OPA192 Datasheet, PDF (19/35 Pages) Texas Instruments – High Voltage, Rail-to-Rail Input/Output, Precision Operational Amplifiers, e-trim Series

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OPA192
OPA2192
OPA4192
SBOS620A – DECEMBER 2013 – REVISED JANUARY 2014
INPUT PROTECTION CIRCUITRY
The OPA192 uses a unique input architecture to eliminate the need for input protection diodes but still provides
robust input protection under transient conditions. Conventional input diode protection schemes shown in
Figure 45 can be activated by fast transient step responses and can introduce signal distortion and settling time
delays due to alternate current paths, as shown in Figure 46. For low-gain circuits, these fast-ramping input
signals forward-bias back-to-back diodes causing an increase in input current and resulting in extended settling
time, as seen in Figure 47.
V+
V+
VIN+
36 V
OPA192
VOUT
VIN+
~0.7 V
VOUT
VIN
OPA192 Provides Full 36-V
Differential Input Range
VIN
Conventional Input Protection
Limits Differential Input Range
V
V
Figure 45. OPA192 Input Protection Does Not Limit Differential Input Capability
V_n=+10V ^RFILT +10V _Sn
R_{on_mux}
1
C_FILT
C_S
V_n+1=-
10V
R_FILT
-10V
S_n+
1
C_FILT
C_S
R_{on_mux}
2
I_{diode_transient}
D
C_D
1
+10V
Vin-
~0.7V
-10V^Vin+
2
~-9.3V
Vout
Input Low Pass Filter
Simplified Mux Model
Buffer Amplifier
Figure 46. Back-to-Back Diodes Create Settling Issues
100
80
60
40
20
0
±20
±40
±60
±80
±100
0
Standard Input Diode Structure
Extends Settling Time
0.1% Settling = ±10 mV
OPA192 Input Structure
Offers Fast Settling
5 10 15 20 25 30 35 40 45 50 55 60
Time (s)
C040
Figure 47. OPA192 Protection Circuit Maintains Fast-Settling Transient Response
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Product Folder Links: OPA192 OPA2192 OPA4192