LINER LT1638IN8 1.2mhz, 0.4v/us over-the-toptm micropower rail-to-rail input and output op amp Datasheet

LT1638/LT1639
1.2MHz, 0.4V/µs
Over-The-TopTM Micropower
Rail-to-Rail Input and Output
Op Amps
DESCRIPTION
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FEATURES
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Operates with Inputs Above V +
Rail-to-Rail Input and Output
Low Power: 230µA per Amplifier Max
Gain Bandwidth Product: 1.2MHz
Slew Rate: 0.4V/µs
High Output Current: 25mA Min
Specified on 3V, 5V and ±15V Supplies
Reverse Battery Protection to 18V
No Supply Sequencing Problems
High Voltage Gain: 1500V/mV
Single Supply Input Range: – 0.4V to 44V
High CMRR: 98dB
No Phase Reversal
The LT ®1638 is a low power dual rail-to-rail input and output
operational amplifier available in the standard 8-pin PDIP and
SO packages as well as the 8-lead MSOP package. The
LT1639 is a low power quad rail-to-rail input and output
operational amplifier offered on the standard 14-pin PDIP
and surface mount packages.
The LT1638/LT1639 op amps operate on all single and
split supplies with a total voltage of 2.5V to 44V drawing
only 170µA of quiescent current per amplifier. These
amplifiers are reverse battery protected and draw no
current for reverse supply up to 18V.
The input range of the LT1638/LT1639 includes both
supplies, and a unique feature of this device is its capability
to operate over the top with either or both of its inputs
above V +. The inputs handle 44V, both differential and
common mode, independent of supply voltage. The input
stage incorporates phase reversal protection to prevent
false outputs from occurring even when the inputs are 22V
below the negative supply. Protective resistors are
included in the input leads so that current does not
become excessive when the inputs are forced below the
negative supply. The LT1638/LT1639 can drive loads up to
25mA and still maintain rail-to-rail capability. The op amps
are unity-gain stable and drive all capacitive loads up to
1000pF when optional output compensation is used.
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APPLICATIONS
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Battery- or Solar-Powered Systems
Portable Instrumentation
Sensor Conditioning
Supply Current Sensing
Battery Monitoring
Micropower Active Filters
4mA to 20mA Transmitters
, LTC and LT are registered trademarks of Linear Technology Corporation.
Over-The-Top is a trademark of Linear Technology Corporation.
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TYPICAL APPLICATION
Output Voltage vs Input Voltage
Over-The-Top Comparator with 100mV Hysteresis Centered at 0mV
10k
1M
5V
VCC
V1
VCC
VCC
1M
+
+
A
1/2 LT1638
B
1/2 LT1638
–
1M
V0
–
0V
10k
1M
1638/39 TA01
V2
VCC = 5V, VCM = 0V TO 44V, tPD = 27µs
1638/39 TA02
1
LT1638/LT1639
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ABSOLUTE MAXIMUM RATINGS
(Note 1)
Total Supply Voltage (V + to V –) .............................. 44V
Input Differential Voltage ......................................... 44V
Input Current ...................................................... ±25mA
Output Short-Circuit Duration (Note 2) ......... Continuous
Operating Temperature Range ................ – 40°C to 85°C
