LT1797
1
1797fc
For more information www.linear.com/LT1797
Typical applicaTion
FeaTures DescripTion
10MHz, Rail-to-Rail
Input and Output
Op Amp in SOT-23
The LT
®
1797 is a unity-gain stable 10MHz op amp available
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/µs.
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
included 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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
ThinSOT and Over-The-Top are trademarks of Analog Devices, Inc. All other trademarks are the
property of their respective owners.
Fast Compact –48V Current Sense
applicaTions
n Rail-to-Rail Input and Output
n Small SOT-23 Package
n Gain Bandwidth Product: 10MHz
n –40°C to 85°C Operation
n Slew Rate: 2.25V/µs
n Low Input Offset Voltage: 1.5mV Max
n High Output Current: 25mA Min
n Specified on 3V, 5V and ±5V Supplies
n High Voltage Gain: 1000V/mV 10k Load
n High CMRR: 96dB Typ
n High PSRR: 90dB Typ
n Input Bias Current: 300nA Max
n Input Offset Current: 25nA Max
n Low Profile (1mm) SOT-23 (ThinSOT™) Package
n Portable Instrumentation
n Rail-to-Rail Buffer Amplifiers
n Low Voltage Signal Processing
n Driving A/D Converters
n Battery-Powered Systems
Small-Signal Response
–
+
LT1797
0.1µF
R1 REDUCES Q1 DISSIPATION
Q1
FMMT493
0.003Ω
1% 3W
BZX84C6V8
VZ = 6.8V
–48V SUPPLY
(–42V TO –56V)
3.3k
0805
×3
30.1Ω
1%
ISENSE +–
R1
4.7k VS = 3V
1k
1%
VOUT = 3V – 0.1Ω • ISENSE
ISENSE = 0A TO 30A
ACCURACY ≈ 3%
–48V LOAD
1797 TA01
SETTLES TO 1% IN 2µs,
1V OUTPUT STEP
VOUT
1797 TA01b
VS = ±2.5V
AV = 1
RL = 10k
LT1797
2
1797fc
For more information www.linear.com/LT1797
pin conFiguraTionabsoluTe MaxiMuM raTings
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
(Note 1)
4
5
3
1
OUT
V–
+IN
V+
–IN
TOP VIEW
S5 PACKAGE
5-LEAD PLASTIC TSOT-23
2
+–
TJMAX = 150°C, θJA = 250°C/W
orDer inForMaTion
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LT1797CS5#PBF LT1797CS5#TRPBF LTLM 5-Lead Plastic TSOT-23 –40°C to 85°C
LT1797IS5#PBF LT1797IS5#TRPBF LTTL 5-Lead Plastic TSOT-23 –40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 3V, 0V; VS = 5V, 0V, VCM = VOUT = half supply, pulse power tested,
unless otherwise specified. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
1 1.5
2.5
3.0
mV
mV
mV
Input Offset Voltage Drift (Note 4) l5 20 µV/°C
IBInput Bias Current VCM = V–
VCM = V+
l
l
–300 –150
50
100
nA
nA
Input Bias Current Drift l0.1 nA/°C
IOS Input Offset Current VCM = V–
VCM = V+
l
l
10
10
25
25
nA
nA
Input Noise Voltage 0.1Hz to 10Hz 1.5 µVP-P
enInput Noise Voltage Density f = 10kHz 20 nV/√Hz
inInput Noise Current Density f = 10kHz
f = 10kHz, VCM = VCC – 0.3V
0.23
0.15
pA/√Hz
pA/√Hz
RIN Input Resistance Differential
Common Mode, VCM = 0V to VS – 1.3V
200 330
100
kΩ
MΩ
CIN Input Capacitance 4 pF
CMRR Common Mode Rejection Ratio VCM = 0V to VS – 1.3V
VS = 5V, VCM = 0V to 5V
VS = 3V, VCM = 0V to 3V
l
l
l
82
64
60
96
72
68
dB
dB
dB
http://www.linear.com/product/LT1797#orderinfo
LT1797
3
1797fc
For more information www.linear.com/LT1797
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VS = 3V, 0V; VS = 5V, 0V, VCM = VOUT = half supply, pulse power tested,
unless otherwise specified. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Voltage Range l0 VSV
AVOL Large-Signal Voltage Gain VS = 3V, VO = 0.5V to 2.5V, RL = 10k
l
200
150
1000 V/mV
V/mV
VS = 5V, VO = 0.5V to 4.5V, RL = 10k
l
400
300
1000 V/mV
V/mV
PSRR Power Supply Rejection Ratio VS = 2.7V to 12V, VCM = VO = 1V l80 90 dB
Minimum Supply Voltage l2.5 2.7 V
VOL Output Voltage Swing LOW No Load, Input Overdrive = 30mV
ISINK = 5mA
ISINK = 10mA
l
l
l
8
80
150
30
160
250
mV
mV
mV
VOH Output Voltage Swing HIGH No Load, Input Overdrive = 30mV
ISOURCE = 5mA
ISOURCE = 10mA, VS = 5V
ISOURCE = 10mA, VS = 3V
l
l
l
l
VS – 0.14
VS – 0.30
VS – 0.39
VS – 0.59
VS – 0.05
VS – 0.2
VS – 0.3
VS – 0.3
V
V
V
V
ISC Short-Circuit Current VS = 5V
VS = 3V
25
15
45
25
mA
mA
ISSupply Current
l
1.1 1.5
2.0
mA
mA
GBW Gain Bandwidth Product (Note 5) f = 100kHz
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
6.0
5.0
4.5
10 MHz
MHz
MHz
SR Slew Rate (Note 5) AV = –1
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
1.3
1.1
1.0
2.25 V/µs
V/µs
V/µs
trOutput Rise Time 10% to 90%, 0.1V Step, RL = 10k 55 ns
tfOutput Fall Time 10% to 90%, 0.1V Step, RL = 10k 55 ns
tSSettling Time VS = 5V, ΔVOUT = 2V to 0.1%, AV = –1 1.6 µs
THD Distortion VS = 3V, VOUT = 1.8VP-P, AV = 1, RL = 10k, f = 1kHz 0.001 %
FPBW Full-Power Bandwidth (Note 6) VOUT = 2VP-P 360 kHz
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
VS = ±5V, VCM = 0V, VOUT = 0V, pulse power tested unless otherwise specified. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VOS Input Offset Voltage
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
1 1.5
2.5
3.0
mV
mV
mV
Input Offset Voltage Drift (Note 4) l5 20 µV/°C
IBInput Bias Current VCM = V–
VCM = V+
l
l
–300 –150
50
100
nA
nA
Input Bias Current Drift l0.1 nA/°C
IOS Input Offset Current VCM = V–
VCM = V+
l
l
10
10
25
25
nA
nA
Input Noise Voltage 0.1Hz to 10Hz 1 µVP-P
enInput Noise Voltage Density f = 10kHz 20 nV/√Hz
inInput Noise Current Density f = 10kHz
f = 10kHz, VCM = 4.7V
0.23
0.15
pA/√Hz
pA/√Hz
LT1797
4
1797fc
For more information www.linear.com/LT1797
elecTrical characTerisTics
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C.VS = ±5V, VCM = 0V, VOUT = 0V, pulse power tested unless otherwise
specified. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
RIN Input Resistance Differential
Common Mode, VCM = –5V to 3.7V
200 330
100
kΩ
MΩ
CIN Input Capacitance 4 pF
Input Voltage Range l–5 5 V
CMRR Common Mode Rejection Ratio VCM = –5V to 3.7V
VCM = –5V to 5V
l
l
78
66
96
76
dB
dB
AVOL Large-Signal Voltage Gain VO = ±4V, RL = 10k
l
400
300
1000 V/mV
V/mV
VOL Output Voltage Swing LOW No Load, Input Overdrive = 30mV
ISINK = 5mA
ISINK = 10mA
l
l
l
–4.99
–4.92
–4.85
–4.97
–4.87
–4.79
V
V
V
VOH Output Voltage Swing HIGH No Load, Input Overdrive = 30mV
ISOURCE = 5mA
ISOURCE = 10mA
l
l
l
4.84
4.70
4.61
4.95
4.80
4.70
V
V
V
ISC Short-Circuit Current (Note 2) Short to GND 30 50 mA
PSRR Power Supply Rejection Ratio VS = ±1.35V to ±6V l80 90 dB
ISSupply Current
l
1.40 2.25
3.00
mA
mA
GBW Gain Bandwidth Product f = 100kHz
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
6.5
5.5
5.0
11 MHz
MHz
MHz
SR Slew Rate AV = –1, RL = ∞, VO = ±4V, Measured at VO = ±2V
0°C ≤ TA ≤ 70°C
–40°C ≤ TA ≤ 85°C
l
l
1.50
1.25
1.10
2.50 V/µs
V/µs
V/µs
trOutput Rise Time 10% to 90%, 0.1V Step, RL = 10k 55 ns
tfOutput Fall Time 10% to 90%, 0.1V Step, RL = 10k 55 ns
tSSettling Time ΔVOUT = 4V to 0.1%, AV = 1 2.6 µs
FPBW Full-Power Bandwidth (Note 6) VOUT = 8VP-P 100 kHz
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
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: VS = 3V limit guaranteed by correlation to 5V tests.
Note 6: Full-power bandwidth is calculated from the slew rate:
FPBW = SR/2πVP
LT1797
5
1797fc
For more information www.linear.com/LT1797
Output Saturation Voltage
vs Load Current (Output High)
Output Saturation Voltage
vs Load Current (Output Low)
Output Saturation Voltage
vs Input Overdrive
Output Short-Circuit Current
vs Temperature 0.1Hz to 10Hz Noise Voltage
Input Noise Voltage Density
vs Frequency
Supply Current vs Supply Voltage Minimum Supply Voltage
Input Bias Current
vs Common Mode Voltage
Typical perForMance characTerisTics
TOTAL SUPPLY VOLTAGE (V)
0
0
SUPPLY CURRENT (mA)
0.2
0.6
0.8
1.0
6789
1.8
1797 G01
0.4
1 2 3 4 5 10 11 12
1.2
1.4
1.6 TA = 125°C
TA = 25°C
TA = –55°C
TOTAL SUPPLY VOLTAGE (V)
–300
INPUT OFFSET VOLTAGE CHANGE (µV)
–100
100
300
–200
0
200
1.0 1.5 2.0 3.0 4.0
1797 G02
5.00.50 2.5 3.5 4.5
TA = 125°C TA = –55°C
TA = 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
5.00.50 1.5 2.5 3.5 4.5
VS = 5V, 0V
TA = 25°C
TA = 125°C
TA = –55°C
SOURCING LOAD CURRENT (A)
1µ
0.01
OUTPUT SATURATION VOLTAGE (V)
0.1
1
100µ10µ 10m1m
1797 G04
VS = ±2.5V
VOD = 30mV
TA = 25°C
TA = 125°C
TA = –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
VS = ±2.5V
IOUT = 0
OUTPUT HIGH
OUTPUT LOW
SINKING LOAD CURRENT (A)
0.01
OUTPUT SATURATION VOLTAGE (V)
0.1
1µ 100µ 1m 10m
1797 G05
0.001 10µ
1
TA = 125°C
VS = ±2.5V
VOD = 30mV
TA = 25°C
TA = –55°C
TEMPERATURE (°C)
–50
OUTPUT CURRENT (mA)
40
45
50
25 75
1797 G07
35
30
–25 0 50 100 125
25
20
VS = ±2.5V
SOURCING CURRENT
SINKING CURRENT
TIME (SEC)
NOISE VOLTAGE (1µV/DIV)
2 4 6 8
1797 G08
1010 3 5 7 9
VS = ±5V
FREQUENCY (Hz)
20
INPUT NOISE VOLTAGE DENSITY (nV/√Hz)
40
60
80
100
10 1k 10k 100k
1797 G09
0100
VS = ±2.5V
LT1797
6
1797fc
For more information www.linear.com/LT1797
Typical perForMance characTerisTics
Slew Rate vs Temperature
Gain Bandwidth Product and
Phase Margin vs Supply Voltage
PSRR vs Frequency CMRR vs Frequency
Gain Bandwidth Product and
Phase Margin vs RF and RG
Output Impedance vs Frequency
Input Noise Current Density
vs Frequency
Gain and Phase Shift
vs Frequency
Gain Bandwidth Product
vs Temperature
FREQUENCY (Hz)
INPUT NOISE CURRENT DENSITY (pA/√Hz)
10 1k 10k 100k
1797 G10
100
VS = ±2.5V
1.2
1.0
0.8
0.6
0.4
0.2
0
FREQUENCY (Hz)
0
GAIN (dB)
PHASE (DEG)
60
70
–10
–20
50
20
40
30
10
10k 1M 10M 100M
1797 G11
–30
–40
80
100
–60
–80
60
0
40
20
–20
–100
100k
VS = ±2.5V
PHASE
GAIN
TEMPERATURE (°C)
–50
GAIN BANDWIDTH PRODUCT (MHz)
11.5
25
1797 G12
10.0
9.0
–25 0 50
8.5
8.0
12.0
11.0
10.5
9.5
75 100 125
VS = ±5V
VS = ±2.5V
f = 100kHz
TEMPERATURE (°C)
–50 –25
1.0
SLEW RATE (V/µs)
2.0
3.5
050 75
1797 G13
1.5
