Datasheet LT1637 Datasheet (Linear Technology)

Page 1
FEATURES
LT1637
1.1MHz, 0.4V/µs
Over-The-Top Micropower, Rail-To-Rail
Input and Output Op Amp
U
DESCRIPTIO
Operates with Inputs Above V
Rail-to-Rail Input and Output
Micropower: 250µA Supply Current Max
Gain-Bandwidth Product: 1.1MHz
Slew Rate: 0.4V/µs
Low Input Offset Voltage: 350µV Max
Single Supply Input Range: –0.4V to 44V
High Output Current: 25mA Min
Specified on 3V, 5V and ±15V Supplies
Output Shutdown
Output Drives 4700pF with Output Compensation
Reverse Battery Protection to 25V
High Voltage Gain: 800V/mV
High CMRR: 110dB
+
U
APPLICATIO S
Battery or Solar Powered Systems: Portable Instrumentation Sensor Conditioning
Supply Current Sensing
Battery Monitoring
MUX Amplifiers
4mA to 25mA Transmitters
The LT®1637 is a rugged op amp that operates on all single and split supplies with a total voltage of 2.7V to 44V. The LT1637 has a gain-bandwidth product of 1.1MHz while
drawing less than 250µA of quiescent current. The LT1637
reducing the quiescent current to only 3µA. The LT1637 is
reverse supply protected: it draws virtually no current for reverse supply up to 25V. The input range of the LT1637 includes both supplies and the output swings to both supplies. Unlike most micropower op amps, the LT1637 can drive heavy loads; its rail-to-rail output drives 25mA. The LT1637 is unity-gain stable into all capacitive loads up
to 4700pF when optional 0.22µF and 150 compensation
is used.
The LT1637 has a unique input stage that operates and remains high impedance when above the positive supply. The inputs take 44V both differential and common mode, even when operating on a 3V supply. Built-in resistors protect the inputs for faults below the negative supply up to 22V. There is no phase reversal of the output for inputs 5V below VEE or 44V above VEE, independent of VCC.
The LT1637 op amp is available in the 8-pin MSOP, PDIP and SO packages.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Over-The-Top is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
Switchable Precision Current Source Current Source Timing
+
R*
SHDN
LT1004-1.24.7µF
2k
+
LT1637
*OPTIONAL FOR LOW OUTPUT CURRENTS, R* = R
U
Over-The-TopTM Current Source with Shutdown
I
OUT
R
TP0610
4V TO 44V
1.2
=
I
OUT
R
e.g., 10mA = 120
1637 TA01
V
SHDN
I
OUT
6V
4V
2V
0V
10mA
5mA
0mA
100µs/DIV 1637 TA01b
1
Page 2
LT1637
1
2
3
4
8
7
6
5
TOP VIEW
NULL
V
+
OUT
SHDN
NULL
IN
+
IN
V
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE 8-LEAD PDIP
1 2 3 4
NULL
IN
+
IN
V
8 7 6 5
NULL V
+
OUT SHDN
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
WW
W
U
ABSOLUTE AXI U RATI GS
(Note 1)
Total Supply Voltage (V+ to V–) .............................. 44V
Input Differential Voltage ......................................... 44V
Input Current ...................................................... ±25mA
Shutdown Pin Voltage Above V
.....................................
32V
Shutdown Pin Current ........................................ ±10mA
Output Short-Circuit Duration (Note 2) ......... Continuous
UUW
PACKAGE/ORDER I FOR ATIO
ORDER PART
NUMBER
LT1637CMS8
T
= 150°C, θJA = 250°C/W
JMAX
MS8 PART
MARKING
Operating Temperature Range (Note 3) .. – 40°C to 85°C Specified Temperature Range (Note 4) ... –40°C to 85°C
Junction Temperature........................................... 150°C
Storage Temperature Range ................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
ORDER PART
NUMBER
LT1637CN8 LT1637CS8 LT1637IN8 LT1637IS8
T
= 150°C, θJA = 130°C/W (N8)
JMAX
= 150°C, θJA = 190°C/W (S8)
T
JMAX
S8 PART
MARKING
LTIE
1637 1637I
Consult factory for Military grade parts.
3V 5VAUD ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. VS = 3V, 0V; VS = 5V, 0V; V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
I
OS
I
B
e
n
i
n
2
Input Offset Voltage N8, S8 Packages 100 350 µV
Input Offset Voltage Drift (Note 9) N8, S8 Packages, – 40°C ≤ TA 85°C 13µV/°C
Input Offset Current 0.4 6.0 nA
Input Bias Current 20 50 nA
Input Noise Voltage 0.1Hz to 10Hz 0.6 µV Input Noise Voltage Density f = 1kHz 27 nV/√Hz Input Noise Current Density f = 1kHz 0.08 pA/√Hz
= V–,VCM = V
SHDN
= Half Supply unless otherwise specified. (Note 4)
OUT
70°C 550 µV
0°C T
A
–40°C ≤ T MS8 Package 100 350 µV
0°C T –40°C ≤ T
MS8 Package, – 40°C ≤ T
V
CM
V
CM
= 0V 0.1 nA
V
S
85°C 700 µV
A
70°C 750 µV
A
85°C 900 µV
A
85°C 26µV/°C
A
= 44V (Note 5) 2.5 µA
= 44V (Note 5) 23 60 µA
P-P
Page 3
LT1637
3V 5VAUD ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. VS = 3V, 0V; VS = 5V, 0V; V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
R
IN
C
IN
CMRR Common Mode Rejection Ratio VCM = 0V to (VCC – 1V) 88 110 dB
A
VOL
V
OL
V
OH
I
SC
PSRR Power Supply Rejection Ratio VS = 3V to 12.5V, VCM = VO = 1V 90 98 dB
I
S
I
SHDN
t
ON
t
OFF
t
SETTLING
GBW Gain-Bandwidth Product f = 10kHz 650 1000 kHz
SR Slew Rate AV = – 1, R
Input Resistance Differential 1 2.6 M
Input Capacitance 4pF Input Voltage Range 044V
(Note 5) V
Large-Signal Voltage Gain VS = 3V, VO = 500mV to 2.5V, RL = 10k 150 400 V/mV
Output Voltage Swing LOW No Load 38 mV
Output Voltage Swing HIGH VS = 3V, No Load 2.94 2.975 V
Short-Circuit Current (Note 2) VS = 3V, Short Output to Ground 10 14 mA
Minimum Supply Voltage 2.7 V
Reverse Supply Voltage I
Supply Current 190 250 µA
(Note 6)
Supply Current, SHDN V
Shutdown Pin Current V
Output Leakage Current V
Maximum Shutdown Pin Current V
Turn-On Time V
Turn-Off Time V
Settling Time 0.1% A
(Note 5) 0°C ≤ T
(Note 7) 0°C ≤ T
= V–, VCM = V
SHDN
= Half Supply unless otherwise specified. (Note 4)
OUT
Common Mode, V
= 0V to 44V (Note 8) 80 98 dB
CM
V
= 3V, 0°C ≤ TA 70°C 100 V/mV
S
= 3V, –40°C TA 85°C 75 V/mV
V
S
= 0V to 44V 0.7 1.4 M
CM
VS = 5V, VO = 500mV to 4.5V, RL = 10k 300 800 V/mV
= 5V, 0°C ≤ TA 70°C 200 V/mV
V
S
V
= 5V, –40°C TA 85°C 150 V/mV
S
I
= 5mA 325 700 mV
SINK
V
S
V
S
= 5V, I
= 3V, I
= 10mA 580 1300 mV
SINK
= 5mA 2.25 2.67 V
SOURCE
VS = 5V, No Load 4.94 4.975 V V
= 5V, I
S
= 3V, Short Output to V
V
S
= 10mA 3.80 4.45 V
SOURCE
CC
15 45 mA
VS = 5V, Short Output to Ground 15 22 mA
= 5V, Short Output to V
V
S
= –100µA 25 40 V
S
= 2V, No Load (Note 6) 312 µA
PIN5
= 0.3V, No Load (Note 6) 0.2 15 nA
PIN5
= 2V, No Load (Note 5) 1.0 5 µA
V
PIN5
V
= 3.3V 2.5 µA
PIN5
= 5V 4.3 µA
V
PIN5
= 2V, No Load (Note 6) 0.02 1 µA
PIN5
