8

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).

In the above example, if the supplies were split ±6V and

the 150

Ω 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 820

Ω resistor to the nega-

tive supply, in a gain of 2 configuration. Driving 75

Ω

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 820

Ω resistor to 500Ω 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 150

Ω. 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.

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 5k

Ω 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.