Datasheet

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SBOS206E − DECEMBER 2001 − REVISED FEBRUARY 2007
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12
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
47
µ
F
+5V
−
5V
0.1
µ
F
0.1
µ
F
47
µ
F
R
6
100k
Ω
R
5
50m
Ω
R
2
1k
Ω
R
1
20k
Ω
R
3
20k
Ω
R
4
1k
Ω
V
O
OPA561
Flag
I
LIM
E/S
5
4
8
7
6
3
2
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:
1. Fully Integrated Solution
2.
Integrated Shutdown Circuitry for Send-and-Receive
Switching
3. Thermal Shutdown
4. Adjustable Current Limit
5. Shutdown Flag
6. Power Savings
7. Small PowerPAD package
12−Bit
DAC7513
MSP
430
REF3030
12−Bit
DAC7513
OPA561
+15V
3.3V
3.0V
1.2V
REF
3
3
R
L
R
1
R
F
V
CC
V
CC
0V to 1.2V sets
current limit
from 200mA to 1A
12V
PP
1A
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 to 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 1Ω
to 100Ω. The OPA561 is ideal for this type of load. The
transformer provides isolation and additional filtering. C
9
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.