OPA454 Datasheet, PDF (16/36 Pages) Texas Instruments – High-Voltage (100V), High-Current (50mA) OPERATIONAL AMPLIFIERS, G = 1 Stable

OPA454
SBOS391 – DECEMBER 2007
www.ti.com
APPLICATIONS INFORMATION
Figure 57 shows the OPA454 connected as a basic
noninverting amplifier. The OPA454 can be used in
virtually any ±5V to ±50V op amp configuration. It is
especially useful for supply voltages greater than
36V.
Power-supply terminals should be bypassed with
0.1µF (or greater) capacitors, located near the
power-supply pins. Be sure that the capacitors are
appropriately rated for the power-supply voltage
used.
V+
0.1mF
I_P
V+
R₁
R_P(1)
R₂
G
=
1+
R₂
R₁
POWER SUPPLIES
The OPA454 may be operated from power supplies
up to ±50V or a total of 100V with excellent
performance. Most behavior remains unchanged
throughout the full operating voltage range.
Parameters that vary significantly with operating
voltage are shown in the Typical Characteristics.
Some applications do not require equal positive and
negative output voltage swing. Power-supply voltages
do not need to be equal. The OPA454 can operate
with as little as 10V between the supplies and with up
to 100V between the supplies. For example, the
positive supply could be set to 90V with the negative
supply at –10V, or vice-versa (as long as the total is
less than or equal to 100V).
INPUT PROTECTION
V+
-IN
Status
Flag
V_OUT
OPA454
+IN
E/D
V_IN
E/D Com
V-
0.1mF
V_OUT
R_L
V-
V-
(1) Pull-up resistor with at least 10µA (choose
R_P = 1MΩ with V+ = 50V for I_P = 50µA).
Figure 57. Basic Noninverting Amplifier
Configuration
The OPA454 has increased protection against
damage caused by excessive voltage between op
amp input pins or input pin voltages that exceed the
power supplies; external series resistance is not
needed for protection. Internal series JFETs limit
input overload current to a non-destructive 4mA, even
with an input differential voltage as large as 120V.
Additionally, the OPA454 has dielectric isolation
between devices and the substrate. Therefore, the
amplifier is free from the limitations of junction
isolation common to many IC fabrication processes.
LOWERING OFFSET VOLTAGE AND DRIFT
The OPA454 can be used with an OPA735 zero-drift
series op amp to create a high-voltage op amp circuit
that has very low input offset temperature drift. This
circuit is shown in Figure 58.
Low Offset, 5mV, Drift,
0.05mV/°C, Self-Zeroing Op Amp
Gain 1st = 4.9V/V
R₁, 1st
10kW
R₂, 1st
39.1kW
High-Voltage Op Amp
Gain 2nd = 9.45V/V
R₁, 2nd
10kW
R₂, 2nd
84.5kW
V_G = ±1V
V+
1st Stage, +5V
V_OUT 1st Stage
OPA735
A₁, 1st Stage
V-
1st Stage, -5V
V_OUT 1st Stage ±4.9V, Max
V+
2nd Stage, +50V
V_OUT 2nd Stage
OPA454
A₂, 2nd Stage
R_LOAD
10kW
V-
2nd Stage, -50V
V_OUT 2nd Stage ±46V (92V_PP), Max
V_INPUT = ±1V_PP
Figure 58. Two-Stage, High-Voltage Op Amp Circuit With Very Low Input Offset Temperature Drift
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