3.0
2.5
25 100 125
RISING
FALLING
VS = ±2.5V
TOTAL SUPPLY VOLTAGE (V)
0
8
GAIN BANDWIDTH PRODUCT (MHz)
PHASE MARGIN (DEG)
10
12
9
11
13
2468
1797 G14
101 35 7 9 11 12
35
30
45
55
40
50
60
PHASE MARGIN
GAIN BANDWIDTH PRODUCT
f = 100kHz
RF = RG = 1k
RF = RG = (Ω)
1k
10
GAIN BANDWIDTH PRODUCT (MHz)
PHASE MARGIN (DEG)
12
14
10k 100k
1797 G15
11
13
20
40
60
10
30
50
PHASE MARGIN
GAIN BANDWIDTH PRODUCT
VS = ±5V
FREQUENCY (Hz)
20
POWER SUPPLY REJECTION RATIO (dB)
80
90
10
0
70
40
60
50
30
1k 100k 1M 10M
1797 G16
–10 10k
VS = ±2.5V
NEGATIVE SUPPLY
POSITIVE SUPPLY
FREQUENCY (Hz)
40
COMMON MODE REJECTION RATIO (dB)
100
110
30
20
90
60
80
70
50
1k 100k 1M 10M
1797 G17
10 10k
VS = ±2.5V
FREQUENCY (Hz)
100 1k
0.01
OUTPUT IMPEDANCE (Ω)
1
100
10k 100k 1M 10M
1797 G18
0.1
10 GAIN = 100
GAIN = 10
VS = ±2.5V
LT1797
7
1797fc
For more information www.linear.com/LT1797
Typical perForMance characTerisTics
Undistorted Output Swing
vs Frequency
Total Harmonic Distortion + Noise
vs Frequency
Total Harmonic Distortion + Noise
vs Load Resistance
Total Harmonic Distortion + Noise
vs Output Voltage Amplitude Large-Signal Response Small-Signal Response
Open-Loop Gain
Settling Time
to 0.1% vs Output Step
Capacitive Load Handling
Overshoot vs Capacitive Load
OUTPUT VOLTAGE (V)
–5
CHANGE IN INPUT OFFSET VOLTAGE (50µV/DIV)
1797 G19
–4 –3 –2 –1 012345
VS = ±5V
RL = 50k
RL = 2k
RL = 10k
SETTLING TIME (µs)
1.0
OUTPUT STEP (V)
4
3
2
1
0
–1
–2
–3
– 4 2.6
1797 G20
1.4 1.8 2.2 3.02.41.2 1.6 2.0 2.8
AV = 1
AV = 1
AV = –1
VS = ±5V
AV = –1
CAPACITIVE LOAD (pF)
10
20
OVERSHOOT (%)
25
30
35
40
100 1000 10000
1797 G21
15
10
5
0
45
50
AV = 1
AV = 5
AV = 10
AV = 2
VS = ±2.5V
FREQUENCY (Hz)
2
OUTPUT SWING (V
P-P
)
4
6
8
10
100 10k 100k 1M
1797 G22
01k
12
1
3
5
7
9
11 AV = 1
VS = ±5V
VS = ±1.5V
FREQUENCY (Hz)
10 100
0.0001
THD + NOISE (%)
0.01
1
1k 10k 100k
1797 G23
0.001
0.1
AV = –1
AV = 1
RL = 10k
VS = 3V, 0V
VOUT = 1.8VP-P
VCM = 1V
LOAD RESISTANCE TO GROUND (kΩ)
0.01
THD + NOISE (%)
0.1
1
10
1 10 100
1797 G24
0.0010.1
VS = 3V, 0V
VIN = 1.8VP-P
VCM = 1.5V
VS = 3V, 0V
VIN = 1.8VP-P
VCM = 1V
VS = 3V TOTAL
AV = 1
f = 1kHz
OUTPUT VOLTAGE (VP-P)
0.01
THD + NOISE (%)
1
10
0 2 3
1797 G25
0.001 1
0.1
f = 1kHz
VCM = HALF SUPPLY
RL = 10k
AV = –1
VS = 3V, 0V
AV = 1
VS = 3V, 0V
AV = –1
VS = ±1.5V
AV = 1
VS = ±1.5V
1797 G26
VS = ±2.5V
AV = 1
1797 G27
VS = ±2.5V
AV = 1
RL = 10k
LT1797
8
1797fc
For more information www.linear.com/LT1797
applicaTions inForMaTion
Supply Voltage
The positive supply pin of the LT1797 should be bypassed
with a small capacitor (about 0.1µF) 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.
