EL1509CS-T7 Intersil, EL1509CS-T7 Datasheet - Page 8

• Manufacturer Part Number: EL1509CS-T7
• Description: IC LINE DRIVER CPE ADSL 8-SOIC
• Manufacturer: Intersil
• Type: Driverr

Specifications of EL1509CS-T7

• Number Of Drivers/receivers: 1/0
• Voltage - Supply: 5 V ~ 12 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Protocol: -

Capacitance at the Inverting Input
Due to the topology of the current feedback amplifier, stray
capacitance at the inverting input will affect the AC and
transient performance of the EL1509 when operating in the
non-inverting configuration.
In the inverting gain mode, added capacitance at the
inverting input has little effect since this point is at a virtual
ground and stray capacitance is therefore not “seen” by the
amplifier.
Feedback Resistor Values
The EL1509 has been designed and specified with R
1.5kΩ for A
extremely flat frequency response with little to no peaking
out to 50MHz. As is the case with all current feedback
amplifiers, wider bandwidth, at the expense of slight
peaking, can be obtained by reducing the value of the
feedback resistor. Inversely, larger values of feedback
resistor will cause rolloff to occur at a lower frequency. See
the curves in the Typical Performance Curves section which
show 3dB bandwidth and peaking vs. frequency for various
feedback resistors and various supply voltages.
Bandwidth vs Temperature
Whereas many amplifier's supply current and consequently
3dB bandwidth drop off at high temperature, the EL1509 was
designed to have little supply current variations with
temperature. An immediate benefit from this is that the 3dB
bandwidth does not drop off drastically with temperature.
V
= +5. This value of feedback resistor yields
8
AFE
464Ω
+
+
-
1.5k
-
1.5k
F
=
EL1509
12.5
12.5
Supply Voltage Range
The EL1509 has been designed to operate with supply
voltages from ±2.5V to ±6V. Optimum bandwidth, slew rate,
and video characteristics are obtained at higher supply
voltages. However, at ±2.5V supplies, the 3dB bandwidth at
A
Single Supply Operation
If a single supply is desired, values from +5V to +12V can be
used as long as the input common mode range is not
exceeded. When using a single supply, be sure to either 1)
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 EL1509.
ADSL CPE Applications
The EL1509 is designed as a line driver for ADSL CPE
modems. It is capable of outputting 250mA of output current
with a typical supply voltage headroom of 1.3V. It can
achieve -85dBc of distortion at low 7.1mA of supply current
per amplifier.
The average line power requirement for the ADSL CPE
application is 13dBm (20mW) into a 100Ω line. The average
line voltage is 1.41V
ratio (crest factor) of 5.3 implies peak voltage of 7.5V into the
line. Using a differential drive configuration and transformer
coupling with standard back termination, a transformer ratio
of 1:2 is selected. The circuit configuration is as shown
below.
V
= +2 is a respectable 40MHz.
TX1
1:2
RMS
. The ADSL DMT peak to average
100
March 26, 2007
FN7015.2