OPA548F datasheet(8/24 Pages) TI

8 / 24 page

OPA548

SBOS070B

www.ti.com

APPLICATIONS INFORMATION

Figure 1 shows the OPA548 connected as a basic noninverting

amplifier. The OPA548 can be used in virtually any op amp

configuration.

Power-supply terminals should be bypassed with low series

impedance capacitors. The technique shown in Figure 7,

using a ceramic and tantalum type in parallel is recom-

mended. In addition, we recommend a 0.01

µF capacitor

between V+ and V– as close to the OPA548 as possible.

Power-supply wiring should have low series impedance.

With the OPA548, the simplest method for adjusting the

current limit uses a resistor or potentiometer connected

between the ILIM pin and V– according to the Equation 1:

LIM

= (

)(

)

15000 4 75

13750

–

Ω

The low-level control signal (0

µA to 330µA) also allows the

current limit to be digitally controlled.

See Figure 3 for a simplified schematic of the internal

circuitry used to set the current limit. Leaving the ILIM pin

open programs the output current to zero, while connecting

ILIM directly to V– programs the maximum output current limit,

typically 5A.

SAFE OPERATING AREA

Stress on the output transistors is determined both by the

output current and by the output voltage across the conduct-

ing output transistor, VS – VO. The power dissipated by the

output transistor is equal to the product of the output current

and the voltage across the conducting transistor, VS – VO.

The Safe Operating Area (SOA curve, Figure 2) shows the

permissible range of voltage and current.

FIGURE 1. Basic Circuit Connections.

POWER SUPPLIES

The OPA548 operates from single (+8V to +60V) or dual

(

±4V to ±30V) supplies with excellent performance. Most

behavior remains unchanged throughout the full operating

voltage range. Parameters which vary significantly with oper-

ating voltage are shown in the typical characteristic curves.

Some applications do not require equal positive and negative

output voltage swing. Power-supply voltages do not need to

be equal. The OPA548 can operate with as little as 8V

between the supplies and with up to 60V between the

supplies. For example, the positive supply could be set to

55V with the negative supply at –5V, or vice-versa.

ADJUSTABLE CURRENT LIMIT

The OPA548 features an accurate, user-selected current

limit. Current limit is set from 0A to 5A by controlling the input

to the ILIM pin. Unlike other designs which use a power

resistor in series with the output current path, the OPA548

senses the load indirectly. This allows the current limit to be

set with a 0

µA to 330µA control signal. In contrast, other

designs require a limiting resistor to handle the full output

current (5A in this case).

FIGURE 2. Safe Operating Area.

The safe output current decreases as VS – VO increases.

Output short-circuits are a very demanding case for SOA. A

short-circuit to ground forces the full power-supply voltage

(V+ or V–) across the conducting transistor. Increasing the

case temperature reduces the safe output current that can be

tolerated without activating the thermal shutdown circuit of

the OPA548. For further insight on SOA, consult Application

Bulletin SBOA022.

AMPLIFIER MOUNTING

Figure 4 provides recommended solder footprints for both the

TO-220 and DDPAK power packages. The tab of both pack-

ages is electrically connected to the negative supply, V–. It may

be desirable to isolate the tab of the TO-220 package from its

G = 1+

E/S

LIM

(1)

0.1

µF(2)

µF

OPA548

V–

V+

µF

0.1

µF(2)

0.01

µF(2)

NOTES: (1) I

LIM connected to V– gives the maximum

current limit, 5A (peak). (2) Connect capacitors directly to

package power-supply pins.

V

S – VO (V)

100

SAFE OPERATING AREA

0.1

Pulse Operation Only

(Limit rms current to

≤ 3A)

Current-Limited

Output current can

be limited to less

than 3A—see text.

C = 125°C

C = 85°C

C = 25°C

(1)

OPA548F Datasheet(PDF) 8 Page - Texas Instruments

OPA548F Datasheet(HTML) 8 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL