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參數(shù)資料
| 型號(hào)： | HA5024IP |
| 廠商： | HARRIS SEMICONDUCTOR |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | Quad 125MHz Video Current Feedback Amplifier with Disable |
| 中文描述： | VIDEO AMPLIFIER, PDIP20 |
| 封裝： | PLASTIC, DIP-20 |
| 文件頁(yè)數(shù)： | 8/16頁(yè) |
| 文件大?。?/td> | 177K |
| 代理商： | HA5024IP |
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8
The circuit shown in Figure 8 is a simplified schematic of the
enable/disable function. The large value resistors in series with
the DISABLE pin makes it appear as a current source to the
driver. When the driver pulls this pin low current flows out of the
pin and into the driver. This current, which may be as large as
350
μ
A when external circuit and process variables are at their
extremes, is required to insure that point “A” achieves the
proper potential to disable the output.The driver must have the
compliance and capability of sinking all of this current.
When V
CC
is +5V the DISABLE pin may be driven with a
dedicated TTL gate. The maximum low level output voltage
of the TTL gate, 0.4V, has enough compliance to insure that
the amplifier will always be disabled even though D
1
will not
turn on, and the TTL gate will sink enough current to keep
point “A” at its proper voltage. When V
CC
is greater than +5V
the DISABLE pin should be driven with an open collector
device that has a breakdown rating greater than V
CC
.
Referring to Figure 8, it can be seen that R
6
will act as a pull-up
resistor to +V
CC
if the DISABLE pin is left open. In those cases
where the enable/disable function is not required on all circuits
some circuits can be permanently enabled by letting the
DISABLE pin float. If a driver is used to set the enable/disable
level, be sure that the driver does not sink more than 20
μ
A
when the DISABLE pin is at a high level. TTL gates, especially
CMOS versions, do not violate this criteria so it is permissible to
control the enable/disable function with TTL.
+V
CC
Typical Applications
Four Channel Video Multiplexer
Referring to the amplifier U
1A
in Figure 9, R
1
terminates the
cable in its characteristic impedance of 75
, and R
4
back
terminates the cable in its characteristic impedance. The
amplifier is set up in a gain configuration of +2 to yield an
overall network gain of +1 when driving a double terminated
cable. The value of R
3
can be changed if a different network
gain is desired. R
5
holds the disable pin at ground thus
inhibiting the amplifier until the switch, S
1
, is thrown to
position 1. At position 1 the switch pulls the disable pin up to
the plus supply rail thereby enabling the amplifier. Since all
of the actual signal switching takes place within the amplifier,
its differential gain and phase parameters, which are 0.03%
and 0.03 degrees respectively, determine the circuit’s
performance. The other three circuits, U
1B
through U
1D
,
operate in a similar manner.
When the plus supply rail is 5V the disable pin can be driven by
a dedicated TTL gate as discussed earlier. If a multiplexer IC or
its equivalent is used to select channels its logic must be break
before make. When these conditions are satisfied the
HA5024IP is often used as a remote video multiplexer, and the
multiplexer may be extended by adding more amplifier ICs.
Low Impedance Multiplexer
Two common problems surface when you try to multiplex
multiple high speed signals into a low impedance source
such as an A/D converter. The first problem is the low source
impedance which tends to make amplifiers oscillate and
causes gain errors. The second problem is the multiplexer
which supplies no gain, introduces all kinds of distortion and
limits the frequency response. Using op amps which have an
enable/disable function, such as the HA5024, eliminates the
multiplexer problems because the external mux chip is not
needed, and the HA5024 can drive low impedance (large
capacitance) loads if a series isolation resistor is used.
R
15K
R
7
15K
ENABLE/DISABLE INPUT
D
1
Q
P3
R
8
Q
P18
A
R
33
R
10
FIGURE 8. SIMPLIFIED SCHEMATIC OF ENABLE/DISABLE
FUNCTION
NOTES:
18. U
1
is HA5024IP.
19. All resistors in
.
20. S
1
is break before make.
21. Use ground plane.
FIGURE 9. FOUR CHANNEL VIDEO MULTIPLEXER
+
-
U
1A
+
-
U
1B
+
-
+
-
VIDEO
INPUT
#1
VIDEO OUTPUT
75
LOAD
TO
R
4
75
3
2
4
R
1
75
R
3
681
R
5
2000
R
2
681
1
R
6
75
R
8
681
R
7
681
R
9
75
10
8
9
7
R
10
2000
1R
21
100
2
3
4
VIDEO
INPUT
#3
R
11
75
13
12
14
15
-5V
11
R
13
681
R
12
681
R
15
2000
R
14
75
+5V
S
1
ALL
OFF
VIDEO
INPUT
#4
R
16
75
18
17
6
20
R
19
75
R
20
2000
R
17
681
R
18
681
U
1C
U
1D
+5V
+5V IN
+5V
0.1
μ
F
10
μ
F
0.1
μ
F
10
μ
F
-5V IN
-5V
100
(NOTE 17)
100
(NOTE 17)
100
(NOTE 17)
100
(NOTE 17)
HA5024
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| HA5024EVAL | Quad 125MHz Video Current Feedback Amplifier with Disable |
| HA5025 | Quad, 125MHz Video Current Feedback Amplifier |
| HA5025IB | Quad, 125MHz Video Current Feedback Amplifier |
| HA5025IP | Quad, 125MHz Video Current Feedback Amplifier |
| HA5025EVAL | Triple, 125MHz Video Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HA5024IPZ | 功能描述:視頻放大器 W/ANNEAL OPAMP 4X 12 5MHZ CFB DISABLE RoHS:否 制造商:ON Semiconductor 通道數(shù)量:4 電源類型: 工作電源電壓:3.3 V, 5 V 電源電流: 最小工作溫度: 最大工作溫度: 封裝 / 箱體:TSSOP-14 封裝:Reel |
| HA5025 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Quad, 125MHz Video Current Feedback Amplifier |
| HA5025 WAF | 制造商:Harris Corporation 功能描述: 制造商:Intersil Corporation 功能描述: |
| HA5025_03 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Quad, 125MHz Video Current Feedback Amplifier |
| HA5025EVAL | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Triple, 560MHz, Low Power, Video Operational Amplifier |
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