TSH80I ST Microelectronics, Inc., TSH80I Datasheet - Page 15

• Manufacturer Part Number: TSH80I
• Description: Wide Band Rail to Rail Operational Amplifier With Standby Function
• Manufacturer: ST Microelectronics, Inc.

Video Results:
Precautions on asymmetrical supply
operation:
The TSH8X can be used either with a dual or a
single supply. If a single supply is used, the inputs
are biased to the mid-supply voltage (+Vcc/2).
This bias network must be carefully designed, in
order to reject any noise present on the supply rail.
As the bias current is 15uA, you must carefully
choose the resistance R1 not to introduce an off-
set mismatch at the amplifier inputs.
R1=10k
pass capacitors from perturbation on Vcc as well
as for the input and output signals. We choose
C1=100nF and C2=C3=100uF.
IN
Diff Phase Step1
Diff Phase Step2
Diff Phase Step3
Diff Phase Step4
Diff Phase Step5
Cin
Diff Gain Step1
Diff Gain Step2
Diff Gain Step3
Diff Gain Step4
Diff Gain Step5
R1
Lum NL Step 1
Lum NL Step 2
Lum NL Step 3
Lum NL Step 4
Lum NL Step 5
Diff Phase pos
Diff Phase neg
Diff Phase pp
Diff Gain neg
Diff Gain pos
Diff Gain pp
Parameter
Lum NL
will be convenient. C1, C2, C3 are by-
R2
R3 C1
Vcc+
C2
C3
R4
+
-
R5
Cf
Value (Vcc= 2.5V)
Cout
99.9
99.9
99.9
100
100
-0.7
-0.5
-0.7
-0.3
-0.1
-0.4
-0.2
-0.2
-0.1
-0.1
-0.2
0.1
0.7
0.2
OUT
0
0
0
RL
R2, R3 are such that the current through them
must be superior to 100 times the bias current. So,
we take R2=R3=4.7k .
Cin, as Cout are chosen to filter the DC signal by
the low pass filters (R1,Cin) and (Rout, Cout). By
taking
Cout=220uF we provide a cutoff frequency below
10Hz.
Use of the TSH8X in gain=-1 configuration:
Some precautions have to be added, specially for
low power supply application.
A feedback capacitance Cf should be added for
better stability. The table summarizes the impact
of the capacitance Cf on the phase margin of the
circuit.
IN
Cin
R1
R1=10k ,
R2
R3 C1
Value (Vcc= 5V)
Vcc+
1k
C2
99.9
99.8
99.9
99.7
100
-0.6
-0.3
-0.6
-0.5
-0.3
-0.5
-0.4
-0.4
-0.4
-0.3
-0.1
0.3
0.6
0.1
0.5
0.1
RL=150
C3
0
TSH80-TSH81-TSH82
1k
Cf
+
-
and
Cout
Cin=2uF,
OUT
Unit
deg
deg
deg
deg
deg
deg
deg
deg
%
%
%
%
%
%
%
%
%
%
%
%
%
%
RL
15/18