EL4095CS datasheet(18/24 Pages) ELANTEC

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EL4095C

Video Gain ControlFaderMultiplexer

Applications Information

Contd

The EL4095 is connected as a unity-gain fader

with an LRC peaking network connected to the

A-input and an RC rolloff network connected to

the B-input The plot shows the range of peaking

controlled by the VGAIN input This circuit

would be useful for flattening the frequency re-

sponse of a system or for providing equalization

ahead of a lossy transmission line

Noise

The electrical noise of the EL4095 has two com-

ponents the voltage noise in series with aVIN is

5nV

0Hz wideband and there is a current noise

injected into bVIN of 35 pA

0Hz

The

output

noise will be

Vn out e

0 (A

V Vn input)

2 a (In input RF)2

and the input-referred noise is

Vn input-referred e

0 (V

n input)

2 a (In input RF AV)2

where AV is the fed-back gain of the EL4095

Here is a plot of input-referred noise vs AV

Input-Referred Noise vs Closed-Loop Gain

4095 – 35

Thus for a gain of three or more the fader has a

noise as good as an op-amp The only trade-off is

that the dynamic range of the input is reduced by

the gain due to the nonlinearity caused by

gained-up output signals

Power Dissipation

Peak die temperature must not exceed 150 C

This allows 75 C internal temperature rise for a

75 C ambient The EL4095 in the 14-pin PDIP

package has a thermal resistance of 65 CW and

can thus dissipate 115W at a 75 C ambient tem-

perature The device draws 20 mA maximum

supply current only 600 mW at g15V supplies

and the circuit has no dissipation problems in

this package

The

SO-14

surface-mount

package

has

105 CW thermal resistance with the EL4095

and only 714 mW can be dissipated at 75 C ambi-

ent temperature The EL4095 thus can be operat-

ed with g15V supplies at 75 C but additional

dissipation caused by heavy loads must be con-

sidered If this is a problem the supplies should

be reduced to g5V to g12V levels

The output will survive momentary short-cir-

cuits to ground but the large available current

will overheat the die and also potentially destroy

the circuit’s metal traces The EL4095 is reliable

within its maximum average output currents and

operating temperatures

EL4095C Macromodel

This macromodel is offered to allow simulation of

general EL4095 behavior

We have included

these characteristics

Small-signal frequency response

Signal path DC distoritons

Output loading effects

VGAIN I-V characteristics

Input impedance

VGAIN overdrive recovery

Off-channel feedthrough

delay

Output impedance over

100% gain error

frequency

FORCE operation

VIN characteristics and

sensitivity to parasitic

capacitance

These will give a good range of results of various

operating conditions but the macromodel does

not behave identically as the circuit in these ar-

eas

Temperature effects

Manufacturing tolerances

Signal overload effects

Supply voltage effects

Signal and VG operating range

Slewrate limitations

Current-limit

Noise

Video and high-frequency

Power supply interactions

distortions

Glitch and delay from

FORCE inputs

EL4095CS Datasheet(PDF) 18 Page - Elantec Semiconductor

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