EL5367IU-T13 데이터 시트보기 (PDF) - Renesas Electronics
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EL5367IU-T13 Datasheet PDF : 11 Pages
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EL5367
Supply Voltage Range and Single-Supply
Operation
The EL5367 has been designed to operate with supply
voltages having a span of greater than 5V and less than 10V.
In practical terms, this means that the EL5367 will operate
on dual supplies ranging from ±2.5V to ±5V. With single-
supply, they will operate from 5V to 10V.
As supply voltages continue to decrease, it becomes
necessary to provide input and output voltage ranges that
can get as close as possible to the supply voltages. The
EL5367 has an input range which extends to within 1.8V of
either supply. So, for example, on ±5V supplies, the EL5367
has an input range which spans ±3.2V. The output range of
the EL5367 is also quite large, extending to within 1V of the
supply rail. On a ±5V supply, the output is therefore capable
of swinging from -4V to +4V.
Video Performance
For good video performance, an amplifier is required to
maintain the same output impedance and the same
frequency response as DC levels are changed at the
output. This is especially difficult when driving a standard
video load of 150, because of the change in output
current with DC level. Previously, good differential gain
could only be achieved by running high idle currents
through the output transistors (to reduce variations in
output impedance.) These currents were typically
comparable to the entire 8.5mA supply current of each
EL5367 amplifier. Special circuitry has been incorporated in
the EL5367 to reduce the variation of output impedance
with current output. This results in dG and dP specifications
of 0.01% and 0.03°, while driving 150 at a gain of 2.
Output Drive Capability
In spite of the low 8.5mA of supply current, the EL5367 is
capable of providing a minimum of ±110mA of output
current. With so much output drive, the EL5367 is capable of
driving 50 loads to both rails, making it an excellent choice
for driving isolation transformers in telecommunications
applications.
Driving Cables and Capacitive Loads
When used as a cable driver, double termination is always
recommended for reflection-free performance. For those
applications, the back-termination series resistor will
decouple the EL5367 from the cable and allow extensive
capacitive drive. However, other applications may have high
capacitive loads without a back-termination resistor. In these
applications, a small series resistor (usually between 5 and
50) can be placed in series with the output to eliminate
most peaking. The gain resistor (RG) can then be chosen to
make up for any gain loss which may be created by this
additional resistor at the output. In many cases it is also
possible to simply increase the value of the feedback
resistor (RF) to reduce the peaking.
FN7457 Rev 1.00
November 9, 2004
Current Limiting
The EL5367 has no internal current-limiting circuitry. If the
output is shorted, it is possible to exceed the Absolute
Maximum Rating for output current or power dissipation,
potentially resulting in the destruction of the device.
Power Dissipation
With the high output drive capability of the EL5367, it is
possible to exceed the 125°C Absolute Maximum junction
temperature under certain very high load current conditions.
Generally speaking when RL falls below about 25, it is
important to calculate the maximum junction temperature
(TJMAX) for the application to determine if power supply
voltages, load conditions, or package type need to be
modified for the EL5367 to remain in the safe operating area.
These parameters are calculated as follows:
TJMAX = TMAX + JA n PDMAX
where:
TMAX = Maximum ambient temperature
JA = Thermal resistance of the package
n = Number of amplifiers in the package
PDMAX = Maximum power dissipation of each amplifier in
the package
PDMAX for each amplifier can be calculated as follows:
PDMAX = 2 VS ISMAX + VS – VOUTMAX V-----O----U--R--T---L-M-----A----X--
where:
VS = Supply voltage
ISMAX = Maximum supply current of 1A
VOUTMAX = Maximum output voltage (required)
RL = Load resistance
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