1
LT1797
s
Rail-to-Rail Input and Output
s
Small SOT-23 Package
s
Gain Bandwidth Product: 10MHz
s
40
C to 85
C Operation
s
Slew Rate: 2.25V/
s
s
Low Input Offset Voltage: 1.5mV Max
s
High Output Current: 25mA Min
s
Specified on 3V, 5V and
5V Supplies
s
High Voltage Gain: 1000V/mV 10k Load
s
High CMRR: 88dB Min
s
High PSRR: 80dB Min
s
Input Bias Current: 300nA Max
s
Input Offset Current: 25nA Max
The LT
1797 is a unity-gain stable 10MHz op amp avail-
able in the small SOT-23 package that operates on all
single and split supplies with a total voltage of 2.7V to 12V.
The amplifier draws 1mA of quiescent current and has a
slew rate of 2.25V/
s.
The input common mode range of the LT1797 includes
both rails, making it ideal for current sensing applications.
The input stage incorporates phase reversal protection to
prevent false outputs from occurring when the inputs are
driven beyond the supplies. Protective resistors are in-
cluded in the input leads so that current does not become
excessive when the inputs are forced above or below the
supplies.
The output of the LT1797 can swing to within 50mV of V
+
and 8mV of V
without drawing excess current in either
condition. The amplifier can drive loads up to 25mA and
still maintain rail-to-rail capability.
The LT1797 op amp is available in the space saving 5-lead
SOT-23 package.
s
Portable Instrumentation
s
Rail-to-Rail Buffer Amplifiers
s
Low Voltage Signal Processing
s
Driving A/D Converters
s
Battery-Powered Systems
10MHz, Rail-to-Rail
Input and Output
Op Amp in SOT-23
, LTC and LT are registered trademarks of Linear Technology Corporation.
+
LT1797
0.1
F
R1 REDUCES Q1 DISSIPATION
Q1
FMMT493
0.003
1% 3W
BZX84C6V8
V
Z
= 6.8V
48V SUPPLY
(42V TO 56V)
3.3k
0805
3
30.1
1%
I
SENSE
+
R1
4.7k
V
S
= 3V
1k
1%
V
OUT
= 3V 0.1
I
SENSE
I
SENSE
= 0A TO 30A
ACCURACY
3%
48V LOAD
1797 TA01
SETTLES TO 1% IN 2
s,
1V OUTPUT STEP
V
OUT
Fast Compact 48V Current Sense
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
N
U
2
LT1797
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
OS
Input Offset Voltage
1
1.5
mV
0
C
T
A
70
C
q
2.5
mV
40
C
T
A
85
C
q
3.0
mV
Input Offset Voltage Drift (Note 4)
q
5
20
V/
C
I
B
Input Bias Current
V
CM
= V
q
300
150
nA
V
CM
= V
+
q
50
100
nA
Input Bias Current Drift
q
0.1
nA/
C
I
OS
Input Offset Current
V
CM
= V
q
10
25
nA
V
CM
= V
+
q
10
25
nA
Input Noise Voltage
0.1Hz to 10Hz
1.5
V
P-P
e
n
Input Noise Voltage Density
f = 10kHz
20
nV/
Hz
i
n
Input Noise Current Density
f = 10kHz
0.23
pA /
Hz
f = 10kHz, V
CM
= V
CC
0.3V
0.15
pA /
Hz
R
IN
Input Resistance
Differential
200
330
k
Common Mode, V
CM
= 0V to V
S
1.2V
100
M
C
IN
Input Capacitance
4
pF
CMRR
Common Mode Rejection Ratio
V
CM
= 0V to V
S
1.2V
q
88
96
dB
V
CM
= 0V to V
S
q
64
72
dB
Input Voltage Range
q
0
V
S
V
A
VOL
Large-Signal Voltage Gain
V
S
= 3V, V
O
= 0.5V to 2.5V, R
L
= 10k
200
1000
V/mV
q
150
V/mV
V
S
= 5V, V
O
= 0.5V to 4.5V, R
L
= 10k
400
1000
V/mV
q
300
V/mV
T
JMAX
= 150
C,
JA
= 250
C/ W
(Note 1)
Total Supply Voltage (V
+
to V
) ........................... 12.6V
Input Differential Voltage ..................................... 12.6V
Input Current .....................................................
10mA
Output Short-Circuit Duration (Note 2) ........ Continuous
Operating Temperature Range
(Note 3) ............................................. 40
C to 85
C
Specified Temperature Range ................. 40
C to 85
C
Junction Temperature ........................................... 150
C
Storage Temperature Range ................ 65
C to 150
C
Lead Temperature (Soldering, 10 sec)................. 300
C
Consult factory for parts specified with wider operating temperature ranges.
The
q
denotes specifications which apply over the specified temperature range, otherwise specifications are T
A
= 25
C.
V
S
= 3V, 0V; V
S
= 5V, 0V, V
CM
= V
OUT
= half supply, pulse power tested, unless otherwise specified. (Note 3)
4
5
3
1
OUT
V
+IN
V
+
IN
TOP VIEW
S5 PACKAGE
5-LEAD PLASTIC SOT-23
2
+
LT1797CS5
LT1797IS5
ORDER PART
NUMBER
S5 PART MARKING
LTLM
LTTL
ABSOLUTE AXI U RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
ELECTRICAL CHARACTERISTICS
3
LT1797
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
PSRR
Power Supply Rejection Ratio
V
S
= 2.7V to 12V, V
CM
= V
O
= 1V
q
80
90
dB
Minimum Supply Voltage
q
2.5
2.7
V
V
OL
Output Voltage Swing LOW
No Load, Input Overdrive = 30mV
q
8
15
mV
I
SINK
= 5mA
q
80
160
mV
I
SINK
= 10mA
q
150
250
mV
V
OH
Output Voltage Swing HIGH
No Load, Input Overdrive = 30mV
q
V
S
0.14 V
S
0.05
V
I
SOURCE
= 5mA
q
V
S
0.30 V
S
0.2
V
I
SOURCE
= 10mA
q
V
S
0.39 V
S
0.3
V
I
SC
Short-Circuit Current
V
S
= 5V
25
45
mA
V
S
= 3V
15
25
mA
I
S
Supply Current
1.1
1.5
mA
q
2.0
mA
GBW
Gain Bandwidth Product (Note 5)
f = 100kHz
6.0
10
MHz
0
C
T
A
70
C
q
5.0
MHz
40
C
T
A
85
C
q
4.5
MHz
SR
Slew Rate (Note 5)
A
V
= 1
1.3
2.25
V/
s
0
C
T
A
70
C
q
1.1
V/
s
40
C
T
A
85
C
q
1.0
V/
s
t
r
Output Rise Time
10% to 90%, 0.1V Step, R
L
= 10k
55
ns
t
f
Output Fall Time
10% to 90%, 0.1V Step, R
L
= 10k
55
ns
t
S
Settling Time
V
S
= 5V,
V
OUT
= 2V to 0.1%, A
V
= 1
1.6
s
THD
Distortion
V
S
= 3V, V
OUT
= 1.8V
P-P
, A
V
= 1, R
L
= 10k, f = 1kHz
0.001
%
FPBW
Full-Power Bandwidth (Note 6)
V
OUT
= 2V
P-P
360
kHz
The
q
denotes specifications which apply over the specified temperature range, otherwise specifications are T
A
= 25
C.
V
S
= 3V, 0V; V
S
= 5V, 0V, V
CM
= V
OUT
= half supply, pulse power tested, unless otherwise specified. (Note 3)
The
q
denotes specifications which apply over the specified temperature range, otherwise specifications are T
A
= 25
C.
V
S
=
5V, V
CM
= 0V, V
OUT
= 0V, pulse power tested unless otherwise specified. (Note 3)
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
OS
Input Offset Voltage
1
1.5
mV
0
C
T
A
70
C
q
2.5
mV
40
C
T
A
85
C
q
3.0
mV
Input Offset Voltage Drift (Note 4)
q
5
20
V/
C
I
B
Input Bias Current
V
CM
= V
q
300
150
nA
V
CM
= V
+
q
50
100
nA
Input Bias Current Drift
q
0.1
nA/
C
I
OS
Input Offset Current
V
CM
= V
q
10
25
nA
V
CM
= V
+
q
10
25
nA
Input Noise Voltage
0.1Hz to 10Hz
1
V
P-P
e
n
Input Noise Voltage Density
f = 10kHz
20
nV/
Hz
i
n
Input Noise Current Density
f = 10kHz
0.23
pA/
Hz
f = 10kHz, V
CM
= 4.7V
0.15
pA/
Hz
R
IN
Input Resistance
Differential
200
330
k
Common Mode, V
CM
= 5V to 3.8V
100
M
C
IN
Input Capacitance
4
pF
Input Voltage Range
q
5
5
V
ELECTRICAL CHARACTERISTICS
4
LT1797
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
CMRR
Common Mode Rejection Ratio
V
CM
= 5V to 3.8V
q
83
96
dB
V
CM
= 5V to 5V
q
66
76
dB
A
VOL
Large-Signal Voltage Gain
V
O
=
4V, R
L
= 10k
400
1000
V/mV
q
300
V/mV
V
OL
Output Voltage Swing LOW
No Load, Input Overdrive = 30mV
q
4.99
4.98
V
I
SINK
= 5mA
q
4.92
4.87
V
I
SINK
= 10mA
q
4.85
4.79
V
V
OH
Output Voltage Swing HIGH
No Load, Input Overdrive = 30mV
q
4.84
4.95
V
I
SOURCE
= 5mA
q
4.70
4.80
V
I
SOURCE
= 10mA
q
4.61
4.70
V
I
SC
Short-Circuit Current (Note 2)
Short to GND
30
50
mA
PSRR
Power Supply Rejection Ratio
V
S
=
1.35V to
6V
q
80
90
dB
I
S
Supply Current
1.40
2.25
mA
q
2.70
mA
GBW
Gain Bandwidth Product
f = 100kHz
6.5
11
MHz
0
C
T
A
70
C
q
5.5
MHz
40
C
T
A
85
C
q
5.0
MHz
SR
Slew Rate
A
V
= 1, R
L
=
, V
O
=
4V, Measured at V
O
=
2V
1.50
2.50
V/
s
0
C
T
A
70
C
q
1.25
V/
s
40
C
T
A
85
C
q
1.10
V/
s
t
r
Output Rise Time
10% to 90%, 0.1V Step, R
L
= 10k
55
ns
t
f
Output Fall Time
10% to 90%, 0.1V Step, R
L
= 10k
55
ns
t
S
Settling Time
V
OUT
= 4V to 0.1%, A
V
= 1
2.6
s
FPBW
Full-Power Bandwidth (Note 6)
V
OUT
= 8V
P-P
100
kHz
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 LT1797C is guaranteed to meet 0
C to 70
C specifications
and is designed, characterized and expected to meet the extended
temperature limits, but is not tested at 40
C and 85
C. The LT1797I is
guaranteed to meet specified performance from 40
C to 85
C.
