AD815A 查看數據表（PDF） - Analog Devices

零件编号

产品描述 (功能)

比赛名单

AD815A

High Output Current Differential Driver

Analog Devices 

AD815

~20pF

+15V

RF

499⍀

RI

499⍀

VCC

0.1␮F 10␮F

(OPTIONAL)

VIN

9

13

1/2

50⍀

AMP1 AD815 11

10

250

(50⍀)

(OPTIONAL)

RA

499⍀

RA

499⍀

RB

499⍀

RB

499⍀

100⍀

15

1/2

AMP2 AD815 14

16

12 VCC

50⍀

–15V

0.1␮F 10␮F

Figure 55. Single-Ended-to-Differential Driver

If a resistor (RF) is connected from the output of Amp 2 to the

+ input of Amp 1, negative feedback is provided which closes

the loop. An input resistor (RI) will make the circuit look like a

conventional inverting op amp configuration with differential

outputs. The inverting input to this dual output op amp becomes

Pin 4, the positive input of Amp 1.

The gain of this circuit from input to either output will be ± RF/

RI. Or the single-ended-to-differential gain will be 2 × RF/RI.

The differential outputs can be applied to the primary of a

transformer. If each output can swing ± 10 V, the effective swing

on the transformer primary is 40 V p-p. The optional capacitor

can be added to prevent any dc current in the transformer due

to dc offsets at the output of the AD815.

Twelve Channel Video Distribution Amplifier

The high current of the AD815 enables it to drive up to twelve

standard 75 Ω reverse terminated video loads. Figure 56 is a

schematic of such an application.

The input video signal is terminated in 75 Ω and applied to the

noninverting inputs of both amplifiers of the AD815. Each

amplifier is configured for a gain of two to compensate for the

divide-by-two feature of each cable termination. Six separate

75 Ω resistors for each amplifier output are used for the cable

back termination. In this manner, all cables are relatively

independent of each other and small disturbances on any cable

will not have an effect on the other cables.

When driving six video cables in this fashion, the load seen by

each amplifier output is resistive and is equal to 150 Ω/6 or

25 Ω. The differential gain is 0.05% and the differential phase is

0.45°.

+15V

499⍀

0.1␮F

10␮F

12 ؋ 75⍀

499⍀

10

100⍀

9

13

11

VIDEO IN

75⍀

AD815

100⍀

16

15

14

12

12 ؋

VIDEO OUT

TO 75⍀

CABLES

499⍀ 499⍀

0.1␮F 10␮F

–15V

Figure 56. AD815 Video Distribution Amp Driving

12 Video Cables

–14–

REV. D

Share Link: