1
LT1672/LT1673/LT1674
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATION
U
2µA Max, AV 5 Single, Dual
and Quad Over-The-Top Precision
Rail-to-Rail Input and Output Op Amps
Gain of 5 Stable
Low Supply Current: 2
µ
A Max per Amplifier
Rail-to-Rail Input and Output
Low Offset Voltage: 375
µ
V Max
Over-The-Top
TM
Inputs Operate Above V
+
Gain Bandwidth Product: 12kHz
Wide Supply Range: 2.2V to 36V
Single Supply Input Range: –0.3V to 36V
Low Input Bias Current: 250pA
Low Input Offset Current: 20pA
High A
VOL
: 100V/mV Minimum Driving 100k Load
Output Sources and Sinks 500µA Load Current
Reverse Battery Protected to 18V
The LT
®
1672/LT1673/LT1674 are ultralow power
(I
S
2µA) decompensated (A
V
5) op amps with preci-
sion specifications. The extremely low supply current is
combined with excellent amplifier specifications: input
offset voltage is 375µV maximum with a typical drift of
only 0.4µV/°C, input offset current is 100pA maximum. A
minimum open-loop gain (A
VOL
) of 100V/mV ensures that
gain errors are small. The devices’ characteristics change
little over the supply range of 2.2V to ±15V. Supply
rejection is 90dB and the common mode rejection ratio is
90dB. Operation is specified for 3V, 5V and ±15V supplies.
Reverse battery protection (–18V min) and inputs that
operate above the positive supply make the LT1672/
LT1673/LT1674 easy to use in harsh environments.
The low bias currents and offset current of the amplifier
permit the use of megohm level source resistors without
introducing significant errors. Voltage noise at 4µV
P-P
is
remarkably low considering the low supply current. For
unity gain stable versions of these amplifiers, see the
LT1494/LT1495/LT1496.
The LT1672 is available in the 8-pin MSOP, PDIP and SO
packages. The LT1673 is available in plastic 8-pin PDIP
and SO-8 packages with the standard dual op amp pinout.
The LT1674 is available in 14-pin PDIP and SO packages.
Battery- or Solar-Powered Systems
Portable Instrumentation
Remote Sensor Amplifier
Micropower Filter
Photodiode Amplifier
High Impedance Circuits
Single Supply, 60µW Precision Instrumentation Amplifier TC VOS Distribution
, LTC and LT are registered trademarks of Linear Technology Corporation.
100k*
100k* 5V
5V
1M
0.0047µF
A
V
= 100
BANDWIDTH = 1kHz
CMRR = 65dB AT 120Hz
*500V TRANSIENT PROTECTION
TOTAL SUPPLY CURRENT = 12µA
+
1M
1M
100k
100k1M
1M V
OUT
5V
LT1389-2.5
1672/3/4 TA01
LT1672
1000pF
110k
110k
V
IN1
V
IN2
+
+
1/2 LT1673
1/2 LT1673
TC V
OS
(µV/°C)
–1.5
UNITS
80
70
60
50
40
30
20
10
00.9
1672/3/4 TA02
0.9 0.3 0.3 1.5
120 AMPLIFIERS
V
S
= ±2.5V
–40°C to 85°C
Over-The-Top is a trademark of Linear Technology Corporation.
