HA5024 데이터 시트보기 (PDF) - Renesas Electronics
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HA5024 Datasheet PDF : 17 Pages
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HA5024
needed, and the HA5024 can drive low impedance (large
capacitance) loads if a series isolation resistor is used.
VIDEO
INPUT
#1
R1
75
(NOTE 17)
100 3
2 +-
1
U1A 4
R3
681
R2
681
R4
75
R5
2000
(NOTE 17) 100
8
9 +-
10
R6
U1B 7
75
R8
R7
681
681
R9
75
R10
2000
-5V
VIDEO
INPUT
#3
(NOTE 17)
100 13
15
12 +-
11
R14
75
R11
U1C 14
75
R13
681
R12
681
R15
2000
+5V
VIDEO
INPUT
#4
(NOTE 17)
100 18 6
19 +-
20
R19
75
R16
U1D 17
75
R18
681
R17
681
R20
2000
VIDEO OUTPUT
TO 75 LOAD
1 R21
100
+5V
2
3
S1
4
ALL
OFF
+5V IN
+5V -5V IN
-5V
0.1F
10F
0.1F
10F
NOTES:
18. U1 is HA5024IP.
19. All resistors in
20. S1 is break before make.
21. Use ground plane.
FIGURE 9. FOUR CHANNEL VIDEO MULTIPLEXER
Referring to Figure 10, both inputs are terminated in their
characteristic impedance; 75 is typical for video
applications. Since the drivers usually are terminated in their
characteristic impedance the input gain is 0.5, thus the
amplifiers, U2, are configured in a gain of +2 to set the circuit
gain equal to one. Resistors R2 and R3 determine the amplifier
gain, and if a different gain is desired R2 should be changed
according to the equation G = (1 + R3/R2). R3 sets the
frequency response of the amplifier so you should refer to the
manufacturers data sheet before changing its value. R5, C1
and D1 are an asymmetrical charge/discharge time circuit
which configures U1 as a break before make switch to prevent
both amplifiers from being active simultaneously. If this design
is extended to more channels the drive logic must be designed
to be break before make. R4 is enclosed in the feedback
loop of the amplifier so that the large open loop amplifier
FN3550 Rev 6.00
February 8, 2006
gain of U2 will present the load with a small closed loop
output impedance while keeping the amplifier stable for all
values of load capacitance.
The circuit shown in Figure 10 was tested for the full range of
capacitor values with no oscillations being observed; thus,
problem one has been solved.The frequency and gain
characteristics of the circuit are now those of the amplifier
independent of any multiplexing action; thus, problem two
has been solved. The multiplexer transition time is
approximately 15s with the component values shown.
Page 9 of 17
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