®

OPA2541

6

The internal current limit will not provide short-circuit

protection in most applications. When the amplifier output is

shorted to ground, the full power supply voltage is im-

pressed across the conducting output transistor. For in-

stance, with V

S = ±35V, a short circuit to ground would

impress 35V across the conducting power transistor. The

maximum safe output current at this voltage is 1.8A, so the

internal current limit would not protect the amplifier. The

unit-to-unit variation and temperature dependence of the

internal current limit suggest that it be used to handle

abnormal conditions and not activated in commonly encoun-

tered circuit operation.

Reactive, or EMF generating loads such as DC motors can

present demanding SOA requirements. With a purely reac-

tive load, output voltage current occurs when the output

voltage is zero and the voltage across the conducting transis-

tor is equal to the full power supply voltage. See Burr-

Brown Application Note AN-123 for further information on

evaluating SOA.

Applications with inductive or EMF-generating loads which

can produce “kick back” voltage surges to the amplifiers

should include clamp diodes from the output terminals to the

power supplies. These diodes should be chosen to limit the

peak amplifier output voltage surges to less than 2V beyond

the power supply rail voltage. Common 1A rated rectifier

diodes will suffice in most applications.

APPLICATIONS CIRCUITS

FIGURE 2. Clamping Output for EMF-Generating Loads.

0.1µF

0.1µF

+35V

–35V

A

V = 1 + R2/R1 = 5

R

2

10k

Ω

R

1

2.5k

Ω

V

IN

30pF

0.5

Ω

V

O

FIGURE 3. Isolating Capacitive Loads.

FIGURE 1. Safe Operating Area.

0.1µF

L

10µF

0.1µF

10µF

+V

S

+

–V

S

D

1

D

2

Inductive-

or EMF-

Generating

Load

D

1 – D2: IN4003

+

FIGURE 4. Paralleled Operation, Extended SOA.

A

V = –R2/R1 = –10

20pF

L

20pF

R

2

100k

Ω

R

1

10k

Ω

0.1

Ω

10k

Ω

0.1

Ω

B

Slave

A

Master

V

IN

10

1.0

0.1

1

100

|V

S – VOUT| (V)

SAFE OPERATING AREA

10

T

C = +25°C

T

C = +85°C

T

C = +125°C

*Depending on temperature, maximum output may

be restricted by internal current limit. See output

current specifications and typical curves.

*