Specified Temperature Range (Note 3) .. – 40°C to 85°C
Junction Temperature ........................................... 150°C
Storage Temperature Range ................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
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PACKAGE/ORDER INFORMATION
TOP VIEW
TOP VIEW
OUT A
–IN A
+IN A
V–
1
2
3
4
V+
OUT B
–IN B
+IN B
MS8 PACKAGE
8-LEAD PLASTIC MSOP
TJMAX = 150°C, θJA = 250°C/ W (MS8)
ORDER PART NUMBER
LT1638CMS8
MS8 PART MARKING
LTCY
8
1
OUT A
8
7
6
5
7
2
–IN A
TOP VIEW
V+
OUT A
1
OUT B
–IN A
2
+IN A
3
V+
4
A
6
3
+IN A
–IN B
B
V–
5
4
+IN B
+IN B
5
S8 PACKAGE
8-LEAD PLASTIC SO
–IN B
6
TJMAX = 150°C, θJA = 130°C/ W (N8)
TJMAX = 150°C, θJA = 190°C/ W (S8)
OUT B
7
N8 PACKAGE
8-LEAD PDIP
D
13 –IN D
12 +IN D
11 V –
10 +IN C
B
C
9
– IN C
8
OUT C
S PACKAGE
14-LEAD PLASTIC SO
TJMAX = 150°C, θJA = 110°C/ W (N)
TJMAX = 150°C, θJA = 150°C/ W (S)
LT1638CS8
LT1638IS8
ORDER PART NUMBER
S8 PART MARKING
1638
A
N PACKAGE
14-LEAD PDIP
ORDER PART NUMBER
LT1638CN8
LT1638IN8
14 OUT D
LT1639CN
LT1639IN
1638I
LT1639CS
LT1639IS
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = half supply, TA = 25°C, unless otherwise noted. (Note 3)
SYMBOL
VOS
IOS
PARAMETER
Input Offset Voltage
Input Offset Voltage Drift
(Note 7)
Input Offset Current
CONDITIONS
LT1638 N, S Packages
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
LT1639 N, S Packages
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
LT1638C MS8 Package
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
LT1638/LT1639 N, S Packages
LT1638CMS8
VCM = 44V (Note 4)
2
MIN
TYP
200
●
●
300
●
●
350
●
●
●
●
●
●
2
2.5
1
MAX
600
850
950
700
950
1050
900
1150
1250
6
7
6
2.5
UNITS
µV
µV
µV
µV
µV
µV
µV
µV
µV
µV/°C
µV/°C
nA
µA
LT1638/LT1639
ELECTRICAL CHARACTERISTICS
VS = 3V, 0V; VS = 5V, 0V; VCM = VOUT = half supply, TA = 25°C, unless otherwise noted. (Note 3)
SYMBOL
IB
PARAMETER
Input Bias Current
Input Noise Voltage
en
in
RIN
Input Noise Voltage Density
Input Noise Current Density
Input Resistance
CIN
Input Capacitance
Input Voltage Range
CONDITIONS
VCM = 44V (Note 4)
VS = 0V
0.1Hz to 10Hz
f = 1kHz
f = 1kHz
Differential
Common Mode, VCM = 0V to 44V
CMRR
Common Mode Rejection Ratio
VCM = 0V to VCC – 1V
VCM = 0V to 44V (Note 8)
AVOL
Large-Signal Voltage Gain
VS = 3V, VO = 500mV to 2.5V, RL = 10k
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
VS = 5V, VO = 500mV to 4.5V, RL = 10k
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
VS = 3V, No Load
VS = 3V, ISINK = 5mA
VS = 5V, No Load
VS = 5V, ISINK = 10mA
VS = 3V, No Load
VS = 3V, ISOURCE = 5mA
VS = 5V, No Load
VS = 5V, ISOURCE = 10mA
VS = 3V, Short to GND
VS = 3V, Short to VCC
VS = 5V, Short to GND
VS = 5V, Short to VCC
VS = 3V to 12.5V, VCM = VO = 1V
IS = – 100µA per Amplifier
VOL
VOH
Output Voltage Swing Low
Output Voltage Swing High
ISC
Short-Circuit Current (Note 2)
PSRR
Power Supply Rejection Ratio
Reverse Supply Voltage
IS
GBW
SR
Minimum Operating Supply Voltage
Supply Current per Amplifier
(Note 5)
Gain Bandwidth Product
(Note 4)
Slew Rate
(Note 6)
MIN
●
●
1
1.4
TYP
20
8
0.1
1
20
0.3
2.5
5.5
5
●
0
●
●
88
80
98
88
200
133
100
400
250
200
1500
●
●
●
●
●
●
●
●
●
●
●
●
●
●
2.94
2.25
4.94
3.8
10
15
15
15
90
18
●
