (55MHz), and low voltage operation (2.7V) in addition
to micro-power shutdown capability (LMH6647, single).
Input common mode voltage range exceeds either supply by
0.3V, enhancing ease of use in multitude of applications
where previously only inferior devices could be used. Output
voltage range extends to within 20mV of either supply rails,
allowing wide dynamic range especially in low voltage applications. Even with low supply current of 650µA/amplifier,
output current capability is kept at a respectable ± 20mA for
driving heavier loads. Important device parameters such as
BW, Slew Rate and output current are kept relatively independent of the operating supply voltage by a combination of
process enhancements and design architecture.
In portable applications, the LMH6647 provides shutdown
capability while keeping the turn-off current to less than
50µA. Both turn-on and turn-off characteristics are well behaved with minimal output fluctuations during transitions.
This allows the part to be used in power saving mode, as
well as multiplexing applications. Miniature packages
(SOT23, MSOP-8, and SO-8) are further means to ease the
adoption of these low power high speed devices in applications where board area is at a premium.
Applications
n
n
n
n
n
Active filters
High speed portable devices
Multiplexing applications (LMH6647)
Current sense buffer
High speed transducer amp
Connection Diagrams
SOT23-5 (LMH6645)
SOT23-6 (LMH6647)
SOIC-8 (LMH6645)
20020260
20020259
Top View
Top View
20020261
Top View
LMH™ is a trademark of National Semiconductor Corporation.
© 2005 National Semiconductor Corporation
DS200202
www.national.com
LMH6645/46/47 2.7V, 650µA, 55MHz, Rail-to-Rail Input and Output Amplifiers with Shutdown
Option
June 2005
LMH6645/46/47
SOIC-8 and MSOP-8
(LMH6646)
SOIC-8 (LMH6647)
20020263
20020262
Top View
Top View
Ordering Information
Package
Part Number
Package Marking
Transport Media
NSC Drawing
5-Pin SOT-23
LMH6645MF
A68A
1k Units Tape and Reel
MF05A
LMH6645MFX
6-Pin SOT-23
LMH6647MF
3k Units Tape and Reel
A69A
1k Units Tape and Reel
LMH6647MFX
SOIC-8
LMH6645MA
LMH6645MA
LMH6645MAX
LMH6646MA
LMH6646MM
LMH6647MA
95 Units Rails
95 Units Rails
2.5k Units Tape and Reel
A70A
1k Units Tape and Reel
LMH6646MMX
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M08A
2.5k Units Tape and Reel
LMH6647MAX
MSOP-8
95 Units Rails
2.5k Units Tape and Reel
LMH6646MA
LMH6646MAX
LMH6647MA
MF06A
3k Units Tape and Reel
3.5k Units Tape and Reel
2
MUA08A
Soldering Information
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
ESD Tolerance
Human Body
Storage Temperature Range
−40˚C to +85˚C
Package Thermal Resistance (Note 4) (θJA)
(Note 3, 11)
12.6V
SOT23-5
V+ +0.8V, V− −0.8V
SOT23-6
265˚C/W
SOIC-8
190˚C/W
MSOP-8
235˚C/W
Supply Voltage (V+ - V−)
Voltage at Input/Output pins
2.5V to 12V
Temperature Range (Note 4)
± 2.5V
Output Short Circuit Duration
260˚C
Supply Voltage (V+ – V−)
200V (Note 9)
VIN Differential
235˚C
Wave Soldering (10 sec)
Operating Ratings (Note 1)
2KV (Note 2)
Machine Model
Infrared or Convection (20 sec)
−65˚C to +150˚C
Junction Temperature (Note 4)
+150˚C
265˚C/W
2.7V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 2.7V, V− = 0V, VCM = VO = V+/2, and Rf = 2kΩ, and RL
= 1kΩ to V+/2. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 6)
Typ
(Note 5)
40
55
BW
−3dB BW
AV = +1, VOUT = 200mVPP,
VCM = 0.7V
en
Input-Referred Voltage Noise
f = 100kHz
17
f = 1kHz
25
in
Input-Referred Current Noise
f = 100kHz
0.75
f = 1kHz
1.20
CT Rej.
