12

DC bias the inputs at an appropriate common mode voltage

and AC couple the signal, or 2) ensure the driving signal is

within the common mode range of the EL2260/EL2460.

Settling Characteristics

The EL2260/EL2460 offer superb settling characteristics to

0.1%, typically in the 35ns to 40ns range. There are no

aberrations created from the input stage which often cause

longer settling times in other current feedback amplifiers.

The EL2260/EL2460 are not slew rate limited, therefore any

size step up to ±10V gives approximately the same settling

time.

As can be seen from the Long Term Settling Error curve, for

tails away to 0.01% in about 40µs. This is a thermal settling

error caused by a power dissipation differential (before and

mode configuration, this tail does not appear since the input

stage does not experience the large voltage change as in the

slightly greater than 100ns.

Power Dissipation

The EL2260/EL2460 amplifiers combine both high speed

and large output current drive capability at a moderate

supply current in very small packages. It is possible to

exceed the maximum junction temperature allowed under

certain supply voltage, temperature, and loading conditions.

To ensure that the EL2260/EL2460 remain within their

absolute maximum ratings, the following discussion will help

to avoid exceeding the maximum junction temperature.

The maximum power dissipation allowed in a package is

determined by its thermal resistance and the amount of

temperature rise according to:

The maximum power dissipation actually produced by an IC

is the total quiescent supply current times the total power

supply voltage plus the power in the IC due to the load, or

the current per amplifier. (To be more accurate, the

quiescent supply current flowing in the output driver

transistor should be subtracted from the first term because,

under loading and due to the class AB nature of the output

stage, the output driver current is now included in the second

term.)

In general, an amplifier’s AC performance degrades at

higher operating temperature and lower supply current.

Unlike some amplifiers, such as the LT1229 and LT1230, the

EL2260/EL2460 maintain almost constant supply current

over temperature so that AC performance is not degraded as

much over the entire operating temperature range. Of

course, this increase in performance doesn’t come for free.

Since the current has increased, supply voltages must be

limited so that maximum power ratings are not exceeded.

Each amplifier in the EL2260/EL2460 consume typically

7.5mA and maximum 10.0mA. The worst case power in an

IC occurs when the output voltage is at half supply, if it can

go that far, or its maximum value if it cannot reach

half supply. If we assume that the EL2260/EL2460 is used

for double terminated video cable driving applications

voltage is 2V, and the average output voltage is 1.4V. If we

and conditions according to:

The curves do not include heat removal or forcing air, or the

simple fact that the package will probably be attached to a

circuit board, which can also provide some form of heat

removal. Larger temperature and voltage ranges are

possible with heat removal and forcing air past the part.

Current Limit

The EL2260/EL2460 have internal current limits that protect

the circuit in the event of the output being shorted to ground.

This limit is set at 100mA nominally and reduces with

junction temperature. At a junction temperature of 150°C, the

current limits at about 65mA. If any one output is shorted to

ground, the power dissipation could be well over 1W, and

much greater if all outputs are shorted. Heat removal is

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Supply Voltage vs Ambient Temperature

for All Packages of EL2260/EL2460

EL2260, EL2460