EL4421CN Elantec Semiconductor, Inc. (acquired by Intersil), EL4421CN Datasheet - Page 11

• Manufacturer Part Number: EL4421CN
• Description: Multiplexed-input Video Amplifier
• Manufacturer: Elantec Semiconductor, Inc. (acquired by Intersil)

Applications Information
The logic input(s) and ground pin are shifted
2 5V above system ground to correctly bias the
mux-amp Of course all the signal inputs and
output will have to be shifted 2 5V above system
ground to ensure proper signal path biasing
A final caution the ground pin is also connected
to the IC’s substrate and frequency compensation
components The ground pin must be returned to
system ground by a short wire or nearby bypass
capacitor In figure 2 the 22 K
serve to isolate the bypassed ground pin from the
Signal Amplitudes
Signal input and output voltages must be be-
tween (V
linearity Additionally the differential voltage on
any input stage must be limited to
vent damage In unity-gain connections any in-
put could have
would be at
tial limit Higher-gain circuit applications divide
the output voltage and allow for larger outputs
For instance at a gain of
a
5V supply noise
b
)
a
g
3V putting us at our 6V differen-
2 5V and (V
g
3V applied and the output
a
2 the maximum input
a
)
b
2 5V to ensure
resistors also
g
6V to pre-
EL4421C 22C 41C 42C 43C 44C
Contd
Multiplexed-Input Video Amplifiers
11
is again
EL4443 or EL4444 can be wired for inverting
gain with even more amplitude possible
The output and positive inputs respond to over-
loading amplitudes correctly that is they simply
clamp and remain monotonic with increasing
where the
by large outputs This occurs mainly in unity-
gain connections and only happens for negative
inputs The overloaded input cannot control the
feedback loop correctly and the output can be-
come non-monotonic A typical scenario has the
circuit running on
unity gain and the input is the maximum
Negative input extremes can cause the output to
jump from
er happen if the input is restricted to
which is the guaranteed maximum input compli-
ance with
with greater supply voltages Connecting the
feedback network with a divider will prevent the
overloaded output voltage from being large
enough to overload the
a
input overdrive A condition exists however
g
b
3V and the output swing is
g
b
input of an active stage is overdriven
5V supplies and is not a problem
3V to around
g
5V supplies connected for
b
b
input and monotonic
2 3V This will nev-
g
6V The
g
g
2 5V
3V