Datasheet

OPA548
13
SBOS070B
www.ti.com
avoided with clamp diodes from the output terminal to the
power supplies, as shown in Figure 14. Schottky rectifier
diodes with a 5A or greater continuous rating are recom-
mended.
VOLTAGE SOURCE APPLICATION
Figure 15 illustrates how to use the OPA548 to provide an
accurate voltage source with only three external resistors.
First, the current limit resistor, R
CL
, is chosen according to
the desired output current. The resulting voltage at the I
LIM
pin is constant and stable over temperature. This voltage,
V
CL
, is connected to the noninverting input of the op amp and
used as a voltage reference, thus eliminating the need for an
external reference. The feedback resistors are selected to
gain V
CL
to the desired output voltage level.
PROGRAMMABLE POWER SUPPLY
A programmable source/sink power supply can easily be
built using the OPA548. Both the output voltage and output
current are user-controlled. See Figure 16 for a circuit using
potentiometers to adjust the output voltage and current while
Figure 17 uses DACs. An LED tied to the E/S pin through a
logic gate indicates if the OPA548 is in thermal shutdown.
FIGURE 13. Output Disable and Thermal Shutdown Status with Dual Supplies.
FIGURE 12. Output Disable and Thermal Shutdown Status
with a Single Supply.
FIGURE 14. Motor Drive Circuit.
OPA548
V+
E/S
Open Drain
(Output Disable)
HCT
(Thermal Status
Shutdown)
V–
OPA548
V+
E/S
NOTE: (1) Optional—may be required to limit leakage
current of optocoupler at high temperatures.
V–
(1)
6
1
2
4N38
Optocoupler
5
4
HCT or TTL In
5V
6
2
1
4N38
Optocoupler
5
4
Zetex
ZVN3310
TTL Out
7.5kΩ
1W
5V
G = – = –4
R
2
R
1
10Ω
(Carbon)
0.01µF
R
2
20kΩ
R
1
5kΩ
OPA548
V–
V+
V
IN
Motor
D
1
D
2
D
1
, D
2
: Motorola MUR410.