Cross-Talk Rejection
(LMH6646 only)
f = 5MHz, Receiver:
Rf = Rg = 510Ω, AV = +2
SR
Slew Rate
AV = −1, VO = 2VPP
(Note 8, 13)
TON
Max
(Note 6)
Units
MHz
nV/
pA/
47
dB
22
V/µs
Turn-On Time
(LMH6647 only)
250
ns
TOFF
Turn-Off Time
(LMH6647 only)
560
ns
THSD
Shutdown Threshold
(LMH6647 only)
IS ≤ 50µA
1.95
ISD
Shutdown Pin Input Current
(LMH6647 only)
(Note 7)
−20
VOS
Input Offset Voltage
0V ≤ VCM ≤ 2.7V
TC VOS
Input Offset Average Drift
(Note 12)
IB
Input Bias Current
VCM = 2.5V (Note 7)
0.40
2
2.2
VCM = 0.5V (Note 7)
−0.68
−2
−2.2
1
500
15
−3
−4
±1
2.30
µA
3
4
±5
0V ≤ VCM ≤ 2.7V
V
mV
µV/˚C
µA
IOS
Input Offset Current
RIN
Common Mode Input
Resistance
3
MΩ
CIN
Common Mode Input
Capacitance
2
pF
CMVR
Input Common-Mode Voltage
Range
CMRR ≥ 50dB
−0.5
3.0
2.8
3
3.2
−0.3
−0.1
nA
V
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LMH6645/46/47
Absolute Maximum Ratings (Note 1)
LMH6645/46/47
2.7V Electrical Characteristics
(Continued)
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 2.7V, V− = 0V, VCM = VO = V+/2, and Rf = 2kΩ, and RL
= 1kΩ to V+/2. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 6)
Typ
(Note 5)
Common Mode Rejection
Ratio
VCM Stepped from 0V to 2.7V
46
77
VCM Stepped from 0V to 1.55V
58
76
AVOL
Large Signal Voltage Gain
VO = 0.35V to 2.35V
76
74
87
VO
Output Swing
High
RL = 1k to V+/2
2.55
2.66
CMRR
Output Swing
Low
ISC
IOUT
Output Short Circuit Current
Output Current
RL = 10k to V+/2
2.68
RL = 1k to V+/2
40
+
RL = 10k to V /2
20
Sourcing to V−
VID = 200mV (Note 10)
43
Sinking to V+
VID = −200mV (Note 10)
42
VOUT = 0.5V from rails
+
75
Max
(Note 6)
Units
dB
dB
V
150
mV
mA
± 20
mA
83
dB
PSRR
Power Supply Rejection Ratio
V = 2.7V to 3.7V or
V− = 0V to −1V
IS
Supply Current (per channel)
Normal Operation
650
1250
Shutdown Mode (LMH6647 only)
15
50
µA
5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2, and Rf = 2kΩ, and RL
= 1kΩ to V+/2. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 6)
Typ
(Note 5)
40
55
BW
−3dB BW
AV = +1, VOUT = 200mVPP
en
Input-Referred Voltage Noise
f = 100kHz
17
f = 1kHz
25
in
Input-Referred Current Noise
f = 100kHz
0.75
f = 1kHz
1.20
CT Rej.
Cross-Talk Rejection
(LMH6646 only)
f = 5MHz, Receiver:
Rf = Rg = 510Ω, AV = +2
SR
Slew Rate
AV = −1, VO = 2VPP
(Note 8, 13)
TON
Turn-On Time (LMH6647 only)
TOFF
Turn-Off Time (LMH6647 only)
THSD
Shutdown Threshold
(LMH6647 only)
IS ≤ 50µA
ISD
Shutdown Pin Input Current
(LMH6647 only)
(Note 7)
VOS
Input Offset Voltage
0V ≤ VCM ≤ 5V
TC VOS
Input Offset Average Drift
(Note 12)
IB
Input Bias Current
VCM = 4.8V (Note 7)
IOS
Input Offset Current
Common Mode Input
Resistance
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nV/
pA/
47
15
dB
V/µs
22
ns
500
4.25
ns
4.60
−20
−3
−4
±1
3
4
4
mV
µV/C
+0.36
+2
−2.2
−0.68
−2
−2.2
1
500
3
V
µA
±5
0V ≤ VCM ≤ 5V
Units
MHz
210
VCM = 0.5V (Note 7)
RIN
Max
(Note 6)
µA
nA
MΩ
(Continued)
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = 0V, VCM = VO = V+/2, and Rf = 2kΩ, and RL
= 1kΩ to V+/2. Boldface limits apply at the temperature extremes.
