EL4441CS datasheet(12/16 Pages) ELANTEC

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EL4421C22C41C42C43C44C

Multiplexed-Input Video Amplifiers

Applications Information

Contd

behavior is assured In any event keeping signals

within guaranteed compliance limits will assure

freedom from overload problems

The input and output ranges are substantially

constant with temperature

Power Supplies

The mux-amps work well on any supplies from

3V to g15V The supplies may be of different

voltages as long as the requirements of the Gnd

pin are observed (see the Switching Characteris-

tics section for a discussion) The supplies should

be bypassed close to the device with short leads

mF tantalum capacitors are very good and no

smaller bypasses need be placed in parallel Ca-

pacitors as small as 001

mF can be used if small

load currents flow

Single-polarity supplies

such as a12V with

5V can be used as described in the Switching

Characteristics section The inputs and outputs

will have to have their levels shifted above

ground to accommodate the lack of negative sup-

ply

The dissipation of the mux-amps increases with

power supply voltage and this must be compati-

ble with the package chosen This is a close esti-

mate for the dissipation of a circuit

PD e 2VScIs maxa(VS–VO)cVO RPAR

Where

Is max is the maximum supply cur-

rent

VS is the g supply voltage (as-

sumed equal)

VO if the output voltage

RPAR is the parallel of all resistors

loading the output

For instance the EL4422 draws a maximum of

14 mA and we might require a 2V peak output

into 150

X and a 270X a270X feedback divider

The RPAR is 117X The dissipation with g5V

supplies is 191 mW The maximum Supply volt-

age that the device can run on for a given PD and

the other parameter is

VS maxe(PDaVO2 RPAR)2IsaVO RPAR)

The maximum dissipation a package support is

PD max e (TD max-TA max)RTH

Where TD max is the maximum die temper-

ature 150 C for reliability less to re-

tain optimum electrical performance

TA max is the ambient temperature

70 for commercial and 85 C for indus-

trial range

RTH is the thermal resistance of the

mounted package obtained from data

sheet dissipation curves

The most difficult case is the SO-8 package With

a maximum die temperature of 150 C and a maxi-

mum ambient temperature of 85

the 65 temper-

ature rise and package thermal resistance of

170 W gives a maximum dissipation of 382 mW

This allows a maximum supply voltage of g92V

for the EL4422 operated in our example If the

EL4421 were driving a light load (RPAR

x%)

it could operate on g15V supplies at a 70 maxi-

mum ambient

The EL4441 through EL4444 can operate on

12V supplies in the SO package and all parts

can be powered by g15V supplies in DIP pack-

ages

Output Loading

The output stage of the mux-amp is very power-

ful and can source 80 mA and sink 120 mA Of

course this is too much current to sustain and

the part will eventually be destroyed by excessive

dissipation or by metal traces on the die opening

The metal traces are completely reliable while de-

livering the 30 mA continuous output given in

the Absolute Maximum Ratings table in this

data sheet or higher purely transient currents

Gain or gain accuracy degrades only 10% from

no load to 100

X load Heavy resistive loading will

degrade frequency response and video distortion

only a bit becoming noticeably worse for loads

100

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