Datasheet
8
®
OPA2544
tion should trigger more than 25°C above the maximum
expected ambient condition of your application. This pro-
duces a junction temperature of 125°C at the maximum
expected ambient condition.
Depending on load and signal conditions, the thermal pro-
tection circuit may produce a duty-cycle modulated output
signal. This limits the dissipation in the amplifier, but the
rapidly varying output waveform may be damaging to some
loads. The thermal protection may behave differently de-
pending on whether internal dissipation is produced by
sourcing or sinking output current.
UNBALANCED POWER SUPPLIES
Some applications do not require equal positive and negative
output voltage swing. The power supply voltages of the
OPA2544 do not need to be equal. For example, a –7V
negative power supply voltage assures that the inputs of the
OPA2544 are operated within their linear common-mode
range, and that the output can swing to 0V. The V+ power
supply could range from 15V to 63V. The total voltage
(V– to V+) can range from 20V to 70V. With a 63V positive
supply voltage, the device may not be protected from dam-
age during short-circuits because of the larger V
CE
during
this condition.
OUTPUT PROTECTION
Reactive and EMF-generating loads can return load current
to the amplifier, causing the output voltage to exceed the
power supply voltage. This damaging condition can be
avoided with clamp diodes from the output terminal to the
power supplies as shown in Figure 2. Fast-recovery rectifier
diodes with a 4A or greater continuous rating are recom-
mended.
FIGURE 4. Bridge Drive Circuit.
3nF
B
1kΩ
10kΩ
10kΩ
A
20kΩ
G = –1
30Ω
Load
10kΩ
G = +3
V
IN
±10V
–35V
+35V
–35V
+35V
120Vp-p
(±60V)
FIGURE 3. Motor Drive Circuit. FIGURE 5. Paralleled Operation, Extended SOA.
G = – = –4
R
2
R
1
1Ω
0.01µF
R
2
20kΩ
R
1
5kΩ
1/2
OPA2544
V–
V+
V
IN
Motor
D
1
D
2
D
1
, D
2
: Motorola MUR420
Fast Recovery Rectifier.
A
V
= –R
2
/R
1
= –10
20pFParalleled operation not
recommended for input
signals that can cause
amplifiers to slew.
L
20pF
R
2
100kΩ
R
1
10kΩ
0.1Ω
10kΩ
0.1Ω
B
Slave
A
Master
V
IN