LT1167CS8#TR Linear Technology, LT1167CS8#TR Datasheet - Page 14

• Manufacturer Part Number: LT1167CS8#TR
• Description: IC AMP INSTR PROG PREC LP 8SOIC
• Manufacturer: Linear Technology

Specifications of LT1167CS8#TR

• Amplifier Type: Instrumentation
• Number Of Circuits: 1
• Slew Rate: 1.2 V/µs
• Gain Bandwidth Product: 1MHz
• Current - Input Bias: 80pA
• Voltage - Input Offset: 20µV
• Current - Supply: 900µA
• Current - Output / Channel: 27mA
• Voltage - Supply, Single/dual (±): 4.6 V ~ 36 V, ±2.3 V ~ 18 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Output Type: -
• -3db Bandwidth: -

LT1167
Theory oF operaTion
applicaTions inForMaTion
The LT1167 is a low power precision instrumentation
amplifier that requires only one external resistor to accu-
rately set the gain anywhere from 1 to 1000. The output
can handle capacitive loads up to 1000pF in any gain
configuration and the inputs are protected against ESD
strikes up to 13kV (human body).
Input Current at High Common Mode Voltage
When operating within the specified input common mode
range, both the LT1167 and LT1167-1 operate as shown
in the Input Bias Current vs Common Mode Input Voltage
graph shown in the Typical Performance Characteristics.
If however the inputs are within approximately 0.8V of
the positive supply, the LT1167 input current will increase
to approximately –1µA to –3µA. If the impedance of the
circuit driving the LT1167 inputs is sufficiently high (e.g.,
10MΩ when +V
pull the input voltage sufficiently high to keep the elevated
input current flowing. The LT1167-1 has been modified so
that the input current is typically two orders of magnitude
lower under similar conditions. The LT1167-1 is recom-
mended for new designs where input impedance is high.
Input Protection
The LT1167 can safely handle up to ± 20mA of input cur-
rent in an overload condition. Adding an external 5k input
resistor in series with each input allows DC input fault
voltages up to ±100V and improves the ESD immunity
to 8kV (contact) and 15kV (air discharge), which is the
IEC 1000-4-2 level 4 specification. If lower value input
14
THERMOCOUPLE
10k
R
S
G
= 15V), this increased input current can
–
+
LT1167
Figure 3. Providing an Input Common Mode Current Path
HYDROPHONE,
MICROPHONE,
ETC
200k
200k
R
G
resistors are needed, a clamp diode from the positive supply
to each input will maintain the IEC 1000-4-2 specification
to level 4 for both air and contact discharge. A 2N4393
drain/source to gate is a good low leakage diode for use
with 1k resistors, see Figure 4. The input resistors should
be carbon and not metal film or carbon film.
RFI Reduction
In many industrial and data acquisition applications,
instrumentation amplifiers are used to accurately amplify
small signals in the presence of large common mode volt-
ages or high levels of noise. Typically, the sources of these
very small signals (on the order of microvolts or millivolts)
are sensors that can be a significant distance from the
signal conditioning circuit. Although these sensors may be
connected to signal conditioning circuitry, using shielded
or unshielded twisted-pair cabling, the cabling may act
as antennae, conveying very high frequency interference
directly into the input stage of the LT1167.
–
+
LT1167
R
R
IN
IN
V
CC
J1
2N4393
Figure 4. Input Protection
V
CC
J2
2N4393
BIAS CURRENT RETURN
CENTER-TAP PROVIDES
R
G
OPTIONAL FOR HIGHEST
ESD PROTECTION
R
+
–
G
–
+
LT1167
V
V
CC
EE
LT1167
REF
OUT
1167 F04
1167 F03
1167fb