OPA548F datasheet(13/24 Pages) TI

13 / 24 page

OPA548

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, RCL, is chosen according to

the desired output current. The resulting voltage at the ILIM

pin is constant and stable over temperature. This voltage,

VCL, 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 VCL 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)

4N38

Optocoupler

HCT or TTL In

4N38

Optocoupler

Zetex

ZVN3310

TTL Out

7.5k

Ω

G = –

= –4

Ω

(Carbon)

0.01µF

20k

Ω

OPA548

V–

V+

Motor

1, D2 : Motorola MUR410.

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