Inputs
The LT1797 is fully functional for an input signal range
from the negative supply to the positive supply. Figure 1
shows a simplified schematic of the amplifier. The input
stage consists of two differential amplifiers, a PNP stage
Q3/Q4 and an NPN stage Q1/Q2 that are active over dif-
ferent ranges of input common mode voltage. The PNP
differential pair is active for input common mode voltages
VCM between the negative supply to approximately 1.3V
below the positive supply. As VCM moves closer toward
the positive supply, the transistor QB1 will steer the tail
current I1 to the current mirror Q5/Q6, activating the
NPN differential pair and the PNP pair becomes inactive
for the rest of the input common mode range up to the
positive supply.
The input offset voltage and the input bias current are
dependent on which input stage is active. The input offset
voltage is trimmed on a single 5V supply with the common
mode at 1/2 supply and is typically 1mV with the PNP stage
active. The input offset of the NPN stage is untrimmed and
is typically 1.5mV. The input bias current polarity depends
on the input common mode voltage. When the PNP dif-
ferential pair is active, the input bias currents flow out of
the input pins. They flow in the opposite direction when
the NPN input stage is active. The offset error due to the
input bias currents can be minimized by equalizing the
noninverting and inverting source impedance.
The input stage of the LT1797 incorporates phase reversal
protection to prevent false outputs from occurring when
the inputs are driven up to 5V beyond the rails. Protective
resistors are included in the input leads so that current
does not become excessive when the inputs are forced
beyond the supplies or when a large differential signal is
applied.
Output
The output is configured with a pair of complementary
common emitter stages Q19/Q20, which enable the output
to swing from rail-to-rail. The output voltage swing of the
LT1797 is affected by input overdrive as shown in the Typi-
cal Performance Characteristics. When monitoring input
voltages within 50mV of V+ or within 8mV of V–, some
gain should be taken to keep the output from clipping. The
output of the LT1797 can deliver large load currents; the
short-circuit current limit is typically 50mA at ±5V. Take
care to keep the junction temperature of the IC below the
absolute maximum rating of 150°C. The output of the
amplifier has reverse biased diodes to each supply. If the
output is forced beyond either supply, unlimited current
will flow through these diodes.
The LT1797 can drive capacitive loads up to 200pF on
a single 5V supply in a unity gain configuration. When
there is a need to drive larger capacitive loads, a resistor
of a couple hundred ohms should be connected between
the output and the capacitive load. The feedback should
still be taken from the output so that the resistor isolates
the capacitive load to ensure stability. The low input bias
current of the LT1797 makes it possible to use high value
feedback resistors to set the gain. However, care must
be taken to insure that the pole formed by the feedback
resistors and the total capacitance at the inverting input
does not degrade stability.
LT1797
9
1797fc
For more information www.linear.com/LT1797
applicaTions inForMaTion
Distortion
There are two main contributors to distortion in op amps:
output crossover distortion as the output transitions from
sourcing to sinking current and distortion caused by non-
linear common mode rejection. If the op amp is operating
in the inverting mode, there is no common mode induced
distortion. If the op amp is operating in the PNP input stage
(input is not within 1.3V of V+), the CMRR is very good,
typically 96dB. When the LT1797 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 LT1797 should be operated single
supply, with the output always sourcing current and with
the input voltage swing between ground and (V+ – 1.3V).
See the Typical Performance Characteristic curves.
1797 F01
Q18
Q1
Q3 Q4
QB1
Q7
Q11
Q13
Q9
Q6
Q2
Q12
Q8
Q14
Q10
Q5
Q17
Q15
Q19
Q20
Q16
R1
R3 R4
R7 R8
R5
R6
R2
D1 D2
–IN
+IN
BIAS
I1
OUT
+1 +1 CM
C1
C2
I3I2
I4 I5
I6
I7
1/2 SUPPLY
Figure 1. Simplified Schematic
LT1797
10
1797fc
For more information www.linear.com/LT1797
Typical applicaTions
Single Supply Hi-Gain 80kHz Photodiode Amplifier
–
+
LT1797
3V
3V
R2
1k
R4
1k
R5
100k
R6
330Ω
R3
10k
R1
100k
C1
0.1µF
C2
0.1µF
C3
1000pF
CP*
1797 TA02
*CP = SUM OF PHOTODIODE CAPACITANCE, PARASITIC LAYOUT
CAPACITANCE AND LT1797 INPUT CAPACITANCE ≅10pF.