2
LT1672/LT1673/LT1674
S8 PART MARKING
Total Supply Voltage (V
+
to V
) .............................. 36V
Differential Input Voltage ......................................... 36V
Input Current ...................................................... ±10mA
Output Short-Circuit Duration.......................Continuous
Operating Temperature Range (Note 2) .. 40°C to 85°C
ORDER PART
NUMBER
T
JMAX
= 150°C, θ
JA
= 150°C/ W (N8)
T
JMAX
= 150°C, θ
JA
= 190°C/ W (S8)
1
2
3
4
8
7
6
5
TOP VIEW
OUT A
–IN A
+IN A
V
V
+
OUT B
–IN B
+IN B
N8 PACKAGE
8-LEAD PDIP S8 PACKAGE
8-LEAD PLASTIC SO
B
A
S8 PART MARKING
1673
1673I
LT1672CMS8
LT1672IMS8
ABSOLUTE AXI U RATI GS
WWWU
PACKAGE/ORDER I FOR ATIO
UU
W
Specified Temperature Range (Note 3)... 40°C to 85°C
Storage Temperature Range ................. 65°C to 150°C
Junction Temperature...........................................150°C
Lead Temperature (Soldering, 10 sec).................. 300°C
(Note 1)
TOP VIEW
S PACKAGE
14-LEAD PLASTIC SO
N PACKAGE
14-LEAD PDIP
1
2
3
4
5
6
7
14
13
12
11
10
9
8
OUT A
IN A
+IN A
V
+
+IN B
IN B
OUT B
OUT D
IN D
+IN D
V
+IN C
IN C
OUT C
A
B
D
C
ORDER PART
NUMBER
LT1674CN
LT1674CS
LT1674IN
LT1674IS
T
JMAX
= 150°C, θ
JA
= 110°C/ W (N)
T
JMAX
= 150°C, θ
JA
= 150°C/ W (S)
ORDER PART
NUMBER
MS8 PART MARKING
LTFH
LTFJ
LT1673CN8
LT1673CS8
LT1673IN8
LT1673IS8
1
2
3
4
NC
–IN
+IN
V
8
7
6
5
NC
V
+
OUT
NC
TOP VIEW
MS8 PACKAGE
8-LEAD PLASTIC MSOP
T
JMAX
= 150°C, θ
JA
= 250°C/W
LT1672CN8
LT1672CS8
LT1672IN8
LT1672IS8
ORDER PART
NUMBER
1672
1672I
1
2
3
4
8
7
6
5
TOP VIEW
NC
V
+
OUT
NC
NC
–IN
+IN
V
S8 PACKAGE
8-LEAD PLASTIC SO
N8 PACKAGE
8-LEAD PDIP
T
JMAX
= 150°C, θ
JA
= 130°C/W (N8)
T
JMAX
= 150°C, θ
JA
= 190°C/W (S8)
Consult factory for parts specified with wider operating temperature ranges.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage V
S
= 5V 150 375 µV
V
S
= 3V 200 475 µV
V
S
= 5V, MS8 Package 150 475 µV
V
S
= 3V, MS8 Package 200 575 µV
I
B
Input Bias Current (Note 5) 250 1000 pA
V
CM
= 10V (Note 6) 180 360 nA
I
OS
Input Offset Current (Note 5) 20 100 pA
Input Noise Voltage 0.1Hz to 10Hz 4 µV
P-P
TA = 25°C, VS = 5V, 0V; VS = 3V, 0V; VCM = VO = half supply, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
3
LT1672/LT1673/LT1674
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
e
n
Input Noise Voltage Density f = 100Hz 185 nV/Hz
i
n
Input Noise Current Density f = 100Hz 10 fA/Hz
A
VOL
Large-Signal Voltage Gain V
S
= 5V, V
O
= 0.25V to 4.5V, R
L
= 100k 100 500 V/mV
V
S
= 3V, V
O
= 0.25V to 2.5V, R
L
= 100k 50 250 V/mV
Input Voltage Range 0 36 V
CMRR Common Mode Rejection Ratio V
CM
= 0V to 4V, V
S
= 5V 90 106 dB
V
CM
= 0V to 10V, V
S
= 5V 74 95 dB
PSRR Power Supply Rejection Ratio V
S
= 2.2V to 12V, V
CM
= V
O
= 0.5V 90 99 dB
Minimum Operating Supply Voltage 2.1 2.2 V
V
OL
Output Voltage Swing LOW No Load 50 100 mV
I
SINK
= 100µA 210 410 mV
V
OH
Output Voltage Swing HIGH No Load V
+
– 0.07 V
+
– 0.035 V
I
SOURCE
= 100µAV
+
– 0.32 V
+
– 0.160 V
I
SC
Short-Circuit Current (Note 5) 0.7 1.3 mA
I
S
Supply Current per Amplifier (Note 6) 1.5 2 µA
Reverse Supply Voltage I
S
= 10µA per Amplifier –18 V
SR Slew Rate A
V
= –5, V
S
= ±10V 1.6 5 V/ms
GBW Gain Bandwidth Product f = 100Hz 12 kHz
TA = 25°C, VS = 5V, 0V; VS = 3V, 0V; VCM = VO = half supply, unless otherwise noted.
