el8203 Intersil Corporation, el8203 Datasheet - Page 12

• Manufacturer Part Number: el8203
• Description: 500mhz Rail-to-rail Amplifiers
• Manufacturer: Intersil Corporation

For sourcing:
For sinking:
PD
Where:
By setting the two PD
can solve the output current and R
overheat.
Power Supply Bypassing and Printed Circuit
Board Layout
As with any high frequency device, a good printed circuit
board layout is necessary for optimum performance. Lead
lengths should be as short as possible. The power supply
pin must be well bypassed to reduce the risk of oscillation.
For normal single supply operation, where the V
connected to the ground plane, a single 4.7µF tantalum
capacitor in parallel with a 0.1µF ceramic capacitor from V
to GND will suffice. This same capacitor combination should
be placed at each supply pin to ground if split supplies are to
be used. In this case, the V
supply rail.
For good AC performance, parasitic capacitance should be
kept to a minimum. Use of wire wound resistors should be
avoided because of their additional series inductance. Use
of sockets should also be avoided if possible. Sockets add
parasitic inductance and capacitance that can result in
compromised performance. Minimizing parasitic capacitance
at the amplifier’s inverting input pin is very important. The
feedback resistor should be placed very close to the
inverting input pin. Strip line design techniques are
recommended for the signal traces.
Typical Applications
VIDEO SYNC PULSE REMOVER
Many CMOS analog to digital converters have a parasitic
latch up problem when subjected to negative input voltage
levels. Since the sync tip contains no useful video
information and it is a negative going pulse, we can chop it
off. Figure 32 shows a gain of 2 connections. Figure 33
shows the complete input video signal applied at the input,
PD
MAX
V
I
V
each channel
R
channel
I
MAX
SMAX
LOADi
S
OUTi
LOADi
= Total supply voltage
=
=
= Maximum output voltage of the application for
= Maximum quiescent supply current
V
= Load current for each channel
V
= Load resistance tied to ground for each
S
S
×
×
I
I
SMAX
SMAX
MAX
+
+
Σ V
Σ V
(
(
equations equal to each other, we
OUTi
S
S
–
- pin becomes the negative
12
V
OUTi
–
V
LOADi
S
-
)
) I
×
×
V
---------------- -
LOADi
OUTi
R
to avoid the device
Li
EL8202, EL8203, EL8403
S
- pin is
S
+
as well as the output signal with the negative going sync
pulse removed.
MULTIPLEXER
Besides the normal power down usage, the ENABLE pin of
the EL8202 can be used for multiplexing applications. Figure
34 shows two EL8202 with the outputs tied together, driving
a back terminated 75Ω video load. A 2V
is applied to Amp A and a 1V
to Amp B. Figure 33 shows the ENABLE signal and the
resulting output waveform at V
before-make operation of the multiplexing. Amp A is on and
V
signal is low and turns off in about 25ns when the ENABLE
signal is high. About 200ns later, Amp B turns on and V
passed through to the output. The break-before-make
operation ensures that more than one amplifier isn’t trying to
drive the bus at the same time.
IN1
V
IN
is passed through to the output when the ENABLE
75Ω
FIGURE 32. SYNC PULSE REMOVER
1K
FIGURE 33. VIDEO SIGNAL
V
OUT
V
+
-
1K
5V
IN
M = 10µs/DIV
V
V
S+
S-
P-P
OUT
75Ω
2MHz sine wave is applied
. Observe the break-
P-P
2MHz sine wave
75Ω
1V
0.5V
0V
1V
0.5V
0V
V
OUT
IN2
is