TRANSIMPEDANCE GAIN: AZ = 10MΩ.
R6, C3 LIMIT THE NOISE BANDWIDTH TO 500kHz.
OUTPUT NOISE ≅1.8mVRMS.
R1, CP AND LT1797 GBW SET UPPER LIMIT ON BANDWIDTH.
R4, C2 SET LOWER 1.6kHz LIMIT ON GAIN OF 101.
PHOTODIODE
SFH213FA
LT1797
12
1797fc
For more information www.linear.com/LT1797
package DescripTion
1.50 – 1.75
(NOTE 4)
2.80 BSC
0.30 – 0.45 TYP
5 PLCS (NOTE 3)
DATUM ‘A’
0.09 – 0.20
(NOTE 3) S5 TSOT-23 0302
PIN ONE
2.90 BSC
(NOTE 4)
0.95 BSC
1.90 BSC
0.80 – 0.90
1.00 MAX 0.01 – 0.10
0.20 BSC
0.30 – 0.50 REF
NOTE:
1. DIMENSIONS ARE IN MILLIMETERS
2. DRAWING NOT TO SCALE
3. DIMENSIONS ARE INCLUSIVE OF PLATING
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR
5. MOLD FLASH SHALL NOT EXCEED 0.254mm
6. JEDEC PACKAGE REFERENCE IS MO-193
3.85 MAX
0.62
MAX
0.95
REF
RECOMMENDED SOLDER PAD LAYOUT
PER IPC CALCULATOR
1.4 MIN
2.62 REF
1.22 REF
S5 Package
5-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1635)
Please refer to http://www.linear.com/product/LT1797#packaging for the most recent package drawings.
LT1797
13
1797fc
For more information www.linear.com/LT1797
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
revision hisTory
REV DATE DESCRIPTION PAGE NUMBER
B 6/10 Updated the last Feature.
Updated the package description in the Pin Configuration section.
Updated VOH in the Electrical Characteristics section.
Replaced the package drawing in the Package Description section.
1
2
3
12
C 7/17 Corrected Simplified Schematic 9
(Revision history begins at Rev B)
LT1797
14
1797fc
For more information www.linear.com/LT1797
LINEAR TECHNOLOGY CORPORATION 2000
LT 0717 REV C • PRINTED IN USA
www.linear.com/LT1797
relaTeD parTs
Typical applicaTion
1MHz Photodiode Transimpedance Amplifier Response of Photodiode Amplifier
Rise Time vs Supply Voltage (600mV Output Step)
Supply Voltage 10% to 90% Rise Time
±1.5V 830ns
±2.5V 800ns
±5V 700ns
PART NUMBER DESCRIPTION COMMENTS
LT1630/LT1631 Dual/Quad 30MHz, 10V/µs Rail-to-Rail Input
and Output Op Amps
High DC Accuracy, 525µV VOS(MAX), 70mA Output Current,
Max Supply Current 4.4mA per Amp
LT1638/LT1639 Dual/Quad 1.2MHz, 0.4V/µs, Over-The-Top™ Micropower
Rail-to-Rail Input and Output Op Amps
170µA Supply Current, Single Supply Input Range –0.4V to 44V,
Rail-to-Rail Input and Output
LT1783 Micropower Over-The-Top SOT-23 Rail-to-Rail Input and
Output Op Amp
SOT-23 Package, Micropower 220µA per Amplifier,
Rail-to-Rail Input and Output, 1.2MHz Gain Bandwidth
LT1880 SOT-23 Rail-to-Rail Output, Picoamp Input Current
Precision Op Amp
150µV Maximum Offset Voltage, 900pA Maximum Bias Current,
1.1MHz Gain Bandwidth, –40°C to 85°C Temperature Range
–
+
LT1797
PHOTODIODE
SFH213FA
SIEMENS/INFINEON
VS = ±1.5V TO ±5V
3pF
100k
V+
V–
1797 TA04 1797 TA04b
2µs/DIV
100mV/DIV
