4

Typical Performance Curves

Simplified Block Diagram

Applications Information

Product Description

The EL2111 operational amplifier is stable at a gain of 1. It is

built on Elantec’s proprietary complimentary bipolar process.

This topology allows it to be used in a variety of applications

where current mode amplifiers are not appropriate because

of restrictions placed on the feedback elements. This product

is especially designed for applications where high bandwidth

and good video performance characteristics are desired but

the higher cost of more flexible and sophisticated products

are prohibitive.

Power Supplies

The EL2111 is designed to work at a supply voltage

difference of 4.5V to 5.5V. It will work on any combination of

± supplies. All electrical characteristics are measured with a

5V supply.

Output Swing vs Load

Please refer to the simplified block diagram. This amplifier

provides an NPN pull-up transistor output and a passive

1250

Ω pull-down resistor to the most negative supply. In a

Output Drive Capability

This device does not have short circuit protection. Each

output is capable of than 100mA into a shorted output. Care

must be used in the design to limit the output current with a

series resistor.

Single 5V Supply Video Cable Driver

These amplifiers may be used as a direct coupled video

cable driver with a gain of 2. With a 75

Ω back matching

resistor driving a terminated 75

Ω cable the output at the

cable load will be original video level (1V NTSC). The best

operating mode is with direct coupling. The input signal must

be offset to keep the entire signal within the range of the

amplifier. The required offset voltage can be set with a

resistor divider and a bypass capacitor in the video path

(Figure 1). The input DC offset should be between 0.3V and

0.32V. Since these amplifiers require a DC load at their

outputs it is good design practice to add a 250

Ω resistor to

ground directly at the amplifier output. Then if the 75

Ω cable

termination resistor were inadvertently removed there would

still be an output signal. The values in Figure 1 give an

output range of 0V to 2.6V.

Output capacitive coupling also has some restrictions. These

amplifiers require a DC load at their outputs. A 75

Ω back

8-Pin Plastic DIP

Maximum Power Dissipation

vs Ambient Temperature

8-Pin SO

Maximum Power Dissipation

vs Ambient Temperature

5-Pin SOT23

Maximum Power Dissipation

vs Ambient Temperature

EL2111