11

FN7355.1

August 3, 2005

Applications Information

Product Description

The EL5611 and EL5811 voltage feedback amplifiers are

fabricated using a high voltage CMOS process. They exhibit

rail-to-rail input and output capability, are unity gain stable

and have low power consumption (2.5mA per amplifier).

These features make the EL5611, and EL5811 ideal for a

wide range of general-purpose applications. Connected in

voltage follower mode and driving a load of 1k

Ω, the EL5611

and EL5811 have a -3dB bandwidth of 60MHz while

maintaining a 75V/µs slew rate. The EL5611 a six channel

amplifier, and the EL5811 an 8 channel amplifier.

Operating Voltage, Input, and Output

The EL5611and EL5811 are specified with a single nominal

supply voltage from 5V to 15V or a split supply with its total

range from 5V to 15V. Correct operation is guaranteed for a

supply range of 4.5V to 16.5V. Most EL5611 and EL5811

specifications are stable over both the full supply range and

operating temperatures of -40°C to +85°C. Parameter

variations with operating voltage and/or temperature are

shown in the typical performance curves.

The input common-mode voltage range of the EL5611 and

EL5811 extends 500mV beyond the supply rails. The output

swings of the EL5611 and EL5811 typically extend to within

100mV of positive and negative supply rails with load

currents of 5mA. Decreasing load currents will extend the

output voltage range even closer to the supply rails. Figure

27 shows the input and output waveforms for the device in

the unity-gain configuration. Operation is from ±5V supply

with a 1k

Short Circuit Current Limit

The EL5611 and EL5811 will limit the short circuit current to

±180mA if the output is directly shorted to the positive or the

negative supply. If an output is shorted indefinitely, the power

dissipation could easily increase such that the device may

be damaged. Maximum reliability is maintained if the output

continuous current never exceeds ±65mA. This limit is set by

the design of the internal metal interconnects.

Output Phase Reversal

The EL5611 and EL5811 are immune to phase reversal as

+0.5V. Figure 28 shows a photo of the output of the device

with the input voltage driven beyond the supply rails.

Although the device's output will not change phase, the

input's overvoltage should be avoided. If an input voltage

exceeds supply voltage by more than 0.6V, electrostatic

protection diodes placed in the input stage of the device

begin to conduct and overvoltage damage could occur.

Power Dissipation

With the high-output drive capability of the EL5611 and

EL5811 amplifiers, it is possible to exceed the 125°C

'absolute-maximum junction temperature' under certain load

current conditions. Therefore, it is important to calculate the

maximum junction temperature for the application to

determine if load conditions need to be modified for the

amplifier to remain in the safe operating area.

The maximum power dissipation allowed in a package is

determined according to:

where:

•

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 loads, or:

5V

5V

10µs

FIGURE 27. OPERATION WITH RAIL-TO-RAIL INPUT AND

OUTPUT

1V

1V

10µs

FIGURE 28. OPERATION WITH BEYOND-THE-RAILS INPUT

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EL5611, EL5811