EL1507CL Intersil, EL1507CL Datasheet - Page 13

• Manufacturer Part Number: EL1507CL
• Description: IC LINE DRIVER ADSL 16-QFN
• Manufacturer: Intersil
• Type: Driverr

Specifications of EL1507CL

• Number Of Drivers/receivers: 1/0
• Protocol: DSL
• Voltage - Supply: 12V
• Mounting Type: Surface Mount
• Package / Case: 16-VQFN Exposed Pad, 16-HVQFN, 16-SQFN, 16-DHVQFN
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Applications Information
The EL1507 consists of two high-power line driver amplifiers
that can be connected for full duplex differential line
transmission. The amplifiers are designed to be used with
signals up to 4MHz and produce low distortion levels. A
typical interface circuit is shown in Figure 51 below.
The amplifiers are wired with one in positive gain and the
other in a negative gain configuration to generate a
differential output for a single-ended input. They will exhibit
very similar frequency responses for gains of three or
greater and thus generate very small common-mode outputs
over frequency, but for low gains the two drivers R
to be adjusted to give similar frequency responses. The
positive-gain driver will generally exhibit more bandwidth and
peaking than the negative-gain driver.
If a differential signal is available to the drive amplifiers, they
may be wired so:
Each amplifier has identical positive gain connections, and
optimum common-mode rejection occurs. Further, DC input
errors are duplicated and create common-mode rather than
differential line errors.
FIGURE 52. DRIVERS WIRED FOR DIFFERENTIAL INPUT
RECEIVE
RECEIVE
DRIVER
FIGURE 51. TYPICAL LINE INTERFACE CONNECTION
INPUT
OUT +
OUT -
AMPLIFIERS
RECEIVE
R
G
2R
+
+
-
-
R
R
R
R
G
+
+
-
-
F
F
F
F
+
+
-
-
13
R
R
R
R
R
R
F
F
IN
IN
R
OUT
R
OUT
LINE +
LINE -
F
's need
Z
LINE
EL1507
Input Connections
The EL1507 amplifiers are somewhat sensitive to source
impedance. In particular, they do not like being driven by
inductive sources. More than 100nH of source impedance
can cause ringing or even oscillations. This inductance is
equivalent to about 4” of unshielded wiring, or 6” of
unterminated transmission line. Normal high-frequency
construction obviates any such problem.
Power Supplies & Dissipation
Due to the high power drive capability of the EL1507, much
attention needs to be paid to power dissipation. The power
that needs to be dissipated in the EL1507 has two main
contributors. The first is the quiescent current dissipation.
The second is the dissipation of the output stage.
The quiescent power in the EL1507 is not constant with
varying outputs. In reality, 7mA of the 15mA needed to
power the drivers is converted in to output current.
Therefore, in the equation below we should subtract the
average output current, I
We’ll call this term I
Therefore, we can determine a quiescent current with the
equation:
where:
The dissipation in the output stage has two main
contributors. Firstly, we have the average voltage drop
across the output transistor and secondly, the average
output current. For minimal power dissipation, the user
should select the supply voltage and the line transformer
ratio accordingly. The supply voltage should be kept as low
as possible, while the transformer ratio should be selected
so that the peak voltage required from the EL1507 is close to
the maximum available output swing. There is a trade off,
however, with the selection of transformer ratio. As the ratio
is increased, the receive signal available to the receivers is
reduced.
Once the user has selected the transformer ratio, the
dissipation in the output stages can be selected with the
following equation:
where:
V
I
I
V
V
I
S
X
O
S
S
O
is the maximum quiescent supply current (I
is the lesser of I
is the average output current per channel
is the supply voltage (V
is the supply voltage (V
is the average output voltage per channel
P
Dtransistors
P
Dquiescent
X
O
.
or 7mA (generally I
O
, or 7mA, whichever is the lowest.
=
=
S
S
2
+ to V
+ to V
V
×
S
I
O
×
×
(
I
S
S
⎛
⎝
S
V
------ -
-)
-)
2
–
S
2I
–
X
X
V
)
O
= 7mA)
⎞
⎠
S
+ + I
March 26, 2007
FN7013.3
S
-)