MAX
50
30
44
3
250
3
500
2.98
2.40
4.98
4.0
15
25
20
25
100
27
8
450
8
700
2.4
170
2.7
230
275
●
650
550
500
1075
●
●
AV = – 1, RL = ∞
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
0.210
0.185
0.170
0.38
●
●
nV/√Hz
pA/√Hz
MΩ
MΩ
pF
V
dB
dB
1500
f = 1kHz
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
UNITS
nA
µA
nA
µVP-P
V/mV
V/mV
V/mV
V/mV
V/mV
V/mV
mV
mV
mV
mV
V
V
V
V
mA
mA
mA
mA
dB
V
V
µA
µA
kHz
kHz
kHz
V/µs
V/µs
V/µs
3
LT1638/LT1639
ELECTRICAL CHARACTERISTICS
SYMBOL
VOS
IOS
IB
PARAMETER
Input Offset Voltage
Input Offset Voltage Drift
(Note 7)
Input Offset Current
Input Bias Current
Input Noise Voltage
en
in
RIN
Input Noise Voltage Density
Input Noise Current Density
Input Resistance
CIN
Input Capacitance
Input Voltage Range
CMRR
AVOL
Common Mode Rejection Ratio
Large-Signal Voltage Gain
VS = ±15V, VCM = 0V, VOUT = 0V, TA = 25°C, unless otherwise noted. (Note 3)
CONDITIONS
LT1638 N, S Packages
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
LT1639 N, S Packages
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
LT1638C MS8 Package
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
LT1638/LT1639 N, S Packages
LT1638CMS8
MIN
TYP
250
●
●
350
●
●
400
●
●
2
2.5
1
20
1
●
●
●
●
0.1Hz to 10Hz
f = 1kHz
f = 1kHz
Differential
Common Mode, VCM = – 15V to 14V
1
MAX
800
1000
1100
900
1100
1200
1050
1250
1350
6
7
6
50
20
0.3
2.5
500
4.5
●
– 15
VCM = –15V to 29V
VO = ±14V, RL = 10k
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
●
88
500
●
●
80
200
125
100
29
UNITS
µV
µV
µV
µV
µV
µV
µV
µV
µV
µV/°C
µV/°C
nA
nA
µVP-P
nV/√Hz
pA/√Hz
MΩ
MΩ
pF
V
dB
V/mV
V/mV
V/mV
VOL
Output Voltage Swing
No Load
IOUT = ±10mA
●
●
14.9
13.7
14.95
14.0
ISC
Short-Circuit Current (Note 2)
Short to GND
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
25
20
15
40
●
●
mA
mA
mA
VS = ±1.5V to ±22V
●
90
100
dB
PSRR
Power Supply Rejection Ratio
IS
Supply Current per Amplifier
205
●
GBW
SR
Gain Bandwidth Product
Slew Rate
280
350
µA
µA
f = 1kHz
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
750
650
600
1200
●
●
kHz
kHz
kHz
AV = – 1, RL = ∞, VO = ±10V,
0°C ≤ TA ≤ 70°C
– 40°C ≤ TA ≤ 85°C
0.225
0.2
0.18
0.4
●
●
V/µs
V/µs
V/µs
The ● denotes specifications which apply over the full specified
temperature range.
Note 1: Absolute Maximum Ratings are those values beyond which the
life of a device may be impaired.
Note 2: A heat sink may be required to keep the junction temperature
below absolute maximum. This depends on the power supply voltage
and how many amplifiers are shorted.
Note 3: The LT1638C/LT1639C are guaranteed to meet 0°C to 70°C
specifications and are designed, characterized and expected to meet
the extended temperature limits, but are not tested at – 40°C and 85°C.
The LT1638I/LT1639I are guaranteed to meet the extended
temperature limits.
4
V
V
Note 4: VS = 5V limits are guaranteed by correlation to VS = 3V and
VS = ±15V tests.
Note 5: VS = 3V limits are guaranteed by correlation to VS = 5V and
VS = ±15V tests.
Note 6: Guaranteed by correlation to slew rate at VS = ±15V and GBW
at VS = 3V and VS = ±15V tests.
Note 7: This parameter is not 100% tested.
Note 8: The spec implies a typical offset voltage at VCM = 44 of 2mV and
a maximum offset voltage at VCM = 44 of 5mV.
