LT1189CS8#TR Linear Technology, LT1189CS8#TR Datasheet - Page 9

• Manufacturer Part Number: LT1189CS8#TR
• Description: IC AMP VID DIFF CURR FDBK 8SOIC
• Manufacturer: Linear Technology

Specifications of LT1189CS8#TR

• Applications: Differential
• Number Of Circuits: 1
• -3db Bandwidth: 35MHz
• Slew Rate: 220 V/µs
• Current - Supply: 13mA
• Current - Output / Channel: 20mA
• Voltage - Supply, Single/dual (±): 4.75 V ~ 16 V, ±2.38 V ~ 8 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

A
Instrumentation Amplifier Rejects High Voltage
Instrumentation amplifiers are often used to process
slowly varying outputs from transducers. With the LT1189
it is easy to make an instrumentation amplifier that can
respond to rapidly varying signals. Attenuation resistors
in front of the LT1189 allow very large common-mode
signals to be rejected while maintaining good frequency
response. The input common-mode and differential-mode
signals are reduced by 100:1, while the closed-loop gain
is set to be 100, thereby maintaining unity-gain input to
output. The unique topology allows for frequency re-
sponse boost by adding 150pF to pin 8 as shown.
* 0.1% RESISTORS
PPLICATI
Output of Instrumentation Amplifier with 1MHz Square Wave
WORST CASE CMRR = 48dB
120V
3.5MHz Instrumentation Amplifier Rejects 120V
V
V
P-P
CM
IN
Riding on 120V
O
10k*
10k*
U
S
100*
100*
I FOR ATIO
150pF
U
P-P
at the Input
100
2
1
3
8
W
REF
–
FB
+
10k
LT1189
–5V
5V
7
4
LT1189 • AI04
LT1189 • AI03
6
U
P-P
Operating with Low Closed-Loop Gain
The LT1189 has been optimized for closed-loop gains of
10 or greater. The amplifier can be operated at much lower
closed-loop gains with the aid of a capacitor C
the feedback resistor, (feedback zero). This capacitor
lowers the closed-loop 3dB bandwidth. The bandwidth
cannot be made arbitrarily low because C
high frequency and the amplifier will appear configured
unity-gain. As an approximate guideline, make BW A
= 200MHz. This expression expands to:
or:
The effect of the feedback zero on the transient and
frequency response is shown for A
C
2
FB
High Voltage Instrumentation Amplifier Response
R
A
FB
VCL
–20
–40
– 60
200
20
0
C
100k
FB
MHz
DIFFERENTIAL-MODE RESPONSE
A
VCL
200
2
1M
FREQUENCY (Hz)
COMMON-MODE RESPONSE
MHz
R
FB
10M
V
= 4.
LT1189 • AI05
FB
100M
is a short at
LT1189
FB
across
9
VCL