ELECTRICAL CHARACTERISTICS
The denotes the specifications which apply over the temperature range of 0°C TA 70°C. VS = 5V, 0V; VS = 3V, 0V;
VCM = VO = half supply, unless otherwise noted. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage V
S
= 5V 175 425 µV
V
S
= 3V 225 525 µV
V
S
= 5V, MS8 Package 175 525 µV
V
S
= 3V, MS8 Package 225 625 µV
V
OS
TC Input Offset Voltage Drift (Note 4) 0.4 2 µV/°C
I
B
Input Bias Current (Note 5) 250 1200 pA
V
CM
= 10V (Note 6) 240 500 nA
I
OS
Input Offset Current (Note 5) 20 120 pA
A
VOL
Large-Signal Voltage Gain V
S
= 5V, V
O
= 0.25V to 4.5V, R
L
= 100k 75 280 V/mV
V
S
= 3V, V
O
= 0.25V to 2.5V, R
L
= 100k 40 150 V/mV
Input Voltage Range 0.2 36 V
CMRR Common Mode Rejection Ratio V
CM
= 0.2V to 4V, V
S
= 5V 89 106 dB
V
CM
= 0.2V to 10V, V
S
= 5V 64 85 dB
PSRR Power Supply Rejection Ratio V
S
= 2.4V to 12V, V
CM
= V
O
= 0.5V 89 99 dB
Minimum Operating Supply Voltage 2.3 2.4 V
V
OL
Output Voltage Swing LOW No Load 55 110 mV
I
SINK
= 100µA225 450 mV
V
OH
Output Voltage Swing HIGH No Load V
+
– 0.08 V
+
– 0.04 V
I
SOURCE
= 100µAV
+
– 0.36 V
+
– 0.18 V
I
SC
Short-Circuit Current (Note 5) 0.6 1.1 mA
I
S
Supply Current per Amplifier (Note 6) 1.9 2.8 µA
4
LT1672/LT1673/LT1674
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage 200 575 µV
MS8 Package 200 675 µV
I
B
Input Bias Current 25 1000 pA
I
OS
Input Offset Current 20 100 pA
A
VOL
Large-Signal Voltage Gain V
O
= ±10V, R
L
= 100k 100 360 V/mV
Input Voltage Range 15 21 V
CMRR Common Mode Rejection Ratio V
CM
= –15V to 14V 100 120 dB
PSRR Power Supply Rejection Ratio V
S
= ±5V to ±15V 96 120 dB
V
OL
Output Voltage Swing LOW R
L
= 1M –14.85 –14.70 V
R
L
= 100k –14.75 –14.50 V
V
OH
Output Voltage Swing HIGH R
L
= 1M 14.78 14.89 V
R
L
= 100k 14.62 14.81 V
I
SC
Short-Circuit Current 0.7 1.5 mA
I
S
Supply Current per Amplifier 1.9 2.8 µA
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage V
S
= 5V 200 475 µV
V
S
= 3V 250 575 µV
V
S
= 5V, MS8 Package 200 575 µV
V
S
= 3V, MS8 Package 250 675 µV
V
OS
TC Input Offset Voltage Drift (Note 4) 0.4 2 µV/°C
I
B
Input Bias Current (Note 5) 250 1700 pA
V
CM
= 10V (Note 6) 275 750 nA
I
OS
Input Offset Current (Note 5) 20 170 pA
A
VOL
Large-Signal Voltage Gain V
S
= 5V, V
O
= 0.25V to 4.5V, R
L
= 100k 55 215 V/mV
V
S
= 3V, V
O
= 0.25V to 2.5V, R
L
= 100k 30 115 V/mV
Input Voltage Range 0.2 36 V
CMRR Common Mode Rejection Ratio V
CM
= 0.2V to 4V, V
S
= 5V 88 106 dB
V
CM
= 0.2V to 10V, V
S
= 5V 62 75 dB
PSRR Power Supply Rejection Ratio V
S
= 2.7V to 12V, V
CM
= V
O
= 0.5V 88 99 dB
Minimum Operating Supply Voltage 2.6 2.7 V
V
OL
Output Voltage Swing LOW No Load 60 120 mV
I
SINK
= 100µA245 490 mV
V
OH
Output Voltage Swing HIGH No Load V
+
– 0.10 V
+
– 0.05 mV
I
SOURCE
= 100µAV
+
– 0.38 V
+
– 0.19 mV
I
SC
Short-Circuit Current (Note 5) 0.4 0.9 mA
I
S
Supply Current per Amplifier (Note 6) 2.1 3.1 µA
The denotes the specifications which apply over the temperature range of –40°C TA 85°C. VS = 5V, 0V; VS = 3V, 0V;
VCM = VO = half supply, unless otherwise noted. (Note 3)
ELECTRICAL CHARACTERISTICS
TA = 25°C, VS = ±15V, VCM = VO = 0V, unless otherwise noted.
5
LT1672/LT1673/LT1674
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage 250 675 µV
MS8 Package 250 775 µV
I
B
Input Bias Current 250 1700 pA
I
OS
Input Offset Current 20 170 pA
A
VOL
Large-Signal Voltage Gain V
O
= ±10V, R
L
= 100k 50 200 V/mV
Input Voltage Range 14.8 21 V
CMRR Common Mode Rejection Ratio V
CM
= –14.8V to 14V 96 114 dB
PSRR Power Supply Rejection Ratio V
S
= ±5V to ±15V 92 120 dB
V
OL
Output Voltage Swing LOW R
L
= 1M –14.83 –14.66 V
R
L
= 100k –14.72 –14.44 V
V
OH
Output Voltage Swing HIGH R
L
= 1M 14.74 14.87 V
R
L
= 100k 14.54 14.77 V
I
SC
Short-Circuit Current 0.4 1.1 mA
I
S
Supply Current per Amplifier 2.8 4.2 µA
ELECTRICAL CHARACTERISTICS
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: The LT1672C/LT1673C/LT1674C and LT1672I/LT1673I/LT1674I
are guaranteed functional over the Operating Temperature Range of –40°C
to 85°C.
Note 3: The LT1672C/LT1673C/LT1674C are guaranteed to meet specified
performance from 0°C to 70°C. The LT1672C/LT1673C/LT1674C are
designed, characterized and expected to meet specified performance from
–40°C to 85°C but are not tested or QA sampled at these temperatures.
The LT1672I/LT1673I/LT1674I are guaranteed to meet specified
performance from –40°C to 85°C.
Note 4: This parameter is not 100% tested.
Note 5: V
S
= 5V limit guaranteed by correlation to V
S
= 3V and V
S
= ±15V
tests.
Note 6: V
S
= 3V limit guaranteed by correlation to V
S
= 5V and V
S
= ±15V
tests.
The denotes the specifications which apply over the temperature range of –40°C TA 85°C, VS = ±15V, VCM = VO = 0V,
unless otherwise noted. (Note 3)
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
OS
Input Offset Voltage 225 625 µV
MS8 Package 225 725 µV
I
B
Input Bias Current 250 1200 pA
I
OS
Input Offset Current 20 120 pA
A
VOL
Large-Signal Voltage Gain V
O
= ±10V, R
L
= 100k 60 240 V/mV
Input Voltage Range 14.8 21 V
CMRR Common Mode Rejection Ratio V
CM
= –14.8V to 14V 98 120 dB
PSRR Power Supply Rejection Ratio V
S
= ±5V to ±15V 94 120 dB
V
OL
Output Voltage Swing LOW R
L
= 1M –14.84 –14.67 V
R
L
= 100k –14.73 –14.46 V
V
OH
Output Voltage Swing HIGH R
L
= 1M 14.76 14.88 V
R
L
= 100k 14.58 14.79 mV
I
SC
Short-Circuit Current 0.6 1.3 mA
I
S
Supply Current per Amplifier 2.4 3.5 µA
The denotes the specifications which apply over the temperature range of 0°C TA 70°C, VS = ±15V, VCM = VO = 0V,
unless otherwise noted. (Note 3)
6
LT1672/LT1673/LT1674
TYPICAL PERFORMANCE CHARACTERISTICS
UW
Output Saturation Voltage
vs Load Current (Output Low) Input Bias Current
vs Common Mode Voltage
Output Saturation Voltage
vs Load Current (Output High)
Noise Current Spectrum
Gain and Phase Shift
vs Frequency Noise Voltage Spectrum
LOAD CURRENT (µA)
0.1
10
SATURATION VOLTAGE (mV)
100
1000
101 1000100
1672/3/4 G04
V
S
= 5V, 0V
T
A
= 85°C
T
A
= –40°C
T
A
= 25°C
LOAD CURRENT (µA)
