1
OPA541
OPA541
DESCRIPTION
The OPA541 is a power operational amplifier capable
of operation from power supplies up to
40V and
delivering continuous output currents up to 5A. Inter-
nal current limit circuitry can be user-programmed
with a single external resistor, protecting the amplifier
and load from fault conditions. The OPA541 is fabri-
cated using a proprietary bipolar/FET process.
Pinout is compatible with popular hybrid power am-
plifiers such as the OPA511, OPA512 and the 3573.
High Power Monolithic
OPERATIONAL AMPLIFIER
APPLICATIONS
q
MOTOR DRIVER
q
SERVO AMPLIFIER
q
SYNCHRO EXCITATION
q
AUDIO AMPLIFIER
q
PROGRAMMABLE POWER SUPPLY
FEATURES
q
POWER SUPPLIES TO
40V
q
OUTPUT CURRENT TO 10A PEAK
q
PROGRAMMABLE CURRENT LIMIT
q
INDUSTRY-STANDARD PIN OUT
q
FET INPUT
q
TO-3 AND LOW-COST POWER PLASTIC
PACKAGES
The OPA541 uses a single current-limit resistor to set
both the positive and negative current limits. Applica-
tions currently using hybrid power amplifiers requir-
ing two current-limit resistors need not be modified.
The OPA541 is available in an 11-pin power plastic
package and an industry-standard 8-pin TO-3 her-
metic package. The power plastic package has a cop-
per-lead frame to maximize heat transfer. The TO-3
package is isolated from all circuitry, allowing it to be
mounted directly to a heat sink without special insula-
tors.
Current
Sense
Output
Drive
R
CL
+In
In
External
+V
S
V
S
V
O
PDS-737H
International Airport Industrial Park Mailing Address: PO Box 11400, Tucson, AZ 85734 Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 Tel: (520) 746-1111 Twx: 910-952-1111
Internet: http://www.burr-brown.com/ FAXLine: (800) 548-6133 (US/Canada Only) Cable: BBRCORP Telex: 066-6491 FAX: (520) 889-1510 Immediate Product Info: (800) 548-6132
2
OPA541
SPECIFICATIONS
ELECTRICAL
At T
C
= +25
C and V
S
=
35VDC, unless otherwise noted.
OPA541AM/AP
OPA541BM/SM
PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
INPUT OFFSET VOLTAGE
V
OS
2
10
0.1
1
mV
vs Temperature
Specified Temperature Range
20
40
15
30
V/
C
vs Supply Voltage
V
S
=
10V to
V
MAX
2.5
10
T
T
V/V
vs Power
20
60
T
T
V/W
INPUT BIAS CURRENT
I
B
4
50
T
T
pA
INPUT OFFSET CURRENT
I
OS
1
30
T
T
pA
Specified Temperature Range
5
T
nA
INPUT CHARACTERISTICS
Common-Mode Voltage Range
Specified Temperature Range
(|V
S
| 6)
(|V
S
| 3)
T
T
V
Common-Mode Rejection
V
CM
= (|
V
S
| 6V)
95
113
T
T
dB
Input Capacitance
5
T
pF
Input Impedance, DC
1
T
T
GAIN CHARACTERISTICS
Open Loop Gain at 10Hz
R
L
= 6
90
97
T
T
dB
Gain-Bandwidth Product
1.6
T
MHz
OUTPUT
Voltage Swing
I
O
= 5A, Continuous
(|V
S
| 5.5)
(|V
S
| 4.5)
T
T
V
I
O
= 2A
(|V
S
| 4.5)
(|V
S
| 3.6)
T
T
V
I
O
= 0.5A
(|V
S
| 4)
(|V
S
| 3.2)
T
T
V
Current, Peak
9
10
T
T
A
AC PERFORMANCE
Slew Rate
6
10
T
T
V/
s
Power Bandwidth
R
L
= 8
, V
O
= 20Vrms
45
55
T
T
kHz
Settling Time to 0.1%
2V Step
2
T
s
Capacitive Load
Specified Temperature Range, G = 1
3.3
T
nF
Specified Temperature Range, G >10
SOA
(1)
T
Phase Margin
Specified Temperature Range, R
L
= 8
40
T
Degrees
POWER SUPPLY
Power Supply Voltage,
V
S
Specified Temperature Range
10
30
35
T
35
40
V
Current, Quiescent
20
25
T
T
mA
THERMAL RESISTANCE
JC
(Junction-to-Case)
(2)
AC Output f > 60Hz
2.5
C/W
JC
(2)
DC Output
3
C/W
JA
(Junction-to-Ambient)
No Heat Sink
40
C/W
OPA541AP (Plastic)
40
C/W
TEMPERATURE RANGE
T
CASE
AM, BM, AP
25
+85
T
T
C
SM
55
+125
C
T
Specification same as OPA541AM/AP.
NOTE: (1) SOA is the Safe Operating Area shown in Figure 1. (2) Plastic package may require insulator which typically adds 1
C/W.
The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user's own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.
3
OPA541
Top View
TO3
Plastic Package
CONNECTION DIAGRAMS
In
NC
+In
NC
V
O
Output
Drive
R
CL
V
S
+V
S
Current
Sense
1
3
5
7
9
11
2
4
6
8
10
Tab at V
S
Current
Sense
V
S
+In
In
+V
S
NC
NC
Output
Drive
R
CL
V
O
1
2
3
8
5
6
4
7
ORDERING INFORMATION
TEMPERATURE
CONTINUOUS
PRODUCT
PACKAGE
RANGE
CURRENT
OPA541AP
Power Plastic
25
C to +85
C
5A at 25
C
OPA541AM
TO-3
25
C to +85
C
5A at 25
C
OPA541BM
TO-3
25
C to +85
C
5A at 25
C
OPA541SM
TO-3
55
C to +125
C
5A at 25
C
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, +V
S
to V
S
............................................................... 80V
Output Current ............................................................................. see SOA
Power Dissipation, Internal
(1)
........................................................... 125W
Input Voltage: Differential ....................................................................
V
S
Common-mode .............................................................
V
S
Temperature: Pin solder, 10s ........................................................ +300
C
Junction
(1)
............................................................... +150
C
Temperature Range:
AM, BM SM
Storage .................................................................... 65
C to +150
C
Operating (case) ...................................................... 55
C to +125
C
AP
Storage ...................................................................... 40
C to +85
C
Operating (case) ........................................................ 25
C to +85
C
NOTE: (1) Long term operation at the maximum junction temperature will
result in reduced product life. Derate internal power dissipation to achieve
high MTTF.
PACKAGE INFORMATION
PACKAGE DRAWING
PRODUCT
PACKAGE
NUMBER
(1)
OPA541AP
Power Plastic
242
OPA541AM
TO-3
030
OPA541BM
TO-3
030
OPA541SM
TO-3
030
NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.
ELECTROSTATIC
DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling
and installation procedures can cause damage.
ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.
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OPA541
10
1
0.1
0.01
0.001
10
100
1k
10k
100k
Frequency (Hz)
THD + Noise (%)
TOTAL HARMONIC DISTORTION + NOISE
vs FREQUENCY
P = 100mW
O
P = 50W
O
A = 5
V
P = 5W
O
1k
100
10
Voltage Noise Density (nV/
Hz)
VOLTAGE NOISE DENSITY
vs FREQUENCY
1
10
100
1k
10k
100k
Frequency (Hz)
6
5
4
3
2
1
0
0
1
2
3
4
5
6
7
8
9
10
I (A)
OUT
|V | |V | (V)
OUT
S
OUTPUT VOLTAGE SWING
vs OUTPUT CURRENT
|V | |V |
S
O
(+V ) V
S
O
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
20
30
40
50
60
70
80
90
+V + |V | (V)
S
S
Normalized I
NORMALIZED QUIESCENT CURRENT
vs TOTAL POWER SUPPLY VOLTAGE
T = +25C
C
T = 25C
C
T = +125C
C
Q
110
90
70
50
30
10
10
1
10
100
1k
10k
100k
1M
10M
Frequency (Hz)
Voltage Gain (dB)
OPEN-LOOP GAIN AND PHASE
vs FREQUENCY
0
45
90
135
180
Phase (Degrees)
Phase
Gain
Z = 3.3nF
L
Z = 3.3nF
L
Z = 2k
L
Z = 2k
L
25
0
25
50
75
100
125
100
10
1
0.1
0.01
0.001
Input Bias Current (nA)
Temperature (C)
INPUT BIAS CURRENT
vs TEMPERATURE
TYPICAL PERFORMANCE CURVES
At T
A
= +25
C, V
S
=
35VDC, unless otherwise noted.