LT1638/LT1639
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TYPICAL PERFORMANCE CHARACTERISTICS
Supply Current vs Supply Voltage
260
TA = 125°C
240
220
TA = 25°C
200
180
TA = –55°C
160
140
120
400
10000
300
8000
200
100
0
0
5
10
15 20 25 30 35
SUPPLY VOLTAGE (V)
40
TA = 25°C
–100
TA = 125°C
TA = –55°C
–200
–300
– 400
100
INPUT BIAS CURRENT (nA)
CHANGE IN INPUT OFFSET VOLTAGE (µV)
SUPPLY CURRENT PER AMPLIFIER (µA)
300
280
Input Bias Current vs
Common Mode Voltage
Minimum Supply Voltage
45
0
1
3
4
2
TOTAL SUPPLY VOLTAGE (V)
TA = –55°C
0.01
0.1
1
SOURCING LOAD CURRENT (mA)
10
TA = 125°C
TA = 25°C
0.01
TA = –55°C
0.001
0.001
7
8
10
OUTPUT LOW
10
9
10
1638/39 G07
0 10 20 30 40 50 60 70 80 90 100
INPUT OVERDRIVE (mV)
1638/39 G06
1638/39 G05
Input Noise Current Density
vs Frequency
4.5
INPUT NOISE CURRENT DENSITY (pA/√Hz)
INPUT NOISE VOLTAGE DENSITY (nV/√Hz)
4 5 6
TIME (SEC)
OUTPUT HIGH
1
0.01
0.1
1
SINKING LOAD CURRENT (mA)
70
3
44
VS = ±2.5V
NO LOAD
Noise Voltage Density vs
Frequency
VS = ±2.5
4.4
5.2
5.6
4.8
COMMON MODE VOLTAGE (V)
100
0.1
0.1Hz to 10Hz Noise Voltage
2
TA = 25°C
Output Saturation Voltage vs
Input Overdrive
VS = ±2.5V
VOD = 30mV
1638/39 G04
1
TA = 125°C
0
1638/39 G03
OUTPUT SATURATION VOLTAGE (mV)
OUTPUT SATURATION VOLTAGE (V)
TA = 25°C
0
20
–40
4.0
5
1
NOISE VOLTAGE (400nV/DIV)
OUTPUT SATURATION VOLTAGE (V)
1
0.01
0.001
40
Output Saturation Voltage vs
Load Current (Output Low)
TA = 125°C
TA = –55°C
60
1638/39 G02
Output Saturation Voltage vs
Load Current (Output High)
0.1
6000
–20
1638/39 G01
VS = ±2.5V
VOD = 30mV
VS = 5V, 0V
60
50
40
30
20
10
0
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1
10
100
FREQUENCY (Hz)
1k
1638/39 G09
1
10
100
FREQUENCY (Hz)
1k
1638/39 G08
5
LT1638/LT1639
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TYPICAL PERFORMANCE CHARACTERISTICS
Gain and Phase Shift vs
Frequency
Gain Bandwith Product vs
Temperature
100
80
PHASE
50
70
40
60
50
GAIN
20
40
10
30
0
20
10
–10
0
1000
–20
10
100
FREQUENCY (kHz)
1
1400
0.55
1300
VS = ±15V
1200
1100
1000
VS = ±2.5V
900
800
–50 –25
50
0
75
25
TEMPERATURE (°C)
1638/39 G12
GAIN BANDWIDTH
30
20
1100
5
10 15 20 25 30 35 40
TOTAL SUPPLY VOLTAGE (V)
GAIN BANDWIDTH PRODUCT (kHz)
40
1300
0
VS = ± 2.5V
AV = –1
RF = RG = 100k
f = 1kHz
1400
1300
50
25
0
75
TEMPERATURE (°C)
1100
20
GAIN BANDWIDTH
PRODUCT
1000
90
50
30
10
900
0
800
–10
100
1
10
LOAD RESISTANCE (kΩ)
VS = ±15V
125
70
60
POSITIVE SUPPLY
50
40
30
NEGATIVE SUPPLY
20
10
0
–10
1
10
100
FREQUENCY (kHz)
1000
1638/39 G16
Output Impedance vs Frequency
Channel Separation vs Frequency
130
100
VS = ±2.5V
80
1638/39 G17
10k
VS = ±15V
VS = ± 2.5V
90
80
70
60
50
40
OUTPUT IMPEDANCE (Ω)
120
CHANNEL SEPARATION (dB)
COMMON MODE REJECTION RATIO (dB)
FALLING, VS = ±15V
PSRR vs Frequency
1200
10
45
100
110
100
90
80
1k
100
AV = 10
AV = 100
10
AV = 1
1
70
30
20
1
10
100
FREQUENCY (kHz)
1000
1638/39 G18
6
FALLING, VS = ±2.5V
0.35
1638/39 G14
60
PHASE MARGIN
CMRR vs Frequency
110
0.40
0.25
–50 –25
125
40
1638/39 G15
120
100
PHASE MARGIN (DEG)
PHASE MARGIN
PHASE MARGIN (DEG)
GAIN BANDWIDTH PRODUCT (kHz)
1500
50
1400
1000
RISING, VS = ±2.5V
0.45
Gain Bandwidth Product and
Phase Margin vs Load Resistance
60
1200
0.50
1638/39 G13
Gain Bandwidth Product and
Phase Margin vs Supply Voltage
1500
RISING, VS = ±15V
0.30
POWER SUPPLY REJECTION RATIO (dB)
30
PHASE SHIFT (DEG)
GAIN (dB)
f = 1kHz
90
60
0.60
SLEW RATE (V/µs)
VS = ±2.5V
70
Slew Rate vs Temperature
1500
GAIN BANDWIDTH PRODUCT (kHz)
80
60
0.1
1
10
FREQUENCY (kHz)
100
1638/39 G19
0.1
0.1
1
10
100
FREQUENCY (kHz)
1000
1638/39 G20
LT1638/LT1639
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TYPICAL PERFORMANCE CHARACTERISTICS
Settling Time to 0.1% vs
Output Step
100
VS = ±15V
8
OVERSHOOT (%)
2
0
–2
–4
AV = –1
–6
60
AV = 5
AV = 1
40
30
AV = 10
5
20
15
10
25
SETTLING TIME (µs)
15
10
VS = ± 2.5V
0
0.1
0
–10
0
20
5
10
10
35
30
100
1000
CAPACITIVE LOAD (pF)
10000
DISTORTION ≤ 1%
RL = 20k
25
20
AV = 1
–8
70
50
VS = ±15V
30
1
10
FREQUENCY (kHz)
100
1638/39 G21
1638/39 G22
1638/39 G23
Total Harmonic Distortion + Noise
vs Frequency
Total Harmonic Distortion + Noise
vs Load Resistance
Total Harmonic Distortion + Noise
vs Output Voltage
10
10
10
VS = 3V TOTAL
AV = 1
VIN = 2VP-P AT 1kHz
VS = 3V, 0V
VOUT = 2VP-P
VCM = 1.2V
RL = 20k
0.1
0.01
VS = ±1.5V
VIN = ±1V
0.1
VS = 3V, 0V
VIN = 0.5V TO 2.5V
0.01
AV = –1
0.1
1
10
FREQUENCY (Hz)
100
0.001
0.1
CHANGE IN INPUT OFFSET VOLTAGE (50µV/DIV)
Open-Loop Gain
0.001
1
10
LOAD RESISTANCE TO GROUND (kΩ)
1638/39 G24
0.1
0.01
VS = 3V, 0V
VIN = 0.2V TO 2.2V
AV = 1
0.001
0.01
RL = 10k, f = 1kHz
VCM = HALF SUPPLY
A V = –1, VS = ±1.5V
AV = –1, VS = 3V, 0V
AV = 1, VS = ±1.5V
AV = 1, VS = 3V, 0V
1
1
THD + NOISE (%)
1
THD + NOISE (%)
OUTPUT STEP (V)
80
AV = –1
4
35
VS = 5V, 0V
VCM = 2.5V
ISOURCE = 150µA
90
AV = 1
6
THD + NOISE (%)
Undistorted Output Swing
vs Frequency
OUTPUT SWING (VP-P)
10
Capacitive Load Handling,
Overshoot vs Capacitive Load
100
0
2
1
OUTPUT VOLTAGE (VP-P)
1638/39 G26
1638/39 G25
Large-Signal Response
3
Small-Signal Response
VS = ±15V
RL = 2k
RL = 10k
RL = 50k
VS = ±15V
AV = 1
–20V
–10V
10V
0V
OUTPUT VOLTAGE (5V/DIV)
1638/39 G28
VS = ±15V
AV = 1
CL = 15pF
1638/39 G29
20V
1638/39 G27
7
LT1638/LT1639
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APPLICATIONS INFORMATION
Supply Voltage
The positive supply pin of the LT1638/LT1639 should be
bypassed with a small capacitor (typically 0.1µF) within an
inch of the pin. When driving heavy loads an additional
4.7µF electrolytic capacitor should be used. When using
split supplies, the same is true for the negative supply pin.
The LT1638/LT1639 are protected against reverse battery
voltages up to 18V. In the event a reverse battery condition
occurs, the supply current is less than 1nA.
The LT1638/LT1639 can be shut down by removing V +. In
this condition the input bias current is less than 0.1nA,
even if the inputs are 44V above the negative supply.
At temperatures greater than 70°C, when operating the
LT1638/LT1639 on total supplies of 10V or more, the
supply must not be brought up faster than 1V/µs. Increasing the bypass capacitor and/or adding a small resistor in
series with the supply will limit the rise time.
Inputs
The LT1638/LT1639 have two input stages, NPN and PNP
(see the Simplified Schematic), resulting in three distinct
operating regions as shown in the Input Bias Current vs
Common Mode typical performance curve.
For input voltages about 0.8V or more below V +, the PNP
input stage is active and the input bias current is typically
– 20nA. When the input common mode voltage is within
0.5V of the positive rail, the NPN stage is operating and the
input bias current is typically 40nA. Increases in temperature will cause the voltage at which operation switches
from the PNP input stage to the NPN input stage to move
towards V +. The input offset voltage of the NPN stage is
untrimmed and is typically 600µV.
A Schottky diode in the collector of each NPN transistor
allow the LT1638/LT1639 to operate over the top, with
either or both of its inputs above V +. At about 0.3V above
V + the NPN input transistor is fully saturated and the input
bias current is typically 8µA at room temperature. The
input offset voltage is typically 2mV when operating above
V +. The LT1638/LT1639 will operate with its inputs 44V
above V – regardless of V +.
8
The inputs are protected against excursions as much as
22V below V – by an internal 1k resistor in series with each
input and a diode from the input to the negative supply.
The input stage of the LT1638/LT1639 incorporates phase
reversal protection to prevent the output from phase
reversing for inputs up to 22V below V –. There are no
clamping diodes between the inputs and the maximum
differential input voltage is 44V.
Output
The output of the LT1638/LT1639 can swing within 20mV
of the positive rail with no load, and within 3mV of the
negative rail with no load. When monitoring voltages
within 20mV of the positive rail or within 3mV of the
negative rail, gain should be taken to keep the output from
clipping. The LT1638/LT1639 are capable of sinking and
sourcing over 40mA on ±15V supplies; sourcing current
capability is reduced to 20mA at 5V total supplies as noted
in the electrical characteristics.
The LT1638/LT1639 are internally compensated to drive
at least 200pF of capacitance under any output loading
conditions. A 0.22µF capacitor in series with a 150Ω
resistor between the output and ground will compensate
these amplifiers for larger capacitive loads, up to 1000pF,
at all output currents.
Distortion
There are two main contributors of distortion in op amps:
output crossover distortion as the output transitions from
sourcing to sinking current and distortion caused by nonlinear common mode rejection. If the op amp is operating
inverting there is no common mode induced distortion. If
the op amp is operating in the PNP input stage (input is not
within 0.8V of V +), the CMRR is very good, typically 98dB.
When the LT1638 switches between input stages there is
significant nonlinearity in the CMRR. Lower load resistance increases the output crossover distortion, but has
no effect on the input stage transition distortion. For lowest distortion the LT1638/LT1639 should be operated single
supply, with the output always sourcing current and with
the input voltage swing between ground and (V + – 0.8V).
See the Typical Performance Characteristics curves.
LT1638/LT1639
U
U
W
U
APPLICATIONS INFORMATION
Gain
The open-loop gain is almost independent of load when
the output is sourcing current. This optimizes perfor-
mance in single supply applications where the load is
returned to ground. The typical performance curve of
Open-Loop Gain for various loads shows the details.
U
TYPICAL APPLICATIONS
With 1.2MHz bandwidth, Over-The-Top capability, reverse-battery protection and rail-to-rail input and output
features, the LT1638/LT1639 are ideal candidates for
general purpose applications.
VCC
R5
100k
+
1/4 LT1639
The lowpass slope limiting filter in Figure 1 limits the
maximum dV/dT (not frequency) that it passes. When the
input signal differs from the output by one forward diode
drop, D1 or D2 will turn on. With a diode on, the voltage
across R2 will be constant and a fixed current, VDIODE/R2,
will flow through capacitor C1, charging it linearly instead
of exponentially. The maximum slope that the circuit will
pass is equal to VDIODE divided by (R2)(C1). No matter
how fast the input changes the output will never change
any faster than the dV/dT set by the diodes and (R2)(C).
