AD815 Analog Devices, AD815 Datasheet - Page 14

• Manufacturer Part Number: AD815
• Description: High Output Current Differential Driver
• Manufacturer: Analog Devices

Specifications of AD815

• -3db Bandwidth: 120MHz
• Slew Rate: 900V/µs
• Vos: 10mV
• Ib: 2µA
• # Opamps Per Pkg: 2
• Input Noise (nv/rthz): 1.85nV/rtHz
• Vcc-vee: 10V to 36V
• Isy Per Amplifier: 40mA
• Packages: DDPAK,SIP,SOIC

AD815
If a resistor (R
+ input of Amp 1, negative feedback is provided which closes
the loop. An input resistor (R
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 ± R
R
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.
(OPTIONAL)
I
. Or the single-ended-to-differential gain will be 2 × R
V
IN
(50 )
Figure 55. Single-Ended-to-Differential Driver
250
499
R
I
AMP1
AMP2
F
) is connected from the output of Amp 2 to the
10
11
4
5
1/2
AD815
1/2
AD815
499
499
+15V
–15V
R
R
8
A
A
7
V
V
CC
CC
6
9
~
499
I
0.1 F
) will make the circuit look like a
20pF
R
R
499
R
499
F
0.1 F
B
B
10 F
10 F
50
50
(OPTIONAL)
F
/R
100
I.
F
/
–14–
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°.
Figure 56. AD815 Video Distribution Amp Driving
12 Video Cables
VIDEO IN
75
499
499
100
100
499
499
10
11
5
4
AD815
+15V
–15V
8
7
6
9
0.1 F
0.1 F
12
10 F
10 F
75
12
VIDEO OUT
TO 75
CABLES
REV. C