0.1
10
SATURATION VOLTAGE (mV)
100
1000
101 1000100
1672/3/4 G05
V
S
= 5V, 0V
T
A
= 85°C
T
A
= –40°C
T
A
= 25°C
COMMON MODE VOLTAGE (V)
0
INPUT BIAS CURRENT (nA)
100
200
300
8
1672/3/4 G06
1.5
0.5
0.5 246
1–1 9
35710
V
S
= 5V, 0V T
A
= 85°C
T
A
= 85°C
T
A
= 25°C
T
A
= –40°C
T
A
= –40°C
T
A
= 25°C
FREQUENCY (Hz)
1
0
NOISE VOLTAGE (nV/Hz)
50
100
150
200
300
10 100
1672/3/4 G08
250
V
S
= ±2.5V
FREQUENCY (Hz)
1
0
CURRENT NOISE (fA/Hz)
20
40
60
80
10 100
1672/3/4 G09
100 V
S
= ±2.5V
Distribution of Input
Offset Voltage Supply Current vs Temperature Minimum Supply Voltage
TOTAL SUPPLY VOLTAGE (V)
1
CHANGE IN OFFSET VOLTAGE (µV)
100
150
200
5
1672/3/4 G03
50
–50
0
234
T
A
= 85°C
T
A
= –40°C
T
A
= 25°C
TEMPERATURE (°C)
–40
SUPPLY CURRENT PER AMPLIFIER (µA)
3.0
2.5
2.0
1.5
1.0
0.5
020 60
1672/3/4 G02
–20 0 40 80 100
V
S
= ±2.5V
V
S
= ±15V
INPUT OFFSET VOLTAGE (µV)
–400
PERCENT OF UNITS (%)
20
18
16
14
12
10
8
6
4
2
0–200 0100
1672/73/74 G01
–300 –100 200 300 400
VS = 5V, 0V
LT1672/73/74
5600 AMPLIFIERS
FREQUENCY (Hz)
100
VOLTAGE GAIN (dB)
90
80
70
60
50
40
30
20
10
0
–10
120
100
80
60
40
20
0
–20
–40
–60
–80
1k 10k
1672/3/4 G07
PHASE
GAIN
VS = ±2.5V
PHASE SHIFT (DEG)
7
LT1672/LT1673/LT1674
Power Supply Rejection Ratio
vs Frequency
Common Mode Rejection Ratio
vs Frequency
Warm-Up Drift vs Time Open-Loop Gain
VS = 5V, 0V Open-Loop Gain
VS = ±15V
Output Impedance vs Frequency
TYPICAL PERFORMANCE CHARACTERISTICS
UW
FREQUENCY (Hz)
100
COMMON MODE REJECTIO RATIO (dB)
1k 10k 20k
1672/3/4 G13
V
S
= ±2.5V
100
90
80
70
60
50
40
30
20
10
0
FREQUENCY (Hz)
10
POWER SUPPLY REJECTION RATIO (dB)
100
90
80
70
60
50
40
30
20
10
0100 1k 10k
1672/3/4 G14
V
S
= ±2.5V
+PSRR
–PSRR
1672/3/4 G15
FREQUENCY (Hz)
10
0.1
OUTPUT IMPEDANCE (k)
1
10
100
100 1k 10k
A
V
= 10
A
V
= 5
V
S
= ±2.5V
TIME AFTER POWER-UP (SEC)
0
OFFSET VOLTAGE CHANGE (µV)
40
20
30
10
0
–10
–20
–30
– 40 160
1672/3/4 G16
40 80 120 20014020 60 100 180
V
S
= ±15V
V
S
= ±2.5V
OUTPUT VOLTAGE (V)
0
OFFSET VOLTAGE CHANGE (µV)
–5
0
5
35
1672/3/4 G17
–10
–15
–20 12 4
10
15
20
6
V
S
= 5V, 0V
R
L
= 1M
R
L
= 100k
0.1Hz to 10Hz
Output Voltage Noise
Gain Bandwidth and Phase
Margin vs Supply Voltage Capacitive Load Handling
SUPPLY VOLTAGE (V)
0
FREQUENCY (kHz)
16
14
12
10
8
6
80
70
60
50
40
30
510 15 20
1672/3/4 G10
25 30
PHASE MARGIN
GBW
PHASE MARGIN (DEG)
MEASURED AT
A
V
= 5
TIME (1s/DIV)
OUTPUT VOLTAGE (2µV/DIV)
1672/3/4 G07
V
S
= ±15V
V
CM
= 0V
CAPACITIVE LOAD (pF)
10
OVERSHOOT (%)
80
70
60
50
40
30
20
10
0100 1k 10k
1672/3/4 G12
V
S
= ±2.5V
A
V
= 5
A
V
= 10
OUTPUT VOLTAGE (V)
20 –15
OFFSET VOLTAGE CHANGE (µV)
0
40
20
1672/3/4 G18
–40
–80 –10 5 0 5 1510
80
–20
20
–60
60
R
L
= 100k
V
S
= ±15V
R
L
= 1M
8
LT1672/LT1673/LT1674
Start-Up Characteristics
Micropower op amps are sometimes not micropower
during start-up, wreaking havoc on low current supplies.
