OPA561 datasheet(12/17 Pages) TI1

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OPA561

SBOS206E − DECEMBER 2001 − REVISED FEBRUARY 2007

www.ti.com

APPLICATIONS CIRCUITS

The high output current and low supply of the OPA561

makes it a good candidate for driving laser diodes and

thermo electric coolers. Figure 9 shows the OPA561

configured as a laser diode driver.

+1V/+1A

µF

+5V

−5V

0.1

µF

0.1

µF

100k

Ω

50m

Ω

20k

Ω

20k

Ω

OPA561

Flag

LIM

E/S

Figure 9. Laser Diode Driver

PROGRAMMABLE POWER SUPPLY

Figure 10 shows the OPA561 configured with the

MSP430, REF3030, and DAC7513 as a space-saving,

low-cost, programmable power-supply solution. This solu-

tion features low-voltage operation, small-size packages,

(DAC7513 in SOT23-8, REF3030 in SOT23-3) and low

cost.

POWER-LINE COMMUNICATION MODEM

The OPA561 is well suited to drive AC power lines for

low-speed communications applications. It provides an

easily implemented, reliable solution that is superior to

discrete power transistor circuits. Advantages include:

Fully Integrated Solution

Integrated Shutdown Circuitry for Send

-and-Receive

Switching

Thermal Shutdown

Adjustable Current Limit

Shutdown Flag

Power Savings

Small PowerPAD package

12−Bit

DA C 7513

MSP

430

RE F30 30

12−Bit

DA C 7513

OPA 561

+15V

3.3V

3.0 V

1.2 V

REF

VCC

0V to 1.2V sets

current limit

fr om 200mA to 1A

12VPP

0V to 3V

Figure 10. Programmable Power Supply

Typically such a system consists of a microcontroller, a

modem IC and the power line interface circuitry. See

Figure 11 for the half-duplex power line communication

system.

It uses a synchronous FSK-modem, capable of 600 and

1200-baud data rates, and supports two different FSK

channels in the 60kHz to 80kHz range. A microcontroller

such as the MSP430 is used to control the modem IC.

The OPA561 analog interface circuitry drives the FSK

modem signals on the AC power line. It filters the transmit

signal

(ATO)

from

the

ST7536

suppress

the

2nd-harmonic distortion of the transmit signal. It also

amplifies the ATO signal and provides the very low output

impedance necessary to properly drive the line. The

impedance of a typical power line at 70kHz ranges from 1

Ω

to 100

Ω. The OPA561 is ideal for this type of load. The

transformer provides isolation and additional filtering. C9

prevents 50/60Hz current from flowing in the transformer.

This capacitor must be chosen carefully for proper voltage

rating and safety characteristics.

The receive input signal is amplified (G = 100) and applied

to the modem IC. The OPA561 is disabled in receive mode

to avoid loading the line.

Not Recommended for New Designs

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