EL2210C/11C, EL2310C/11C, EL2410C/11C
Low Cost, Dual, Triple and Quad Video Op Amps
EL2211C. The total dual amplifier power dissipation
would be 146mW + 240mW = 386mW, more than the
maximum 361mW allowed. If the total supply differ-
ence were reduced to 10V, the same calculations would
yield 200mW quiescent power dissipation and 120mW
due to loading. This results in a die temperature of
143°C (85°C + 58°C).
Printed-Circuit Layout
The EL2210C/EL2211C/EL2310C/EL2311C/
EL2410C/EL2411C are well behaved, and easy to apply
in most applications. However, a few simple techniques
will help assure rapid, high quality results. As with any
high-frequency device, good PCB layout is necessary
for optimum performance. Ground-plane construction is
highly recommended, as is good power supply bypass-
ing. A 0.1µF ceramic capacitor is recommended for
bypassing both supplies. Lead lengths should be as short
as possible, and bypass capacitors should be as close to
the device pins as possible. For good AC performance,
parasitic capacitances should be kept to a minimum at
both inputs and at the output. Resistor values should be
kept under 5kW because of the RC time constants associ-
ated with the parasitic capacitance. Metal-film and
carbon resistors are both acceptable, use of wire-wound
resistors is not recommended because of their parasitic
inductance. Similarly, capacitors should be low-induc-
tance for best performance.
In the above example, if the supplies were split ±6V and
the 150W loads were connected to ground, the load
induced power dissipation would drop to 66.7mW
(6.67mA * (6 - 1) * 2) and the die temperature would be
below the rated maximum.
Video Performance
Following industry standard practices (see EL2044C
applications section) these six devices exhibit good dif-
ferential gain (dG) and good differential phase (dP) with
±5V supplies and an external 820W resistor to the nega-
tive supply, in a gain of 2 configuration. Driving 75W
back terminated cables to standard video levels (1.428V
at the amplifier) the EL2210C, EL2310C, and EL2410C
have dG of 0.1% and dP of 0.2°. The EL2211C,
EL2311C, and EL2411C have dG of 0.04% and dP of
0.15°.
Due to the negative swing limitations described above,
inverted video at a gain of 2 is just not practical. If
swings below ground are required then changing the
extra 820W resistor to 500W will allow reasonable dG
and dP to approximately -0.75mV. The EL2211C,
EL2311C, and EL2411C will achieve approximately
0.1%/0.4° between 0V and -0.75V. Beyond -0.75V dG
and dP get worse by orders of magnitude.
Differential gain and differential phase are fairly con-
stant for all loads above 150W. Differential phase
performance will improve by a factor of 3 if the supply
voltage is increased to ±6V.
Output Drive Capability
None of these devices have short circuit protection. Each
output is capable of more than 100mA into a shorted
output. Care must be used in the design to limit the out-
put current with a series resistor.
8
ELANTEC [ ELANTEC SEMICONDUCTOR ]
