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EL2245C, EL2445C

Dual/Quad Low-Power 100MHz Gain-of-2 Stable Op Amp

Applications Information

Product Description

The EL2245C/EL2445C are dual and quad low-power

wideband monolithic operational amplifiers built on

Elantec's proprietary high-speed complementary bipolar

process. The EL2245C/EL2445C use a classical volt-

age-feedback topology which allows them to be used in

a variety of applications where current-feedback ampli-

fiers are not appropriate because of restrictions placed

upon the feedback element used with the amplifier. The

conventional topology of the EL2245C/EL2445C

allows, for example, a capacitor to be placed in the feed-

back path, making it an excellent choice for applications

such as active filters, sample-and-holds, or integrators.

Similarly, because of the ability to use diodes in the

feedback network, the EL2245C/EL2445C are an excel-

lent choice for applications such as fast log amplifiers.

Power Dissipation

With the wide power supply range and large output drive

capability of the EL2245C/EL2445C, it is possible to

exceed the 150°C maximum junction temperatures

under certain load and power-supply conditions. It is

therefore important to calculate the maximum junction

power supply voltages, load conditions, or package type

need to be modified for the EL2245C/EL2445C to

remain in the safe operating area. These parameters are

related as follows:

where PDmaxtotal is the sum of the maximum power

dissipation of each amplifier in the package (PDmax).

PDmax for each amplifier can be calculated as follows:

where:

PDmax =Maximum Power Dissipation of 1 Amplifier

Application

To serve as a guide for the user, we can calculate maxi-

mum allowable supply voltages for the example of the

ple) that we are driving a back-terminated video cable,

then the maximum average value (over duty-cycle) of

in Table 1.

Single-Supply Operation

The EL2245C/EL2445C have been designed to have a

wide input and output voltage range. This design also

makes the EL2245C/EL2445C an excellent choice for

single-supply operation. Using a single positive supply,

the lower input voltage range is within 100mV of ground

within 300 mV of ground. Upper input voltage range

reaches 4.2V, and output voltage range reaches 3.8V

output swing on a single 5V supply. This wide output

voltage range also allows single-supply operation with a

supply voltage as high as 36V or as low as 2.5V. On a

single 2.5V supply, the EL2245C/EL2445C still have

1V of output swing.

Gain-Bandwidth Product and the -3dB

Bandwidth

The EL2245C/EL2445C have a bandwidth at gain-of-2

of 100MHz while using only 5.2mA of supply current

per amplifier. For gains greater than 4, their closed-loop

-3dB bandwidth is approximately equal to the gain-

Table 1

Duals

Package

EL2245CN

PDIP8

95°C/W

0.789W @ 75°C

±16.6V

EL2245CS

SO8

150°C/W

0.500W @ 75°C

±10.7V

QUADS

EL2445CN

PDIP14

70°C/W

1.071W @ 75°C

±11.5V

EL2445CS

SO14

110°C/W

0.682W @ 75°C

±7.5V