= 32V, No Load (Note 5) 20 150 µA
PIN5
= 5V to 0V, R
PIN5
= 0V to 5V, R
PIN5
= 1, ∆VO = 2V 9 µs
V
70°C 550 kHz
A
–40°C ≤ T
–40°C ≤ T
85°C 500 kHz
A
= 0.210 0.35 V/µs
L
70°C 0.185 V/µs
A
85°C 0.170 V/µs
A
CC
= 10k 45 µs
L
= 10k 3 µs
L
15 60 mA
295 µA
3
Page 4
LT1637
±15V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. V
= ±15V, V
S
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
I
OS
I
B
e
n
i
n
R
IN
C
IN
CMRR Common Mode Rejection Ratio VCM = –15V to 29V 80 110 dB
A
VOL
V
OL
V
OH
I
SC
PSRR Power Supply Rejection Ratio V
I
S
I
SHDN
V
L
V
H
t
ON
t
OFF
= 0V, V
CM
OUT
= 0V, V
= V– unless otherwise specified. (Note 4)
SHDN
Input Offset Voltage N8, S8 Packages 100 450 µV
70°C 650 µV
0°C T
A
–40°C ≤ T
85°C 800 µV
A
MS8 Package 100 450 µV
70°C 800 µV
0°C T
A
–40°C ≤ T
85°C 950 µV
A
Input Offset Voltage Drift (Note 9) N8, S8 Packages, – 40°C ≤ TA 85°C 13µV/°C
MS8 Package, – 40°C ≤ T
85°C 26µV/°C
A
Input Offset Current 16 nA Input Bias Current 17 50 nA Input Noise Voltage 0.1Hz to 10Hz 0.6 µV
P-P
Input Noise Voltage Density f = 1kHz 27 nV/√Hz Input Noise Current Density f = 1kHz 0.08 pA/√Hz Input Resistance Differential 1 3 M
Common Mode, V
= –15V to 14V 2200 M
CM
Input Capacitance 4pF Input Voltage Range –15 29 V
Large-Signal Voltage Gain V
= ±14V, R
O
0°C T –40°C ≤ T
= 10k 100 400 V/mV
L
70°C 75 V/mV
A
85°C 50 V/mV
A
Output Voltage Swing LOW No Load –14.997 –14.95 V
= 5mA –14.680 –14.25 V
I
SINK
= 10mA –14.420 –13.65 V
I
SINK
Output Voltage Swing HIGH No Load 14.9 14.967 V
I
= 5mA 14.2 14.667 V
SOURCE
= 10mA 13.7 14.440 V
I
SOURCE
Short-Circuit Current (Note 2) Short Output to GND ±25 ±31.7 mA
70°C ±20 mA
0°C T
A
–40°C ≤ T
= ±1.5V to ±22V 90 115 dB
S
85°C ±15 mA
A
Minimum Supply Voltage ±1.35 V Supply Current 230 300 µA
370 µA
Positive Supply Current, SHDN V
Shutdown Pin Current V
Maximum Shutdown Pin Current V
Output Leakage Current V
Shutdown Pin Input Low Voltage V
Shutdown Pin Input High Voltage V
Turn-On Time V
Turn-Off Time V
= – 20V, V
PIN5
= – 21.7V, V
PIN5
V
= – 20V, V
PIN5
= 32V, V
PIN5
= – 20V, V
PIN5
= ±22V – 21.7 –21.6 V
S
= ±22V – 20.8 –20.0 V
S
= – 10V to – 15V, R
PIN5
= – 15V to – 10V, R
PIN5
= ±22V, No Load 640 µA
S
= ±22V, No Load 0.3 15 nA
S
= ±22V, No Load 0.9 8 µA
S
= ±22V 20 150 µA
S
= ±22V, No Load 0.02 2 µA
S
= 10k 35 µs
L
= 10k 3 µs
L
4
Page 5
LT1637
±15V ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the specified temperature range, otherwise specifications are at TA = 25°C. V
= ±15V, V
S
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
GBW Gain-Bandwidth Product f = 10kHz 750 1100 kHz
SR Slew Rate AV = – 1, R
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.
