EL5160, EL5161, EL5260, EL5261, EL5360
10
FN7387.10
January 30, 2014
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 EL5160, EL5161, EL5260, EL5261, and EL5360 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.
Current Limiting
The EL5160, EL5161, EL5260, EL5261, and EL5360 have 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 EL5160, EL5161,
EL5260, EL5261, and EL5360, 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 EL5160, EL5161, EL5260, EL5261, and
EL5360 to remain in the safe operating area. These parameters
are calculated as follows:
where:
TMAX = Maximum ambient temperature
θJA = 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:
where:
VS = Supply voltage
ISMAX = Maximum supply current of 0.85mA
VOUTMAX = Maximum output voltage (required)
RL = Load resistance
Typical Application Circuits
T
JMAX
T
MAX
θ
JA
nPD
MAX
×
()
+
=
PD
MAX
2
(
V
S
I
SMAX )
V
S
(
V
OUTMAX )
V
OUTMAX
R
L
----------------------------
×
–
+
×
=
IN+
IN-
VS+
VS-
OUT
IN+
IN-
VS+
VS-
OUT
0.1F
+5V
0.1F
-5V
500
5
500
VOUT
VIN
0.1F
+5V
-5V
FIGURE 21. INVERTING 200mA OUTPUT CURRENT DISTRIBUTION
AMPLIFIER
IN+
IN-
VS+
VS-
OUT
IN+
IN-
VS+
VS-
OUT
0.1F
+5V
0.1F
-5V
0.1F
500
VOUT
VIN
+5V
-5V
FIGURE 22. FAST-SETTLING PRECISION AMPLIFIER