LTC6252 Linear Technology, LTC6252 Datasheet - Page 18

• Manufacturer Part Number: LTC6252
• Description: 3.5mA Power Efficient Rail-to-Rail I/O Op Amps
• Manufacturer: Linear Technology

DataSheet.in
LTC6252/LTC6253/LTC6254
TYPICAL APPLICATIONS
See the oscillograph of Figure 7, showing the inputs V
and V
Note that there are protection diodes across the op amp
inputs, so large signals at the output will feed back into the
upstream off channel through the diodes. R1 and R2 were
put in place to reduce the loading on the output, as well
as to reduce the upstream feedback current and improve
reverse isolation. Some reverse crosstalk can be discerned
in the V
however, as the reverse current works back into the 50Ω
source impedance of the function generators.
High Speed Low Voltage Instrumentation Amplifi er
Figure 8 shows a three op amp instrumentation amplifi er
with a gain of 41V/V which can operate on low supplies.
Op amps U1 and U2 are channels from an LTC6253.
Op amp U3 can be an LTC6252 or one channel of an
LTC6253. Figure 9 shows the measured frequency re-
sponse of the instrumentation amplifi er for a load of 1kΩ.
Figure 10 shows the measured CMRR of the instrumenta-
tion amplifi er, and Figure 11 shows the transient response
for a 50mV
input, with the negative input grounded.
18
40
35
30
25
20
15
10
5
0
10k
B
Figure 9. Instrumentation Amplifi er
Frequency Response
, the SEL_B control, and the resulting output.
A
and V
P-P
100k
input square wave applied to the positive
B
FREQUENCY (Hz)
traces during their respective off times,
1M
10M
625234 F09
100M
120
100
80
60
40
20
0
10k
Figure 10. Instrumentation
Amplifi er CMRR
100k
A
FREQUENCY (Hz)
1M
Figure 8. High Speed Low Voltage Instrumentation Amplifi er
5V/DIV
IN
IN
+
–
10M
R1
60Ω
Figure 7. Oscilloscope Traces Showing
Multiplexing Channels
+
½ LTC6253
–
–
½ LTC6253
+
625234 F10
V
V
U1
U2
S
S
100M
+
–
1.2k
1.2k
R2
R3
25mV/DIV
OUTPUT
A
BW = 15MHz
V
1V/DIV
INPUT
V
S
= 41
= ±1.5V
0V
0V
50μs/DIV
750Ω
750Ω
R4
R5
Figure 11. Transient Response,
Instrumentation Amplifi er
I
S
½ LTC6253
+
–
= 8.4mA
750Ω
V
V
U3
R6
S
S
+
–
100ns/DIV
750Ω
R7
625234 F07
625234 F08
SEL_B
V
V
V
OUT
A
B
V
OUT
625234 F11
625234f