el2260cn Intersil Corporation, el2260cn Datasheet - Page 12

• Manufacturer Part Number: el2260cn
• Description: Dual/quad 130mhz Current Feedback Amplifiers
• Manufacturer: Intersil Corporation

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
A
tails away to 0.01% in about 40µs. This is a thermal settling
error caused by a power dissipation differential (before and
after the voltage step). For A
mode configuration, this tail does not appear since the input
stage does not experience the large voltage change as in the
non-inverting mode. With A
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
where N is the number of amplifiers per package, and I
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.
V
= +1, there is approximately a 0.035% residual which
P
DMAX
P
DMAX
=
=
N
T
-------------------------------------------- -
u
JMAX
§
¨
©
2
u
T
V
–
JA
S
V
T
u
V
12
AMAX
= -1, 0.01% settling time is
I
= -1, due to the inverting
S
+
V
S
–
V
OUT
u
V
--------------- -
OUT
R
L
·
¸
¹
EL2260, EL2460
S
is
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
(R
voltage is 2V, and the average output voltage is 1.4V. If we
set the two P
for V
and conditions according to:
The following curve shows supply voltage (±V
temperature for the various packages assuming A
R
case conditions (I
V
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
OUT
L
L
= 150, and V
= 150:), and the gain = +2, then the maximum output
S
, we can get a family of curves for various packages
peak = 2V).
V
S
Dmax
=
R
-------------------------------------------------------------- -
------------------------------------------------------------------------------------------ -
Supply Voltage vs Ambient Temperature
OUT
L
for All Packages of EL2260/EL2460
S
u
equations equal to each other, and solve
= 10mA and all amplifiers operating at
T
peak = 2V. The curves include worst
JMAX
2
N
u
u
I
S
T
JA
u
–
T
R
AMAX
L
+
V
OUT
+
V
OUT
S
) vs.
V
= + 2,