Symbol
Parameter
CIN
Common Mode Input
Capacitance
CMVR
Input Common-Mode Voltage
Range
Conditions
Min
(Note 6)
Typ
(Note 5)
2
CMRR ≥ 50dB
−0.5
5.3
5.1
5.5
Common Mode Rejection
Ratio
VCM Stepped from 0V to 5V
56
82
VCM Stepped from 0V to 3.8V
66
85
AVOL
Large Signal Voltage Gain
VO = 1.5V to 3.5V
76
74
85
VO
Output Swing
High
RL = 1k to V+/2
4.80
4.95
CMRR
Output Swing
Low
ISC
IOUT
Output Short Circuit Current
Output Current
Max
(Note 6)
RL = 10k to V+/2
4.98
RL = 1k to V+/2
50
RL = 10k to V+/2
20
Sourcing to V−
VID = 200mV (Note 10)
55
Sinking to V+
VID = −200mV (Note 10)
53
VOUT = 0.5V From rails
± 20
+
−
Units
pF
−0.3
−0.1
V
dB
dB
V
200
mV
mA
mA
PSRR
Power Supply Rejection Ratio
V = 5V to 6V or V = 0V to −1V
IS
Supply Current (per channel)
Normal Operation
700
1400
Shutdown Mode (LMH6647 only)
10
50
75
95
dB
µA
± 5V Electrical Characteristics
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = −5V, VCM = VO = 0V, Rf = 2kΩ, and RL =
1kΩ to GND. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Conditions
Min
(Note 6)
Typ
(Note 5)
40
55
BW
−3dB BW
AV = +1, VOUT = 200mVPP
en
Input-Referred Voltage Noise
f = 100kHz
17
f = 1kHz
25
in
Input-Referred Current Noise
f = 100kHz
0.75
f = 1kHz
1.20
CT Rej.
Cross-Talk Rejection
(LMH6646 only)
f = 5MHz, Receiver:
Rf = Rg = 510Ω, AV = +2
SR
Slew Rate
AV = −1, VO = 2VPP (Note 8)
TON
Turn-On Time (LMH6647 only)
TOFF
Turn-Off Time (LMH6647 only)
THSD
Shutdown Threshold
(LMH6647 only)
IS ≤ 50µA
ISD
Shutdown Pin Input Current
(LMH6647 only)
(Note 7)
VOS
Input Offset Voltage
−5V ≤ VCM ≤ 5V
TC VOS
Input Offset Average Drift
(Note 12)
15
Max
(Note 6)
MHz
nV/
pA/
47
dB
22
V/µs
200
ns
700
ns
4.25
4.60
−20
−3
−4
±1
±5
5
Units
V
µA
3
4
mV
µV/˚C
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LMH6645/46/47
5V Electrical Characteristics
LMH6645/46/47
± 5V Electrical Characteristics
(Continued)
Unless otherwise specified, all limits guaranteed for at TJ = 25˚C, V+ = 5V, V− = −5V, VCM = VO = 0V, Rf = 2kΩ, and RL =
1kΩ to GND. Boldface limits apply at the temperature extremes.
Symbol
Parameter
Input Bias Current
IB
Conditions
Min
(Note 6)
VCM = 4.8V (Note 7)
VCM = −4.5V (Note 7)
−5V ≤ VCM ≤ 5V
Typ
(Note 5)
Max
(Note 6)
+0.40
+2
+2.2
−0.65
−2
−2.2
3
500
Units
µA
IOS
Input Offset Current
RIN
Common Mode Input
Resistance
3
MΩ
CIN
Common Mode Input
Capacitance
2
pF
CMVR
Input Common-Mode Voltage
Range
CMRR ≥ 50dB
−5.5
5.3
5.1
5.5
Common Mode Rejection
Ratio
VCM Stepped from −5V to 5V
60
84
VCM Stepped from −5V to 3.5V
66
104
AVOL
Large Signal Voltage Gain
VO = −2V to 2V
76
74
85
VO
Output Swing
High
4.70
4.92
RL = 10kΩ
4.97
Output Swing
Low
RL = 1kΩ
−4.93
RL = 10kΩ
−4.98
Output Short Circuit Current
Sourcing to V−
VID = 200mV (Note 10)
66
Sinking to V+
VID = −200mV (Note 10)
61
CMRR
ISC
IOUT
Output Current
RL = 1kΩ
−
V
dB
dB
V
−4.70
V
mA
± 20
VOUT = 0.5V from rails
+
−5.3
−5.1
nA
mA
PSRR
Power Supply Rejection Ratio
V = 5V to 6V or V = −5V to −6V
IS
Supply Current (per channel)
Normal Operation
725
1600
Shutdown Mode (LMH6647 only)
10
50
76
95
dB
µA
Note 1: 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 2: Human body model, 1.5kΩ in series with 100pF.
Note 3: 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 4: The maximum power dissipation is a function of TJ(MAX), θJA, and TA. The maximum allowable power dissipation at any ambient temperature is
PD = (TJ(MAX) - TA)/ θJA . All numbers apply for packages soldered directly onto a PC board.
Note 5: Typical values represent the most likely parametric norm.
Note 6: All limits are guaranteed by testing or statistical analysis.
Note 7: Positive current corresponds to current flowing into the device.
Note 8: Slew rate is the average of the rising and falling slew rates.
Note 9: Machine Model, 0Ω in series with 200pF.
Note 10: Short circuit test is a momentary test. See Note 11.
Note 11: 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 12: Offset voltage average drift determined by dividing the change in VOS at temperature extremes into the total temperature change.
Note 13: Guaranteed based on characterization only.
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6
LMH6645/46/47
Typical Performance Characteristics
At TJ = 25˚C. Unless otherwise specified.
Closed Loop Frequency Response for Various
Temperature
Frequency Response for Various AV
20020248
20020249
Open Loop Gain/Phase vs. Frequency for Various
Temperature
THD vs. Output Swing
20020250
20020253
THD vs. Output Swing
Output Swing vs. Frequency
20020254
20020255
7
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LMH6645/46/47
Typical Performance Characteristics At TJ = 25˚C. Unless otherwise specified.
Settling Time vs. Step Size
(Continued)
Noise vs. Frequency
20020252
20020234
+
−
VOUT from V vs. ISOURCE
VOUT from V vs. ISINK
20020237
20020238
+
+
Output Swing from V vs. RL (tied to VS/2)
Output Swing from V vs. RL (tied to VS/2)
20020202
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20020206
8
Output Swing from V+ vs. RL (tied to VS/2)
(Continued)
Output Swing from V− vs. RL (tied to VS/2)
20020204
20020203
−
−
Output Swing from V vs. RL (tied to VS/2)
Output Swing from V vs. RL (tied to VS/2)
20020205
20020207
Cap Load Tolerance and Setting Time vs. Closed Loop
Gain
ZOUT vs. Frequency
20020201
20020216
9
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LMH6645/46/47
Typical Performance Characteristics At TJ = 25˚C. Unless otherwise specified.
LMH6645/46/47
Typical Performance Characteristics At TJ = 25˚C. Unless otherwise specified.
PSRR vs. Frequency
(Continued)
CMRR vs. Frequency
20020247
20020251
Crosstalk Rejection vs. Frequency (Output to Output)
(LMH6646)
VOS Distribution
20020225
20020257
VOSvs. VS (A Typical Unit)
VOSvs. VOUT (A Typical Unit)
20020228
20020218
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10
VOSvs. VOUT (A Typical Unit)
(Continued)
VOSvs. VCM (A Typical Unit)
20020229
20020231
VOSvs. VCM (A Typical Unit)
VOSvs. VCM (A Typical Unit)
20020230
20020232
IB vs. VCM
IB vs. VCM
20020226
20020219
11
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LMH6645/46/47
Typical Performance Characteristics At TJ = 25˚C. Unless otherwise specified.