Note 3: The LT1637 is guaranteed functional over the operating
temperature range of – 40°C to 85°C.
Note 4: The LT1637C is guaranteed to meet specified performance from
0°C to 70°C. The LT1637C is designed, characterized and expected to meet specified performance from –40°C to 85°C but is not tested or QA
sampled at these temperatures. The LT1637I is guaranteed to meet
specified performance from –40°C to 85°C.
= 0V, V
CM
OUT
= 0V, V
= V– unless otherwise specified. (Note 4)
SHDN
70°C 650 kHz
0°C T
A
–40°C ≤ T
0°C T –40°C ≤ T
85°C 600 kHz
A
= ∞, VO = ±10V, Measure at VO = ±5V 0.225 0.4 V/µs
L
70°C 0.200 V/µs
A
85°C 0.180 V/µs
A
Note 5: V V
S
Note 6: V V
S
Note 7: Guaranteed by correlation to slew rate at V V
S
Note 8: This specification implies a typical input offset voltage of 650µV at
V
CM
Note 9: This parameter is not 100% tested.
= 5V limits are guaranteed by correlation to VS = 3V and
S
= ±15V or VS = ±22V tests.
= 3V limits are guaranteed by correlation to VS = 5V and
S
= ±15V or VS = ±22V tests.
= ±15V and GBW at
= 3V and V
= ±15V tests.
S
S
= 44V and a maximum input offset voltage of 5.4mV at VCM = 44V.
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Supply Current vs Supply Voltage
400
350
300
T
250
200
150
SUPPLY CURRENT (µA)
100
50
0
0 10203040
TOTAL SUPPLY VOLTAGE (V)
= 125°C
A
T
= 25°C
A
T
= –55°C
A
1637 G01
Minimum Supply Voltage
400
300
200
100
0
T
= 125°C
A
–100
–200
–300
CHANGE IN INPUT OFFSET VOLTAGE (µV)
–400
1 2 3 4 5
0
TOTAL SUPPLY VOLTAGE (V)
T
= –55°C
A
T
= 25°C
A
1637 G02
Input Bias Current vs Common Mode Voltage
40
VS = 5V, 0V
30
20
10
T
= –55°C
0.12
0.08
0.04
INPUT BIAS CURRENT (µA)
0.04
0.08
A
T
= 125°C
A
T
= 25°C
0
4 4.2 4.4 4.6 4.8 5 10 20 30 40 50
A
COMMON MODE VOLTAGE (V)
1637 G03
5
Page 6
LT1637
TEMPERATURE (°C)
–50
SLEW RATE (V/µs)
25
1637 G12
–25 0 50 75 100 125
0.7
0.6
0.5
0.4
0.3
0.2
0.1
FALLING, V
S
= ±1.5V
FALLING, V
S
= ±15V
RISING, V
S
= ±15V
RISING, V
S
= ±1.5V
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Output Saturation Voltage vs Load Current (Output High)
1
VS = 5V, 0V
= 30mV
V
OD
0.1
OUTPUT SATURATION VOLTAGE (V)
0.01
0.0001 0.001
T
= 125°C
A
T
= 25°C
A
T
= –55°C
A
0.01 0.1 1 10 100
SOURCING LOAD CURRENT (mA)
0.1Hz to 10Hz Noise Voltage
V
= ±2.5V
S
1637 G04
Output Saturation Voltage vs Load Current (Output Low)
10
VS = 5V, 0V
= 30mV
V
OD
1
0.1
T
= 125°C
A
T
= 25°C
0.01
OUTPUT SATURATION VOLTAGE (V)
0.001
A
0.0001 0.001
T
= –55°C
A
0.01 0.1 1 10 100
SINKING LOAD CURRENT (mA)
Noise Voltage Density vs Frequency
70
V
= ±15V
S
60
50
1637 G05
Output Saturation Voltage vs Input Overdrive
100
VS = 5V, 0V
90
NO LOAD