Note 4: This parameter is not 100% tested.
Note 5: V
S
= 3V limit guaranteed by correlation to 5V tests.
Note 6: Full-power bandwidth is calculated from the slew rate:
FPBW = SR/2
V
P
The
q
denotes specifications which apply over the specified temperature range, otherwise specifications are T
A
= 25
C.
V
S
=
5V, V
CM
= 0V,V
OUT
= 0V, pulse power tested unless otherwise specified. (Note 3)
ELECTRICAL CHARACTERISTICS
5
LT1797
Output Saturation Voltage
vs Load Current (Output High)
Output Saturation Voltage
vs Load Current (Output Low)
SINKING LOAD CURRENT (A)
0.01
OUTPUT SATURATION VOLTAGE (V)
0.1
1
100
1m
10m
1797 G05
0.001
10
1
T
A
= 125
C
V
S
=
2.5V
V
OD
= 30mV
T
A
= 25
C
T
A
= 55
C
Output Saturation Voltage
vs Input Overdrive
Output Short-Circuit Current
vs Temperature
0.1Hz to 10Hz Noise Voltage
Input Noise Voltage Density
vs Frequency
TEMPERATURE (
C)
50
OUTPUT CURRENT (mA)
40
45
50
25
75
1797 G07
35
30
25
0
50
100
125
25
20
V
S
=
2.5V
SOURCING CURRENT
SINKING CURRENT
TIME (SEC)
NOISE VOLTAGE (1
V/DIV)
2
4
6
8
1797 G08
10
1
0
3
5
7
9
V
S
=
5V
FREQUENCY (Hz)
20
INPUT NOISE VOLTAGE DENSITY (nV/
Hz)
40
60
80
100
10
1k
10k
100k
1797 G09
0
100
V
S
=
2.5V
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
SOURCING LOAD CURRENT (A)
1
0.01
OUTPUT SATURATION VOLTAGE (V)
0.1
1
100
10
10m
1m
1797 G04
V
S
=
2.5V
V
OD
= 30mV
T
A
= 25
C
T
A
= 125
C
T
A
= 55
C
INPUT OVERDRIVE (mV)
0
OUTPUT SATURATION VOLTAGE (mV)
60
80
100
120
140
30
50
100
1797 G06
40
20
0
70
90
110
130
150
50
30
10
10 20
40
60 70 80 90
V
S
=
2.5V
I
OUT
= 0
OUTPUT HIGH
OUTPUT LOW
Supply Current vs Supply Voltage
Minimum Supply Voltage
Input Bias Current
vs Common Mode Voltage
TOTAL SUPPLY VOLTAGE (V)
300
INPUT OFFSET VOLTAGE CHANGE (
V)
100
100
300
200
0
200
1.0 1.5 2.0
3.0
4.0
1797 G02
5.0
0.5
0
2.5
3.5
4.5
T
A
= 125
C
T
A
= 55
C
T
A
= 25
C
COMMON MODE VOLTAGE (V)
200
INPUT BIAS CURRENT (nA)
100
0
100
150
50
50
1.0
2.0
3.0
4.0
1797 G03
5.0
0.5
0
1.5
2.5
3.5
4.5
V
S
= 5V, 0V
T
A
= 25
C
T
A
= 125
C
T
A
= 55
C
TOTAL SUPPLY VOLTAGE (V)
0
0
SUPPLY CURRENT (mA)
0.2
0.6
0.8
1.0
6
7
8
9
1.8
1797 G01
0.4
1
2
3
4
5
10 11 12
1.2
1.4
1.6
T
A
= 125
C
T
A
= 25
C
T
A
= 55
C
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