In the worst case, there may not be enough supply current
available to take the system up to nominal voltages. Figure
1 is a graph of LT1673 supply current vs supply voltage
for the three limit cases of input offset that could occur
during start-up. The circuits are shown in Figure 2. One
circuit creates a positive offset, forcing the output to come
up saturated high. Another circuit creates a negative
offset, forcing the output to come up saturated low, while
the last brings up the output at half supply. In all cases, the
supply current is well behaved. Supply current is highest
with the output forced high, so if one amplifier is unused,
it is best to force the output low or at half supply.
APPLICATIO S I FOR ATIO
WUUU
TOTAL SUPPLY VOLTAGE (V)
0
SUPPLY CURRENT PER AMPLIFIER (µA)
5
4
3
2
1
04
1672/3/4 FO1
1235
OUTPUT V
S
/2
OUTPUT HIGH
OUTPUT LOW
Figure 1. Start-Up Characteristics
16/2/3/4 F02
OUTPUT HIGH
V
+
V
V
V
V
+
V
+
+
OUTPUT AT V
S
/2
+
OUTPUT LOW
+
820k
200k
Figure 2. Circuits for Start-Up Characteristics
Reverse Battery
The LT1672/LT1673/LT1674 are protected against reverse
battery voltages up to 18V. In the event a reverse battery
condition occurs, the supply current is typically less than
100nA (inputs grounded and outputs open). For typical
single supply applications with ground referred loads and
feedback networks, no other precautions are required. If
the reverse battery condition results in a negative voltage
at either the input pins or output pin, the current into the
pin should be limited by an external resistor to less than
10mA.
Inputs
While the LT1672/LT1673/LT1674 will function normally
with its inputs taken above the positive supply, the com-
mon mode range does not extend beyond approximately
300mV below the negative supply at room temperature.
Small-Signal Response Small-Signal Response Large-Signal Response
TYPICAL PERFORMANCE CHARACTERISTICS
UW
V
S
= ±15V
C
L
= 100pF
A
V
= 5
V
S
= 5V
C
L
= 100pF
A
V
= 5
V
S
= 5V
C
L
= 100pF
A
V
= 5
1672/3/4 G19 1672/3/4 G20 1672/3/4 G21
9
LT1672/LT1673/LT1674
and (VCC – 0.8V), Q1 and Q2 are active. When the input
common mode exceeds (VCC – 0.8V), Q7 turns on,
diverting the current from diff amp Q1-Q2 to current
mirror Q8-Q9. The current from Q8 biases on the other
diff amp consisting of PNP’s Q5-Q6 and NPN’s Q3-Q4.
Though Q5-Q6 are driven from the emitters rather than
the base, the basic diff amp action is the same. When the
common mode voltage is between (VCC – 0.8V) and VCC,
devices Q3 and Q4 act as followers, forming a buffer
between the amplifier inputs and the emitters of the Q5-
Q6. If the common mode voltage is taken above VCC,
Schottky diodes D1 and D2 reverse bias and devices Q3
and Q4 then act as diodes. The diff amp formed by Q5-Q6
operates normally, however, the input bias current in-
creases to the emitter current of Q5-Q6, which is typically
180nA. The graph, Input Bias Current vs Common Mode
Voltage found in the Typical Performance Characteristics
section, shows these transitions at three temperatures.