80
70
60
50
40
30
20
OUTPUT SATURATION VOLTAGE (mV)
10
0
20
30
10 90
0
INPUT OVERDRIVE (mV)
40
OUTPUT HIGH
OUTPUT LOW
60
50
70
Input Noise Current vs Frequency
1.4
V
= ±15V
S
1.2
1.0
0.8
80
100
1637 G06
INPUT NOISE CURRENT DENSITY (pA/Hz)
0.6
0.4
0.2
0
1
10 100 1000
FREQUENCY (Hz)
1637 G09
40
NOISE VOLTAGE (200nV/DIV)
2
0
3
19
4
TIME (s)
6
7
8
5
10
1637 G07
Open-Loop Gain and Phase Shift vs Frequency Slew Rate vs Temperature
70
V
= ±2.5V
60
50
40
30
20
GAIN (dB)
10
0
–10
–20
–30
1k
GAIN
10k 100k 1M
FREQUENCY (Hz)
S
PHASE
120
100
80
60
40
20
0
1637 G10
30
INPUT NOISE VOLTAGE DENSITY (nV/Hz)
20
1
10 100 1000
FREQUENCY (Hz)
Gain-Bandwidth Product vs Temperature
1300
1200
PHASE SHIFT (DEG)
1100
1000
900
800
GAIN-BANDWIDTH PRODUCT (kHz)
700
–50
–25 0
V
= ±15V
S
V
= ±1.5V
S
50 100 125
25 75
TEMPERATURE (°C)
1637 G08
1637 G11
6
Page 7
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Gain-Bandwidth Product and Phase Margin vs Supply Voltage CMRR vs Frequency PSRR vs Frequency
1300
1250
1200
1150
1100
1050
GAIN-BANDWIDTH PRODUCT (kHz)
1000
515
0
PHASE MARGIN
GAIN BANDWIDTH
10
TOTAL SUPPLY VOLTAGE (V)
25 45
20
55
50
45
40
35
30
40
1637 G13
25
35
30
100
90
PHASE MARGIN (DEG)
80
70
60
50
40
30
20
10
COMMON MODE REJECTION RATIO (dB)
0
1k
V
= ±15V
S
V
= ±1.5V
S
10k 100k 1M
FREQUENCY (Hz)
1637 G14
90
V
= ±2.5V
S
80
70
60
50
40
30
NEGATIVE SUPPLY
20
10
0
POWER SUPPLY REJECTION RATIO (dB)
–10
1k
LT1637
POSITIVE SUPPLY
10k 100k 1M
FREQUENCY (Hz)
1637 G15
Gain-Bandwidth Product and Phase Margin vs Load Resistance
1400
V
= ±2.5V
S
1300
1200
1100
1000
900
800
GAIN-BANDWIDTH PRODUCT (kHz)
700
600
GAIN BANDWIDTH
1k
LOAD RESISTANCE ()
PHASE MARGIN
10k 100k
Settling Time to 0.1% vs Output Step
10
V
= ±15V
S
8
6
AV = 1
4
2
0
–2
OUTPUT STEP (V)
–4
–6
–8
–10
0
AV = 1
10
SETTLING TIME (µs)
AV = –1
AV = –1
20
Undistorted Output Swing
Output Impedance vs Frequency
50
45
40
35
30
25
20
15
10
1637 G16
10k
V
S
PHASE MARGIN (DEG)
1k
100
10
OUTPUT IMPEDANCE ()
1
0.1 100
= ±2.5V
AV = 100
AV = 10
AV = 1
1k 100k 1M10k
FREQUENCY (Hz)
1637 G17
Capacitive Load Handling, Overshoot vs Capacitive Load
100
V
= ±2.5V
S
90
NO OUTPUT COMPENSATION
80
70
60
50
40
OVERSHOOT (%)
30
20
10
30
40
1637 G19
0
10
AV = 1
100 1000 10000
CAPACITIVE LOAD (pF)
AV = 2
AV = 5
AV = 10
1637 G20
vs Frequency
35
V
= ±15V
s
30
)
25
P-P
20
15
10
OUTPUT SWING (V
V
= ±2.5V
s
5
0
100
1k 10k 100k
FREQUENCY (Hz)
DISTORTION 1%
= 1
A
V
Total Harmonic Distortion + Noise vs Frequency
10
VS = 3V, 0V
= 1.8V
V
OUT
=10k
L
AV = –1
AV = 1
100 10k 100k1k
P-P
FREQUENCY (Hz)
VCM = 1.2V
1
R
0.1
0.01
THD + NOISE (%)
0.001
0.0001 10
1637 G18
1637 G21
7
Page 8
LT1637
OUTPUT VOLTAGE (V
P-P
)
0.01
THD + NOISE (%)
1
10
023
1637 G23
0.001 1
0.1
RL = 10k V
CM
= HALF SUPPLY f = 1kHz FOR A
V
= –1, RG = 100k
AV = –1, VS = 3V, 0V
AV = 1 V
S
= ±1.5V
AV = 1 V
S
= 3V, 0V
AV = 1 V
S
= 3V, 0V
AV = –1 V
S
= ±1.5V
UW
TYPICAL PERFOR A CE CHARACTERISTICS
Total Harmonic Distortion + Noise vs Load Resistance
1
V
= ±1.5V
S
= ±0.9V
V
0.1
0.01
THD + NOISE (%)
0.001
0.0001
IN
VS = 3V, 0V V
IN
VS = 3V, 0V V
IN
100
LOAD RESISTANCE TO GROUND ()
Open-Loop Gain
A
B
C
(50µV/DIV)
A: RL = 2k B: RL = 10k
= 50k
C: R
CHANGE IN INPUT OFFSET VOLTAGE
L
–10V
OUTPUT VOLTAGE (5V/DIV)
0V 10V
VS = 3V TOTAL
= 1
A
V
= 1.8V
P-P
AT 1kHz
V
IN
= 0.6V TO 2.4V
= 0.3V TO 2.1V
1k 10k 100k
V
= ±15V
S
A
B
C
1637 G24
1637 G22
Large-Signal Response
= ±15V
V
S
AV = –1
10V
– 10V
Total Harmonic Distortion + Noise vs Output Voltage
Small-Signal Response
V
= ±15V
S
AV = 1
50mV
–50mV
1637 G25
1637 G26
U
APPLICATIO S I FOR ATIO
Supply Voltage
with a small capacitor (about 0.01µF) within an inch of the pin. When driving heavy loads an additional 4.7µF electro-
lytic capacitor should be used. When using split supplies, the same is true for the negative supply pin.
The LT1637 is protected against reverse battery voltages up to 25V. In the event a reverse battery condition occurs, the supply current is typically less than 1nA.
When operating the LT1637 on total supplies of 30V or
more, the supply must not be brought up faster than 1µs.
This is especially true if low ESR bypass capacitors are used. A series RLC circuit is formed from the supply lead
inductance and the bypass capacitor. 5 of resistance in
the supply or the bypass capacitor will dampen the tuned circuit enough to limit the rise time.
8
WUU
Inputs
The LT1637 has 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 0.9V or more below V+, the PNP input stage is active and the input bias current is typically –20nA. When the input voltage is about 0.5V or less from V+, the NPN input stage is operating and the input bias current is typically 80nA. Increases in temperature will cause the voltage at which operation switches from the PNP stage to the NPN stage to move towards V+. The input offset voltage of the NPN stage is untrimmed and is
typically 600µV.
Page 9
LT1637
U
WUU
APPLICATIO S I FOR ATIO
A Schottky diode in the collector of each NPN transistor of the NPN input stage allows the LT1637 to operate 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 23µA at room temperature. The input offset voltage is typically 600µV when operating
above V+. The LT1637 will operate with its input 44V above V– regardless of V+.
