OPA452 Datasheet, PDF (9/17 Pages) Texas Instruments – 80V, 50mA OPERATIONAL AMPLIFIERS

APPLICATIONS INFORMATION
Figure 1 shows the OPA452 connected as a basic noninverting
amplifier. The OPA452 can be used in virtually any op amp
configuration. The OPA453 is designed for use in configura-
tions with gains of 5 or greater. Power-supply terminals
should be bypassed with 0.1µF capacitors, or greater, near
the power-supply pins. Be sure that the capacitors are
appropriately rated for the power-supply voltage used. The
OPA452 and OPA453 can supply output currents up to
50mA with excellent performance.
V+
10µF
+
0.1µF
G = 1+
R₂
R₁
R₁
R₂
OPA452
V_O
V_IN
Flag
Z_L
(optional)
0.1µF
10µF
+
V–
FIGURE 1. Basic Circuit Connections.
CURRENT LIMIT
The OPA452 and OPA453 are designed with internal cur-
rent-limiting circuitry that limits the output current to approxi-
mately 125mA. The current limit varies slightly with increas-
ing junction temperature and supply voltage, as shown in the
Typical Characteristics. Current limit, in combination with the
thermal protection circuitry, provides protection from most
types of overload conditions including short-circuit to ground.
THERMAL PROTECTION
The OPA452 and OPA453 have thermal shutdown circuitry
that protects the amplifier from damage caused by overload
conditions. The thermal protection circuitry disables the out-
put when the junction temperature reaches approximately
160°C, allowing the device to cool. When the junction tem-
perature cools to approximately 140°C, the output circuitry is
automatically re-enabled.
The thermal shutdown function is not intended to replace
proper heat sinking. Activation of the thermal shutdown
circuitry is an indication of excessive power dissipation or an
inadequate heat sink. Continuously running the amplifier into
thermal shutdown can degrade reliability.
The Thermal Shutdown Indicator (Flag) pin can be monitored
to determine if shutdown is occurring. During normal opera-
tion, the current output from the flag pin is typically 50nA.
During shutdown, the current output from the flag pin in-
creases to 140µA (typical). This current output allows for
easy interfacing to external logic. Figure 2 shows two ex-
amples implementing this function.
OPA452
V_OUT
HCT logic has relatively well-
controlled logic level. A properly
chosen resistor value can
assure proper logic high level
throughout the full range of flag
output current.
Flag
100µA to _+5V
165µA
HCT
19.1kΩ
Logic
Ground
Interfacing with HCT Logic
FIGURE 2. Thermal Shutdown Indicator.
OPA452
V_OUT
+5V
Interface to virtually any CMOS
logic gate by choosing a resistor
value that provides an assured
logic high voltage with the
minimum (100µA) flag current.
39kΩ
CMOS
Logic
Ground
Interfacing with CMOS Logic
OPA452, 453
9
SBOS127C
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