OPA541 Datasheet, PDF (7/8 Pages) Burr-Brown (TI) – High Power Monolithic OPERATIONAL AMPLIFIER

SAFE OPERATING AREA
10
T_C = +25°C
T_C = +85°C
T_C = +125°C
1
“M” Package only
0.1
1
AP, AM
BM, SM
10
100
|V_S – V_OUT | (V)
FIGURE 1. Safe Operating Area.
Short circuit protection requires evaluation of SOA. When
the amplifier output is shorted to ground, the full power
supply voltage is impressed across the conducting output
transistor. The current limit must be set to a value which is
safe for the power supply voltage used. For instance, with V_S
±35V, a short to ground would force 35V across the conduc-
ting power transistor. A current limit of 1.8A would be safe.
Reactive, or EMF-generating, loads such as DC motors can
present difficult SOA requirements. With a purely reactive
load, output voltage and load current are 90° out of phase.
Thus, peak output current occurs when the output voltage is
zero and the voltage across the conducting transistor is equal
to the full power supply voltage. See Burr-Brown Applica-
tion Bulletin AB-039 for further information on evaluating
SOA.
REPLACING HYBRID POWER AMPLIFIERS
The OPA541 can be used in applications currently using
various hybrid power amplifiers, including the OPA501,
OPA511, OPA512, and 3573. Of course, the application
must be evaluated to assure that the output capability and
other performance attributes of the OPA541 meet the neces-
sary requirement. These hybrid power amplifiers use two
current limit resistors to independently set the positive and
negative current limit value. Since the OPA541 uses only
one current limit resistor to set both the positive and negative
current limit, only one resistor (see Figure 4) need be
installed. If installed, the resistor connected to pin 2 (TO-3
package) is superfluous, but it does no harm.
Because one resistor carries the current previously carried
by two, the resistor may require a higher power rating.
Minor adjustments may be required in the resistor value to
achieve the same current limit value. Often, however, the
change in current limit value when changing models is small
compared to its variation over temperature. Many applica-
tions can use the same current limit resistor.
APPLICATIONS CIRCUITS
+V_S
10µF
0.1µF
D₁
OPA541
0.1µF
10µF
–V_S
Inductive or
D₂
L EMF-Generating
Load
D₁ – D₂ : IN4003
FIGURE 2. Clamping Output for EMF-Generating Loads.
R₁
10kΩ
V_IN
R₂
20pF _100kΩ
OPA541
Master
0.1Ω
10kΩ
OPA541
Slave
20pF
0.1Ω
A _V = –R₂ /R₁
= –10
L
FIGURE 3. Isolating Capacitive Loads.
R_CL+
2
OPA501
8
1
R_CL–
Not Required
2
1
OPA541
8
R_CL
Pin 2 is “open” on OPA541.
FIGURE 4. Replacing OPA501 with OPA541.
®
7
OPA541