The inputs are protected against excursions as much as 22V below V– by an internal 1.3k resistor in series with each input and a diode from the input to the negative supply. There is no output phase reversal for inputs up to 5V below V–. There are no clamping diodes between the inputs and the maximum differential input voltage is 44V.
Output
The output voltage swing of the LT1637 is affected by input overdrive as shown in the typical performance curves. When monitoring input voltages within 100mV of V+, gain should be taken to keep the output from clipping.
The output of the LT1637 can be pulled up to 25V beyond V+ with less than 1nA of leakage current, provided that V is less than 0.5V.
The normally reverse biased substrate diode from the output to V– will cause unlimited currents to flow when the output is forced below V–. If the current is transient and limited to 100mA, no damage will occur.
The LT1637 is internally compensated to drive at least 200pF of capacitance under any output loading condi-
tions. A 0.22µF capacitor in series with a 150 resistor
between the output and ground will compensate these amplifiers for larger capacitive loads, up to 4700pF, at all output currents.
+
Lower load resistance increases the output crossover distortion, but has no effect on the input stage transition distortion. For lowest distortion the LT1637 should be operated single supply, with the output always sourcing current and with the input voltage swing between ground and (V+ – 0.9V). See the Typical Performance Character­istics curves.
Gain
The open-loop gain is less sensitive to load resistance when the output is sourcing current. This optimizes per­formance in single supply applications where the load is returned to ground. The typical performance photo of Open-Loop Gain for various loads shows the details.
Shutdown
The LT1637 can be shut down two ways: using the shutdown pin or bringing V+ to within 0.5V of V–. When V
+
is brought to within 0.5V of V– both the supply current and output leakage current drop to less than 10nA. When the shutdown pin is brought 1.2V above V–, the supply
current drops to about 3µA and the output leakage current is less than 1µA, independent of V
+
. In either case the input bias current is less than 0.1nA (even if the inputs are 44V above the negative supply).
The shutdown pin can be taken up to 32V above V–. The shutdown pin can be driven below V–, however the pin current through the substrate diode should be limited with an external resistor to less than 10mA.
Input Offset Nulling
The input offset voltage can be nulled by placing a 10k potentiometer between Pins 1 and 8 with its wiper to V
(see Figure 1). The null range will be at least ±3mV.
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. Of course, if the op amp is operating inverting there is no common mode induced distortion. When the LT1637 switches between input stages there is significant nonlinearity in the CMRR.
LT1637
8
1
10k
V
Figure 1. Input Offset Nulling
1637 F01
9
Page 10
LT1637
+
LT1637
5k
1M
5V TO 44V
3V
100k
0.5
LAMP
ON/OFF
OUT
1637 TA05
OUT = 0V FOR GOOD BULB
3V FOR OPEN BULB
SI PLIFIED
SHDN
5
R1 1M
Q3
10µA
WW
SCHE ATIC
R2 6k
–IN
Q2
+IN
R3
1.3k
2
R4
1.3k
3
Q9
Q11
D1 D2
Q12
Q14
+
7
Q25
Q26
V
6
OUT
Q13Q1
Q15Q10
Q16
Q18
Q17
Q19
Q23
D3
Q20
Q21
Q22
Q24
Q4
Q6
Q5
Q7
Q8
U
TYPICAL APPLICATIO S
Positive Supply Rail Current Sense
+
V
200
5V
0.2
200
LOAD
I
LOAD
V
+
OUT
LT1637
= (2)(I
LOAD
Q1 2N3904
0V TO 4.3V
2k
1637 TA02
)
D4
D5
Optional Output Compensation for
Capacitive Loads Greater Than 200pF
V
IN
+
LT1637
0.22µF
150
1637 TA03
R5 7k
R7 400
C
4700pF
L
R6 7k
R8 400
81
NULLNULL
Lamp Outage Detector
1637 SS
4
V
10
Over-The-Top Comparator with Hysteresis
(0V TO 44V)
(0V TO 44V)
10k
IN1
10k
IN2
HYSTERESIS =
V
CC
100
3V TO 44V
+
LT1637
1M
1M
2N5087
2N5210
1637 TA04
1M
1M
Over-The-Top Current Sense
0.1V TO 44V R1
200
5V
R
LOAD
S
0.2
I
LOAD
V
OUT
I
LOAD
+
LT1637
V
=
(RS)(R2/R1)
OUT
Q1 2N3904
R2 2k
1637 TA06
V
OUT
(0V TO 4.3V)
Page 11
PACKAGE DESCRIPTIO
0.007 (0.18)
0.021
± 0.006
(0.53 ± 0.015)
* 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
° – 6° TYP
0
U
Dimensions in inches (millimeters) unless otherwise noted.