D1 R3
100k
–
R1
1k
R4
100k
D3
VD
d
=
V
dt OUT(MAX) (R2)(C1)
FOR R1 = 10k, R2 = 100k, C1 = 1000pF
d
V
= 0.006V/µs
dt OUT(MAX)
C1
LT1634-1.2V
D4
–
1/4 LT1639
FOR R2 = 50k, C1 = 500pF,
MAXIMUM SLOPE = 0.048V/µs
1.2V
d
=
V
dt OUT (R2)(C1)
+
VIN
+
C1
D2
R2
VOUT
1/4 LT1639
R2
VIN
D1
R1
LT1634-1.2V
–
D2
1/2 LT1638
+
R6
100k
1638/39 F02
VEE
VOUT
–
Response of Slope Limiting Filter
1638/39 F01
Figure 1. Lowpass Slope Limiting Filter
VOUT
A modification of this application is shown in Figure 2
using references instead of diodes to set the maximum
slope. By using references, the slope is independent of
temperature. A scope photo shows a 1VP-P, 2kHz input
signal with a 2V pulse added to the sine wave; the circuit
passes the 2kHz signal but limits the slope of the pulse.
The application in Figure 3 utilizes the Over-The-Top
capabilities of the LT1638. The 0.2Ω resistor senses the
load current while the op amp and NPN transistor form a
closed loop making the collector current of Q1
VIN
1638/39 TA02
Figure 2. Lowpass Slope Limiting Filter with 0TC
9
LT1638/LT1639
U
TYPICAL APPLICATIONS
proportional to the load current. As a convenient monitor,
the 2k load resistor converts the current into a voltage. The
positive supply rail, V +, is not limited to the 5V supply of
the op amp and could be as high as 44V.
The Figure 4 application uses the LT1638 in conjunction
with the LT1634 micropower shunt reference. The supply
current of the op amp also biases the reference. The drop
across resistor R1 is fixed at 1.2V generating an output
current equal to 1.2V/R1.
V+
200Ω
VCC
LT1634-1.2
5V
0.2Ω
R1
+
Q1
2N3904
1/2 LT1638
200Ω
LOAD
VCC
–
+
0V TO 4.3V
ILOAD
IOUT = 1.2V
R1
1/2 LT1638
2k
–
IOUT
1638/39 F03
VOUT = (2Ω)(ILOAD)
1638/39 F04
Figure 3. Positive Supply Rail Current Sense
Figure 4. Current Source
W
W
SI PLIFIED SCHE ATIC
V+
Q2
Q1
D1
R1
6k
Q3
Q22
D3
D2
R2
1k
Q4
Q19
– IN
Q17
Q7
R3
1k
+
Q8
Q11
OUT
Q16
+IN
10µA
Q6
Q18
Q15
Q9
Q5
Q20
Q12
D4
Q10
Q13
Q14
R4
8k
D5
Q21
R5
8k
V–
ONE AMPLIFIER
1638/39 SS
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.040 ± 0.006
(1.02 ± 0.15)
0.007
(0.18)
0.034 ± 0.004
(0.86 ± 0.102)
8
7 6
5
0° – 6° TYP
0.021 ± 0.006
(0.53 ± 0.015)
SEATING
PLANE 0.012
(0.30)
0.0256
REF
(0.65)
TYP
0.006 ± 0.004
(0.15 ± 0.102)
* DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,
PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
10
0.118 ± 0.004*
(3.00 ± 0.102)
0.118 ± 0.004**
(3.00 ± 0.102)
0.192 ± 0.004
(4.88 ± 0.10)
MSOP (MS8) 1197
1
2 3
4
LT1638/LT1639
U
PACKAGE DESCRIPTION Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.300 – 0.325
(7.620 – 8.255)
0.045 – 0.065
(1.143 – 1.651)
0.130 ± 0.005
(3.302 ± 0.127)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
(
0.400*
(10.160)
MAX
+0.035
0.325 –0.015
+0.889
8.255
–0.381
)
8
7
6
5
1
2
3
4
0.255 ± 0.015*
(6.477 ± 0.381)
0.125
(3.175) 0.020
MIN (0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
N8 1197
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.053 – 0.069
(1.346 – 1.752)
0.008 – 0.010
(0.203 – 0.254)
0.189 – 0.197*
(4.801 – 5.004)
7
8
0.004 – 0.010
(0.101 – 0.254)
5
6
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
0.050
(1.270)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
SO8 0996
1
3
2
4
N Package
14-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.130 ± 0.005
(3.302 ± 0.127)
0.300 – 0.325
(7.620 – 8.255)
0.045 – 0.065
(1.143 – 1.651)
0.020
(0.508)
MIN
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
+0.035
0.325 –0.015
(
+0.889
8.255
–0.381
)
0.770*
(19.558)
MAX
0.125
(3.175)
MIN
0.005
(0.125)
MIN
0.100 ± 0.010
(2.540 ± 0.254)
14
13
12
11
10
9
8
1
2
3
4
5
6
7
0.255 ± 0.015*
(6.477 ± 0.381)
0.018 ± 0.003
(0.457 ± 0.076)
N14 1197
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S Package
14-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0.337 – 0.344*
(8.560 – 8.738)
14
13
12
11
10
9
8
0° – 8° TYP
0.050
(1.270)
TYP
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.016 – 0.050
0.406 – 1.270
0.014 – 0.019
(0.355 – 0.483)
0.228 – 0.244
(5.791 – 6.197)
0.150 – 0.157**
(3.810 – 3.988)
S14 0695
1
2
3
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
4
5
6
7
11
LT1638/LT1639
U
TYPICAL APPLICATION
The battery monitor in Figure 5 also demonstrates the
LT1638’s ability to operate with its inputs above the
positive rail. In this application, a conventional amplifier
would be limited to a battery voltage between 5V and
ground, but the LT1638 can handle battery voltages as
high as 44V. When the battery is charging, Amp B senses
the voltage drop across RS. The output of Amp B causes
Q2 to drain sufficient current through RB to balance the
input of Amp B. Likewise, Amp A and Q1 form a closed
RS, 0.2Ω
CHARGER
VOLTAGE
RA, 2k
RA', 2k
IBATT
loop when the battery is discharging. The current through
Q1 or Q2 is proportional to the current in R S and this
current flows into RG and is converted into a voltage. Amp
D buffers and amplifies the voltage across RG. Amp C
compares the output of Amp A and Amp B to determine
the polarity of current through RS. The scale factor for
VOUT with S1 open is 1V/A. With S1 closed the scale factor
is 1V/100mA and currents as low as 500µA can be
measured.
Q1
2N3904
+
A
1/4 LT1639
+
C
1/4 LT1639
–
LOGIC
–
RB, 2k
RB', 2k
LOAD
+
+
Q2
2N3904
LOGIC HIGH (5V) = CHARGING
LOGIC LOW (0V) = DISCHARGING
B
1/4 LT1639
+
–
RG
10k
VBATT = 12V
D
1/4 LT1639
VOUT
–
S1
90.9k
10k
1638/39 F05
IBATT =
VOUT
V
= OUT AMPS
(RS)(RG /RA)(GAIN) GAIN
S1 = OPEN, GAIN = 1
S1 = CLOSED, GAIN = 10
RA = RB
VS = 5V, 0V
Figure 5. Battery Monitor
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1078/LT1079
LT2078/LT2079
Dual/Quad 55µA Max, Single Supply, Precision Op Amps
Input/Output Common Mode Includes Ground, 70µV VOS(MAX)
and 2.5µV/°C Drift (Max), 200kHz GBW, 0.07V/µs Slew Rate
LT1178/LT1179
LT2178/LT2179
Dual/Quad 17µA Max, Single Supply, Precison Op Amps
Input/Output Common Mode Includes Ground, 70µV VOS(MAX)
and 4µV/°C Drift (Max), 85kHz GBW, 0.04V/µs Slew Rate
LT1366/LT1367
Dual/Quad Precision, Rail-to-Rail Input and Output Op Amps
475µV VOS(MAX), 500V/mV AVOL(MIN), 400kHz GBW
LT1490/LT1491
Dual/Quad Over-The-Top Micropower, Rail-to-Rail Input and
Output Op Amps
Single Supply Input Range: – 0.4V to 44V, Micropower 50µA
per Amplifier, Rail-to-Rail Input and Output, 200kHz GBW
LT1636
Single Over-The-Top Micropower Rail-to-Rail Input and Output
Op Amp
55µA Supply Current, VCM Extends 44V above VEE,
Independent of VCC; MSOP Package, Shutdown Function
12
Linear Technology Corporation
16389f LT/TP 1098 4K • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com
 LINEAR TECHNOLOGY CORPORATION 1998
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