LMH6645/46/47
Typical Performance Characteristics At TJ = 25˚C. Unless otherwise specified.
IB vs. VS
(Continued)
IS vs. VCM
20020227
20020223
IS (mA) (per channel)
IS vs. VSHUTDOWN (LMH6647)
20020224
20020221
IS vs. VSHUTDOWN (LMH6647)
IS vs. VSHUTDOWN (LMH6647)
20020220
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20020222
12
Shutdown Pin and Supply Current vs. Shutdown Voltage
(Continued)
Small Signal Step Response
20020243
20020208
Large Signal Step Response
Large Signal Step Response
20020244
20020245
Output Overload Recovery
20020246
13
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LMH6645/46/47
Typical Performance Characteristics At TJ = 25˚C. Unless otherwise specified.
LMH6645/46/47
This device family is designed to avoid output phase reversal. With input over-drive, the output is kept near the supply
rail (or as close to it as mandated by the closed loop gain
setting and the input voltage). Figure 1, below, shows the
input and output voltage when the input voltage significantly
exceeds the supply voltages:
Application Notes
CIRCUIT DESCRIPTION
The LMH6645/6646/6647 family is based on National Semiconductor’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
Collector bias current.
• Rail-to-Rail input which allows the input common mode
voltage to go beyond either rail by about 0.5V typically.
• A class A-B “turn-around” stage with improved noise,
offset, and reduced power dissipation compared to similar speed devices (patent pending).
• Common Emitter push-pull output stage capable of 20mA
output current (at 0.5V from the supply rails) while consuming only ∼700µA of total supply current per channel.
This architecture allows output to reach within milli-volts
of either supply rail at light loads.
• Consistent performance from any supply voltage (2.7V10V) with little variation with supply voltage for the most
important specifications (e.g. BW, SR, IOUT, etc.)
20020233
FIGURE 1. Input/Output Shown with Exceeded Input
CMVR
APPLICATION HINTS
The total input common mode voltage range, which extends
from below V− to beyond V+, is covered by both a PNP and
a NPN stage. The NPN stage is switched on whenever the
input is less than 1.2V from V+ and the PNP stage covers the
rest of the range. In terms of the input voltage, there is an
overlapping region where both stages are processing the
input signal. This region is about 0.5V from beginning to the
end. As far as the device application is concerned, this
transition is a transparent operation. However, keep in mind
that the input bias current value and direction will depend on
which input stage is operating (see typical performance
characteristics for plots). For low distortion applications, it is
best to keep the input common mode voltage from transversing this transition point. Low gain settling applications, which
generally encounter larger peak-to-peak input voltages,
could be configured as inverting stages to eliminate common
mode voltage fluctuations.
In terms of the output, when the output swing approaches
either supply rail, the output transistor will enter a Quasisaturated state. A subtle effect of this operational region is
that there is an increase in supply current in this state (up to
1mA). The onset of Quasi-saturation region is a function of
output loading (current) and varies from 100mV at no load to
about 1V when output is delivering 20mA, as measured from
supplies. Both input common mode voltage and output voltage level effect the supply current (see typical performance
characteristics for plot).
With 2.7V supplies and a common mode input voltage range
that extends beyond either supply rail, the LMH6645/6646/
6647 family is well suited to many low voltage/low power
applications. Even with 2.7V supplies, the −3dB BW (@ AV =
+1) is typically 55MHz with a tested limit of 45MHz. Production testing guarantees that process variations will not compromise speed.
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As can be seen, the output does not exhibit any phase
reversal as some op amps do. However, if the input voltage
range is exceeded by more than a diode drop beyond either
rail, the internal ESD protection diodes will start to conduct.
The current flow in these ESD diodes should be externally
limited.
LMH6647
MICRO-POWER SHUTDOWN
The LMH6647 can be shutdown to save power and reduce
its supply current to less than 50µA guaranteed, by applying
a voltage to the SD pin. The SD pin is “active high” and
needs to be tied to V− for normal operation. This input is low
current ( < 20µA, 4pF equivalent capacitance) and a resistor
to V− (≤20kΩ) will result in normal operation. Shutdown is
guaranteed when SD pin is 0.4V or less from V+ at any
operating supply voltage and temperature.