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
0.118 ± 0.004* (3.00 ± 0.102)
0.193 ± 0.006
(4.90 ± 0.15)
SEATING
PLANE
0.040
± 0.006
(1.02 ± 0.15)
0.012
(0.30)
0.0256
REF
(0.65)
BSC
0.034 ± 0.004
(0.86 ± 0.102)
0.006 ± 0.004
(0.15 ± 0.102)
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
8
7
12
6
5
0.118 ± 0.004**
4
3
LT1637
(3.00 ± 0.102)
MSOP (MS8) 1098
0.300 – 0.325
(7.620 – 8.255)
0.065
(1.651)
0.009 – 0.015
(0.229 – 0.381)
+0.035
0.325 –0.015
+0.889
8.255
()
–0.381
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
TYP
0.045 – 0.065
(1.143 – 1.651)
0.100 (2.54)
BSC
8-Lead Plastic Small Outline (Narrow 0.150)
0.010 – 0.020
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
*
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
× 45°
0.016 – 0.050
(0.406 – 1.270)
0.053 – 0.069
(1.346 – 1.752)
0°– 8° TYP
0.014 – 0.019
(0.355 – 0.483)
TYP
0.130 ± 0.005
(3.302 ± 0.127)
0.125
(3.175)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
S8 Package
(LTC DWG # 05-08-1610)
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
0.020
(0.508)
MIN
0.228 – 0.244
(5.791 – 6.197)
0.255 ± 0.015* (6.477 ± 0.381)
87 6
12
0.189 – 0.197* (4.801 – 5.004)
7
8
1
2
0.400*
(10.160)
MAX
6
3
5
4
3
N8 1098
5
0.150 – 0.157** (3.810 – 3.988)
4
SO8 1298
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.
11
Page 12
LT1637
U
TYPICAL APPLICATIO S
3V
V
SAMPLE
0V
DROOP (LT1636 BUFFER): 200mV/s DROOP INTO HIGH IMPEDANCE : LESS THAN 0.625mV/s
Sample-and-Hold
3V
+
LT1636
3V
V
OUT
1637 TA07
V
+
IN
LT1637
SHDN
150
0.22µF
MUX Amplifier Waveforms
0.2ms/DIV
1637 TA08
5kHz AT 4V
10kHz AT 2V
INPUT SELECT 1kHz AT 5V
MUX Amplifier
5V
V
IN1 P-P
V
IN2
P–P
P–P
SHDN
74HC04
+
LT1637
SHDN
LT1637
+
V
OUT
V
OUT
2V/DIV
5V
INPUT
SELECT
5V/DIV
1637 TA09
RELATED PARTS
PART NUMBER DESCRIPTION COMMENTS
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Input and Output Op Amps
LT1782 Micropower, Over-The-Top, SOT-23, Rail-to-Rail SOT-23, 800µV V
OS(MAX)
, I
=55µA (Max),
S
Input and Output Op Amp Gain-Bandwidth = 200kHz, Shutdown Pin
LT1783 1.2MHz, Over-The-Top, Micropower, Rail-to-Rail SOT-23, 800µV V
OS(MAX)
, I
=300µA (Max),
S
Input and Output Op Amp Gain-Bandwidth = 1.2MHz, Shutdown Pin
OS(MAX)
OS(MAX)
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
www.linear-tech.com
1637f LT/TP 0100 4K • PRINTED IN USA
LINEAR TECHNOLOGY CORPORATION 1999
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