EL5174, EL5374
Where:
T
JMAX
= Maximum junction temperature
T
AMAX
= Maximum ambient temperature
θ
JA
= Thermal resistance of the package
The maximum power dissipation actually produced by an IC
is the total quiescent supply current times the total power
supply voltage, plus the power in the IC due to the load, or:
∆V
O
-
PD
=
i
×
V
S
×
I
SMAX
+
V
S
×
-----------
R
LD
Power Supply Bypassing and Printed Circuit
Board Layout
As with any high frequency device, a good printed circuit
board layout is necessary for optimum performance. Lead
lengths should be as sort as possible. The power supply pin
must be well bypassed to reduce the risk of oscillation. For
normal single supply operation, where the V
S
- pin is
connected to the ground plane, a single 4.7µF tantalum
capacitor in parallel with a 0.1µF ceramic capacitor from V
S
+
to GND will suffice. This same capacitor combination should
be placed at each supply pin to ground if split supplies are to
be used. In this case, the V
S
- pin becomes the negative
supply rail.
For good AC performance, parasitic capacitance should be
kept to minimum. Use of wire wound resistors should be
avoided because of their additional series inductance. Use
of sockets should also be avoided if possible. Sockets add
parasitic inductance and capacitance that can result in
compromised performance. Minimizing parasitic capacitance
at the amplifier's inverting input pin is very important. The
feedback resistor should be placed very close to the
inverting input pin. Strip line design techniques are
recommended for the signal traces.
Where:
V
S
= Total supply voltage
I
SMAX
= Maximum quiescent supply current per channel
∆V
O
= Maximum differential output voltage of the
application
R
LD
= Differential load resistance
I
LOAD
= Load current
i = Number of channels
By setting the two PD
MAX
equations equal to each other, we
can solve the output current and R
LD
to avoid the device
overheat.
Typical Applications
R
F
FBP
IN+
R
T
R
G
IN-
REF
FBN
R
F
EL5174/
EL5374
50
TWISTED PAIR
IN+
EL5175/
EL5375
50
Z
O
= 100Ω
IN-
REF
V
O
R
FR
R
GR
FIGURE 25. TWISTED PAIR CABLE RECEIVER
As the signal is transmitted through a cable, the high
frequency signal will be attenuated. One way to compensate
this loss is to boost the high frequency gain at the receiver
side.
12
FN7313.5
August 8, 2005
INTERSIL [ INTERSIL CORPORATION ]
