
EL5164, EL5165, EL5364
11
FN7389.9
January 30, 2014
Output Drive Capability
In spite of their low 3.5mA of supply current, the EL5164, EL5165,
and EL5364 are capable of providing a minimum of ±100mA of
output current. With a minimum of ±100mA of output drive, the
EL5164, EL5165, and EL5364 are capable of driving 50
Ω 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 EL5164, EL5165, and EL5364 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 resistor (usually between 5
Ω and
50
Ω) 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 EL5164, EL5165, and EL5364 have no internal output
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 EL5164, EL5165, and
EL5364, 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 25Ω, 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 to remain
in the safe operating area. These parameters are calculated in
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 in Equation 2: where:
VS = Supply voltage
ISMAX = Maximum supply current of 4.2mA
VOUTMAX = Maximum output voltage (required)
RL = Load resistance
Typical Application Circuits
T
JMAX
T
MAX
θ
JA
nPD
MAX
×
()
+
=
(EQ. 1)
PD
MAX
2
(
V
S
I
SMAX )
V
S
(
V
OUTMAX )
V
OUTMAX
R
L
----------------------------
×
–
+
×
=
(EQ. 2)
FIGURE 25. FAST-SETTLING PRECISION AMPLIFIER
IN+
IN-
VS+
VS-
OUT
IN+
IN-
VS+
VS-
OUT
0.1F
+5V
0.1F
-5V
375
Ω
5
Ω
5
Ω
375
Ω
375
Ω
VOUT
VIN
0.1F
+5V
-5V
FIGURE 24. INVERTING 200mA OUTPUT CURRENT DISTRIBUTION
AMPLIFIER
IN+
IN-
VS+
VS-
OUT
IN+
IN-
VS+
VS-
OUT
0.1F
+5V
0.1F
-5V
0.1F
375
Ω
375
Ω
375
Ω
375
Ω
VOUT
VIN
+5V
-5V