The collector currents of the two-input pairs are combined
in the second stage consisting of Q11 to Q16, which
furnishes most of the voltage gain. Capacitor C1 sets the
amplifier bandwidth. The output stage is configured for
maximum swing by the use of common emitter output
devices Q21 and Q22. Diodes D4 to D6 and current source
Q15 set the output quiescent current.
Figure 3. Simplified Schematic
1672/3/4 F03
Q6
Q4 Q16 Q17(V+) – 0.8V Q19
Q18 Q22
C1
D1 D2 D3
Q3
Q11
Q2 Q7
IN
IN+
Q10 Q13 Q20
Q21
OUT
Q12
Q14 Q15
Q5
Q8 R1 R2 I2
+I1
D6
D5
D4
D7
Q9
Q1
APPLICATIO S I FOR ATIO
WUUU
The device will not be damaged if the inputs are taken lower
than 300mV below the negative supply as long as the cur-
rent out of the pin is limited to less than 10mA. However,
the output phase is not guaranteed and the supply current
will increase.
Output
The graph, Capacitive Load Handling, shows amplifier sta-
bility with the output biased at half supply. If the output is
to be operated within about 100mV of the positive rail, the
allowable load capacitance is less. With this output volt-
age, the worst case occurs at AV = 5 and light loads, where
the load capacitance should be less than 500pF with a 5V
supply and less than 100pF with a 30V supply.
Rail-to-Rail Operation
The simplified schematic, Figure 3, details the circuit
design approach of the
LT1672/LT1673/LT1674
. The
amplifier topology is a three-stage design consisting of a
rail-to-rail input stage, that continues to operate with the
inputs above the positive rail, a folded cascode second
stage that develops most of the voltage gain, and a rail-to-
rail common emitter stage that provides the current gain.
The input stage is formed by two diff amps Q1-Q2 and Q3-
Q6. For signals with a common mode voltage between VEE
10
LT1672/LT1673/LT1674
Dimensions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
U
PACKAGE DESCRIPTIO
MS8 Package
8-Lead Plastic MSOP
(LTC DWG # 05-08-1660)
Battery Current Monitor
TYPICAL APPLICATIO S
U
N8 1098
0.100
(2.54)
BSC
0.065
(1.651)
TYP
0.045 – 0.065
(1.143 – 1.651)
0.130 ± 0.005
(3.302 ± 0.127)
0.020
(0.508)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.125
(3.175)
MIN 12 34
8765
0.255 ± 0.015*
(6.477 ± 0.381)
0.400*
(10.160)
MAX
0.009 – 0.015
(0.229 – 0.381)
0.300 – 0.325
(7.620 – 8.255)
0.325 +0.035
0.015
+0.889
0.381
8.255
()
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
Over-the-Top Comparator with Hysteresis
+
+
1672/3/4 TA04
R
SENSE
0.1
I
L
CHARGE
R
A
2N3904
V
O
= I
L
R
SENSE
FOR R
A
= 10k, R
B
= 100k (R
B
/R
A
5)
= 1V/A
CHARGE
OUT
DISCHARGE
OUT
DISCHARGE
2N3904
R
A
R
A
R
A
R
B
R
B
R
A
V
O
I
L
R
B
A1
1/2 LT1673
5V 12V
A2
1/2 LT1673
()
+
LT1672
IN1
(0V TO 12V)
IN2
(0V TO 12V)
2N5087
2N5210
1672/3/4 TA03
1M
V
OUT
1M
V
CC
100
1M
10k
HYSTERESIS =
10k
1M
5V (V
CC
)
I
S
< 10µA
MSOP (MS8) 1100
* 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
0.021 ± 0.006
(0.53 ± 0.015)
0° – 6° TYP
SEATING
PLANE
0.007
(0.18)
0.043
(1.10)
MAX
0.009 – 0.015
(0.22 – 0.38) 0.005 ± 0.002
(0.13 ± 0.05)
0.034
(0.86)
REF
0.0256
(0.65)
BSC 12
34
0.193 ± 0.006
(4.90 ± 0.15)
8765
0.118 ± 0.004*
(3.00 ± 0.102)
0.118 ± 0.004**
(3.00 ± 0.102)
11
LT1672/LT1673/LT1674
Dimensions in inches (millimeters) unless otherwise noted.