5
OPA541
120
110
100
90
80
70
60
50
10
100
1k
10k
100k
1M
Frequency (Hz)
CMRR (dB)
COMMON-MODE REJECTION
vs FREQUENCY
10
1
0.1
0.01
0.1
1
10
R ( )
CL
I (A)
LIMIT
CURRENT LIMIT
vs RESISTANCE LIMIT
TO-3
Power Plastic
NOTE: These are averaged values.
I is typically 10% higher.
+I is typically 10% lower.
OUT
OUT
TYPICAL PERFORMANCE CURVES
(CONT)
At T
A
= +25
C, V
S
=
35VDC, unless otherwise noted.
Time (1s/division)
DYNAMIC RESPONSE
Voltage (2V/division)
10
1
0.1
0.01
0.1
1
10
R ( )
CL
I (A)
LIMIT
CURRENT LIMIT vs RESISTANCE LIMIT
vs TEMPERATURE
Power Plastic at 25C
Power Plastic at +85C
NOTE: These are averaged values.
I is typically 10% higher.
+I is typically 10% lower.
OUT
OUT
TO-3 at 25C
TO-3 at +85C
6
OPA541
HS
=
T
CASE
T
AMBIENT
P
D
(max)
INSTALLATION
INSTRUCTIONS
POWER SUPPLIES
The OPA541 is specified for operation from power supplies
up to
40V. It can also be operated from unbalanced power
supplies or a single power supply, as long as the total power
supply voltage does not exceed 80V. The power supplies
should be bypassed with low series impedance capacitors
such as ceramic or tantalum. These should be located as near
as practical to the amplifier's power supply pins. Good
power amplifier circuit layout is, in general, like good high
frequency layout. Consider the path of large power supply
and output currents. Avoid routing these connections near
low-level input circuitry to avoid waveform distortion and
oscillations.
CURRENT LIMIT
Internal current limit circuitry is controlled by a single
external resistor, R
CL
. Output load current flows through this
external resistor. The current limit is activated when the
voltage across this resistor is approximately a base-emitter
turn-on voltage. The value of the current limit resistor is
approximately:
(AM, BM, SM)
R
CL
=
0.057
(AP)
R
CL
=
0.02
0.809
| I
LIM
|
0.813
| I
LIM
|
Because of the internal structure of the OPA541, the actual
current limit depends on whether current is positive or
negative. The above R
CL
gives an average value. For a given
R
CL
, +I
OUT
will actually be limited at about 10% below the
expected level, while I
OUT
will be limited about 10% above
the expected level.
The current limit value decreases with increasing tempera-
ture due to the temperature coefficient of a base-emitter
junction voltage. Similarly, the current limit value increases
at low temperatures. Current limit versus resistor value and
temperature effects are shown in the Typical Performance
Curves. Approximate values for R
CL
at other temperatures
may be calculated by adjusting R
CL
as follows:
The adjustable current limit can be set to provide protection
from short circuits. The safe short-circuit current depends on
power supply voltage. See the discussion on Safe Operating
Area to determine the proper current limit value.
Since the full load current flows through R
CL
, it must be
selected for sufficient power dissipation. For a 5A current
limit on the TO-3 package, the formula yields an R
CL
of
0.105
(0.143
on the power plastic package due to differ-
ent internal resistances). A continuous 5A through 0.105
would require an R
CL
that can dissipate 2.625W.
R
CL
=
x
(T 25)
2mV
| I
LIM
|
Sinusoidal outputs create dissipation according to rms load
current. For the same R
CL
, AC peaks would still be limited
to 5A, but rms current would be 3.5A, and a current limiting
resistor with a lower power rating could be used. Some
applications (such as voice amplification) are assured of
signals with much lower duty cycles, allowing a current
resistor with a low power rating. Wire-wound resistors may
be used for R
CL
. Some wire-wound resistors, however, have
excessive inductance and may cause loop-stability prob-
lems. Be sure to evaluate circuit performance with resistor
type planned for production to assure proper circuit opera-
tion.
HEAT SINKING
Power amplifiers are rated by case temperature, not ambient
temperature as with signal op amps. Sufficient heat sinking
must be provided to keep the case temperature within rated
limits for the maximum ambient temperature and power
dissipation. The thermal resistance of the heat sink required
may be calculated by:
Commercially available heat sinks often specify their ther-
mal resistance. These ratings are often suspect, however,
since they depend greatly on the mounting environment and
air flow conditions. Actual thermal performance should be
verified by measurement of case temperature under the
required load and environmental conditions.
No insulating hardware is required when using the TO-3
package. Since mica and other similar insulators typically
add approximately 0.7
C/W thermal resistance, their elimi-
nation significantly improves thermal performance. See Burr-
Brown Application Bulletin AB-038 for further details on
heat sinking. On the power plastic package, the metal tab is
connected to V
S
, and appropriate actions should be taken
when mounting on a heat sink or chassis.
SAFE OPERATING AREA
The safe operating area (SOA) plot provides comprehensive
information on the power handling abilities of the OPA541.
It shows the allowable output current as a function of the
voltage across the conducting output transistor (see Figure
1). This voltage is equal to the power supply voltage minus
the output voltage. For example, as the amplifier output
swings near the positive power supply voltage, the voltage
across the output transistor decreases and the device can
safely provide large output currents demanded by the load.
7
OPA541
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.
FIGURE 3. Isolating Capacitive Loads.
APPLICATIONS CIRCUITS
10
1
0.1
1
10
100
|V V | (V)
S
OUT
SAFE OPERATING AREA
|I | (A)
O
T = +25C
T = +85C
C
C
AP, AM
BM, SM
T
C
= +125C
"M" Package only
FIGURE 2. Clamping Output for EMF-Generating Loads.
10F
OPA541
0.1F
0.1F
10F
V
S
D
2
D
1
L
Inductive or
EMF-Generating
Load
+V
S
D D : IN4003
1
2
OPA541
0.1
100k
R
2
10k
R
1
V
IN
20pF
L
OPA541
0.1
Slave
A = R /R
= 10
V
2
1
Master
10k
20pF
FIGURE 4. Replacing OPA501 with OPA541.
OPA541
1
2
8
R
CL
Not Required
OPA501
1
2
8
R
CL
R
CL
+
Pin 2 is "open" on OPA541.
8
OPA541
FIGURE 5. Paralleled Operation, Extended SOA.
FIGURE 6. Programmable Voltage Source.
0.1F
OPA541
0.1F
+35V
35V
0.5
10k
R
2
2.5k
R
1
V
IN
V
O
30pF
A = 1 + R /R = 5
V
2
1
0.1F
OPA541
0.1F
V
O
+60V
8V
DAC80-CBI-I
02mA
25k
0.3
050V
*
* Protects DAC
During Slewing
FIGURE 7. 16-Bit Programmable Voltage Source.
OPA541
V
OUT
+35V
35V
DAC702
0.5
30V to
+30V
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Digital Word
Input
MSB
LSB
100pF
=
+15V
15V
5k
1F
OPA27
10k
*
*
+15V
15V
23
18
19
20
10k
FB
1mA
* TCR
Tracking
Resistors
21
17
6
7
4
1F
1F
1F
1F
1F
2
3
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