OP162/OP262/OP462

–12–

REV. D

FREQUENCY – Hz

0.010

0.0001

20

10k

100

1k

0.001

20k

BANDWIDTH:

<10Hz TO 22kHz

Figure 38. THD+N vs. Frequency Graph

FREQUENCY – Hz

–40

–140

20

10k

100

1k

–90

20k

–50

–60

–70

–80

–100

–110

–120

–130

(0dBV)

Figure 39. Crosstalk vs. Frequency Graph

PCB Layout Considerations

Because the OP162/OP262/OP462 can provide gain at high

frequency, careful attention to board layout and component

selection is recommended. As with any high speed application,

a good ground plane is essential to achieve the optimum perfor-

mance. This can significantly reduce the undesirable effects of

ground loops and I

¥R losses by providing a low impedance refer-

ence point. Best results are obtained with a multilayer board

design with one layer assigned to ground plane.

Chip capacitors should be used for supply bypassing, with one

end of the capacitor connected to the ground plane and the

other end connected within 1/8 inch of each power pin. An

additional large tantalum electrolytic capacitor (4.7

mF–10 mF)

should be connected in parallel. This capacitor does not need to

be placed as close to the supply pins, as it is to provide current

for fast large-signal changes at the device’s output.

APPLICATION CIRCUITS

Single Supply Stereo Headphone Driver

Figure 40 shows a stereo headphone output amplifier that can

be run from a single +5 V supply. The reference voltage is

derived by dividing the supply voltage down with two 100 k

W

resistors. A 10

mF capacitor prevents power supply noise from

contaminating the audio signal and establishes an ac ground for

the volume control potentiometers.

The audio signal is ac coupled to each noninverting input

through a 10

mF capacitor. The gain of the amplifier is con-

trolled by the feedback resistors and is: (R2/R1) + 1. For this

example, the gain is 6. By removing R1 altogether, the amplifier

would have unity gain. A 169

W resistor is placed at the output

in the feedback network to short-circuit protect the output of

the device. This would prevent any damage to the device from

occurring if the headphone output became shorted. A 270

mF

capacitor is used at the output to couple the amplifier to the

headphone. This value is much larger than that used for the

input because of the low impedance of headphones, which can

range from 32

W to 600 W or more.

OP262-A

5V

169

270 F

47k

HEADPHONE

LEFT

L VOLUME

CONTROL

R1 = 10k

10 F

10 F

10k

5V

100k

10 F

100k

R2 = 50k

LEFT IN

OP262-B

5V

169

270 F

47k

HEADPHONE

RIGHT

10k

R VOLUME

CONTROL

10 F

RIGHT IN

R2 = 50k

10 F

R1 = 10k

Figure 40. Headphone Output Amplifier

Instrumentation Amplifier

Because of its high speed, low offset voltages and low noise

characteristics, the OP162/OP262/OP462 can be used in a wide

variety of high speed applications, including a precision instru-

mentation amplifier. Figure 41 shows an example of such an

application.

OP462-A

OP462-B

OP462-C

OP462-D

1k

10k

2k

1.9k

200

10 TURN

(OPTIONAL)

OUTPUT

1k

10k

2k

2k

Figure 41. A High Speed Instrumentation Amplifier