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.016 – 0.050
(0.406 – 1.270)
0.010 – 0.020
(0.254 – 0.508)× 45°
0°– 8° TYP
0.008 – 0.010
(0.203 – 0.254)
SO8 1298
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
TYP
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
1234
0.150 – 0.157**
(3.810 – 3.988)
8765
0.189 – 0.197*
(4.801 – 5.004)
0.228 – 0.244
(5.791 – 6.197)
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
*
**
U
PACKAGE DESCRIPTIO
S Package
14-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
1234
0.150 – 0.157**
(3.810 – 3.988)
14 13
0.337 – 0.344*
(8.560 – 8.738)
0.228 – 0.244
(5.791 – 6.197)
12 11 10 9
567
8
0.016 – 0.050
(0.406 – 1.270)
0.010 – 0.020
(0.254 – 0.508)× 45°
0° – 8° TYP
0.008 – 0.010
(0.203 – 0.254)
S14 1298
0.053 – 0.069
(1.346 – 1.752)
0.014 – 0.019
(0.355 – 0.483)
TYP
0.004 – 0.010
(0.101 – 0.254)
0.050
(1.270)
BSC
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
*
**
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 represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
12
LT1672/LT1673/LT1674
LINEAR TE CHNOLOGY CORPORATION 2001
167234f LT/TP 0101 4K • PRINTED IN USA
PART NUMBER DESCRIPTION COMMENTS
LTC®1440/41/42 Micropower Single/Dual Comparators with 1% Reference LTC1440: Single, LTC1441/42: Dual
LTC1443/LTC1444/LTC1445 Micropower Quad Comparators with 1% Reference LTC1443: 1.182 Reference
LTC1444/45: 1.221V Reference and Adjustable Hysteresis
LT1466/LT1467 75µA Dual/Quad Rail-to-Rail Input and Output Op Amps 390µV V
OS(MAX)
, Gain Bandwidth = 120kHz
LT1490A/LT1491A 50µA Dual/Quad Rail-to-Rail Input and Output Op Amps 950µV V
OS(MAX)
, Gain Bandwidth = 200kHz
LT1494/LT1495/LT1496 1.5µA Max Single/Dual/Quad Over-the-Top Unity Gain Stable Version of the LT1672/LT1673/LT1674
Precision Rail-to-Rail Input and Output Op Amps
LTC1540 Nanopower Single Comparator with 1% Reference 350nA Supply Current
LT1636 Single Over-the-Top Micropower, Rail-to-Rail 225µV V
OS(MAX)
, I
S
= 55µA (Max), Gain Bandwidth = 200kHz,
Input and Output Op Amp Shutdown Pin, MSOP
LT2078/LT2079 55µA Dual/Quad Single Supply Op Amps 120µV V
OS(MAX)
, Gain Bandwidth = 200kHz
LT2178/LT2179 17µA Dual/Quad Single Supply Op Amps 120µV V
OS(MAX)
, Gain Bandwidth = 60kHz
LT1782 Micropower, Over-The-Top, SOT-23, Rail-to-Rail SOT-23, 800µV V
OS(MAX)
, I
S
= 55µA (Max),
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
S
= 300µA (Max),
Input and Output Op Amp in SOT-23 Gain-Bandwidth = 1.2MHz, Shutdown Pin
RELATED PARTS
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
FAX: (408) 434-0507
www.linear-tech.com
U
TYPICAL APPLICATIO
+
1672/3/4 TA05
CD
170pF
LT1672
VS+
VS
R1
10M
C1
20pF
VOUT
880nm IR
PHOTODIODE
OPTO-DIODE CORP
ODD-45W
λ
IPHOTODIODE
GAIN: AZ = 10M =
10% TO 90% RISE TIME: tr = 260µs
BANDWIDTH: BW = 1.7kHz
IPHOTODIODE
VOUT
VS = ±1.2V TO ±15V
C1, CD SATISFY GAIN OF 5
STABILITY REQUIREMENT AT AC.
Micropower Photodiode Amplifier