In the shutdown mode, essentially all internal device biasing
is turned off in order to minimize supply current flow and the
output goes into Hi-Z (high impedance) mode. Complete
device Turn-on and Turn-off times vary considerably relative
to the output loading conditions, output voltage, and input
impedance, but is generally limited to less than 1µs (see
tables for actual data).
14
LMH6645/46/47
Application Notes
Figure 4 shows the output waveform.
(Continued)
During shutdown, the input stage has an equivalent circuit as
shown below in Figure 2
20020236
20020256
FIGURE 4. Output Held Low by Active Pull-Down
Circuit
FIGURE 2. LMH6647 Equivalent Input in Shutdown
Mode
If bipolar transistor power dissipation is not tolerable, the
switch could be by a N-channel enhancement mode MOSFET.
As can be seen above, in shutdown, there may be current
flow through the internal diodes shown, caused by input
potential, if present. This current may flow through the external feedback resistor and result in an apparent output signal.
In most shutdown applications the presence of this output is
inconsequential. However, if the output is “forced” by another
device such as in a multiplexer, the other device will need to
conduct the current described in order to maintain the output
potential.
To keep the output at or near ground during shutdown when
there is no other device to hold the output low, a switch
(transistor) could be used to shunt the output to ground.
Figure 3 shows a circuit where a NPN bipolar is used to keep
the output near ground (∼80mV):
2.7V SINGLE SUPPLY RRIO 2:1 MUX
The schematic show in Figure 5 will function as a 2:1 MUX
operating on a single 2.7V power supply, by utilizing the
shutdown feature of the LMH6647:
20020264
FIGURE 3. Active Pull-Down Schematic
20020258
FIGURE 5. 2:1 MUX Operating off a 2.7V Single Supply
15
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LMH6645/46/47
Application Notes
ground will cause frequency response peaking and possible
circuit oscillations (see Application Note OA-15 for more
information).
Another important parameter in working with high speed/
high performance amplifiers, is the component values selection. Choosing large valued external resistors, 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. Either way, keeping
the resistor values lower, will diminish this interaction. On the
other hand, choosing very low value resistors could load
down nodes and will contribute to higher overall power dissipation.
National Semiconductor suggests the following evaluation
boards as a guide for high frequency layout and as an aid in
device testing and characterization:
(Continued)
Figure 6 shows the MUX output when selecting between a
1MHz sine and a 250KHz triangular waveform.
20020235
FIGURE 6. 2:1 MUX Output
As can be seen in Figure 6, the output is well behaved and
there are no spikes or glitches due to the switching. Switching times are approximately around 500ns based on the time
when the output is considered “valid”.
Package
Evaluation
Board PN
LMH6645MF
SOT23-5
CLC730068
LMH6645MA
8-Pin SOIC
CLC730027
LMH6646MA
8-Pin SOIC
CLC730036
LMH6646MM
8-Pin MSOP
CLC730123
LMH6647MA
8-Pin SOIC
CLC730027
LMH6647MF
SOT23-6
CLC730116
These free evaluation boards are shipped when a device
sample request is placed with National Semiconductor.
PRINTED CIRCUIT BOARD LAYOUT, COMPONENT
VALUES SELECTION, AND EVALUATION BOARDS
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
www.national.com
Device
LMH6647 Evaluation
For normal operation, tie the SD pin to V−.
16
LMH6645/46/47
Physical Dimensions
inches (millimeters) unless otherwise noted
5-Pin SOT23
NS Package Number MF05A
6-Pin SOT23
NS Package Number MF06A
17
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LMH6645/46/47
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
8-Pin SOIC
NS Package Number M08A
8Pin MSOP
NS Package Number MUA08A
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18
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.
For the most current product information visit us at www.national.com.
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LMH6645/46/47 2.7V, 650µA, 55MHz, Rail-to-Rail Input and Output Amplifiers with Shutdown
Option
Notes