EL4452 View Datasheet(PDF) - Intersil

Part Name

Description

View to exact match

EL4452

Wideband Variable-Gain Amplifier with Gain of 10

Intersil 

EL4452

equivalent to four inches of unshielded wiring or 6 of

unterminated input transmission line. The oscillation has a

characteristic frequency of 500MHz. Often placing one’s

finger (via a metal probe) or an oscilloscope probe on the

input will kill the oscillation. Normal high-frequency

construction obviates any such problems, where the input

source is reasonably close to the input. If this is not possible,

one can insert series resistors of around 51Ω to de-Q the

inputs.

Signal Amplitudes

Signal input common-mode voltage must be between (V-)

+2.5V and (V+)-2.5V to ensure linearity. Additionally, the

differential voltage on any input stage must be limited to ±6V

to prevent damage. The differential signal range is ±0.5V in

the EL4452. The input range is substantially constant with

temperature.

The Ground Pin

The ground pin draws only 6µA maximum DC current, and

may be biased anywhere between (V-)+2.5V and (V+)-3.5V.

The ground pin is connected to the IC’s substrate and

frequency compensation components. It serves as a shield

within the IC and enhances input stage CMRR and

feedthrough over frequency, and if connected to a potential

other than ground, it must be bypassed.

Power Supplies

The EL4452 operates with power supplies from ±3V to ±15V.

The supplies may be of different voltages as long as the

requirements of the ground pin are observed (see the

Ground Pin section). The supplies should be bypassed close

to the device with short leads. 4.7µF tantalum capacitors are

very good, and no smaller bypasses need be placed in

parallel. Capacitors as small as 0.01µF can be used if small

load currents flow.

Single-polarity supplies, such as +12V with +5V can be

used, where the ground pin is connected to +5V and V- to

ground. The inputs and outputs will have to have their levels

shifted above ground to accommodate the lack of negative

supply.

The power dissipation of the EL4452 increases with power

supply voltage, and this must be compatible with the

package chosen. This is a close estimate for the dissipation

of a circuit:

PD=2×VS×IS, max+(VS-VO)×VO/RPAR

where

IS, max is the maximum supply current

VS is the ± supply voltage (assumed equal)

VO is the output voltage

RPAR is the parallel of all resistors loading the output

For instance, the EL4452 draws a maximum of 18mA. With

light loading, RPAR →∞ and the dissipation with ±5V

supplies is 180mW. The maximum supply voltage that the

device can run on for a given PD and other parameters is:

VS, max=(PD+VO2/RPAR)/(2IS+VO/RPAR)

The maximum dissipation a package can offer is:

PD, max = (TJ, max-TA, max) / θJA

Where

TJ,max is the maximum die temperature, 150°C for

reliability, less to retain optimum electrical performance

TA,max is the ambient temperature, 70°C for commercial

and 85°C for industrial range

θJAis the thermal resistance of the mounted package,

obtained from data sheet dissipation curves

The more difficult case is the SO-14 package. With a

maximum die temperature of 150°C and a maximum

ambient temperature of 85°C, the 65°C temperature rise and

package thermal resistance of 120°C/W gives a dissipation

of 542mW at 85°C. This allows the full maximum operating

supply voltage unloaded, but reduced if loaded.

Output Loading

The output stage of the EL4452 is very powerful. It can

typically source 80mA and sink 120mA. 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

delivering the 30mA continuous output given in the Absolute

Maximum Ratings table in this data sheet, or higher purely

transient currents.

Gain changes only 0.2% from no load to a 100Ω load. Heavy

resistive loading will degrade frequency response and

distortion for loads < 100Ω.

Capacitive loads will cause peaking in the frequency

response. If capacitive loads must be driven, a small-valued

series resistor can be used to isolate it. 12Ω to 51Ω should

suffice. A 22Ω series resistor will limit peaking to 1dB with

even a 220pF load.

8

Share Link: