11

FN7176.1

November 19, 2004

Applications Information

Product Description

The EL5123, EL5223, EL5323, and EL5423 unity gain

buffers are fabricated using a high voltage CMOS process. It

exhibits rail-to-rail input and output capability and has low

power consumption (600µA per buffer). These features

make the EL5123, EL5223, EL5323, and EL5423 ideal for a

wide range of general-purpose applications. When driving a

load of 10k

Ω and 12pF, the EL5123, EL5223, EL5323, and

EL5423 have a -3dB bandwidth of 12MHz and exhibits

15V/µs slew rate.

Operating Voltage, Input, and Output

The EL5123, EL5223, EL5323, and EL5423 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

EL5123, EL5223, EL5323, and EL5423 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 output swings of the EL5123, EL5223, EL5323, and

EL5423 typically extend to within 50mV 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 24shows the input and

output waveforms for the device. Operation is from ±5V

supply with a 10k

Ω load connected to GND. The input is a

FIGURE 24. OPERATION WITH RAIL-TO-RAIL INPUT AND

OUTPUT

Short Circuit Current Limit

The EL5123, EL5223, EL5323, and EL5423 will limit the

short circuit current to ±120mA 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 ±30mA. This limit is set by the design of the internal

metal interconnects.

Output Phase Reversal

The EL5123, EL5223, EL5323, and EL5423 are immune to

phase reversal as long as the input voltage is limited from

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 over-voltage 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 over-voltage damage could

occur.

FIGURE 25. OPERATION WITH BEYOND-THE-RAILS INPUT

Power Dissipation

With the high-output drive capability of the EL5123, EL5223,

EL5323, and EL5423 buffer, 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 buffer 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

1V

1V

10µs

–

Θ

---------------------------------------------

=

ΣiV

[

S

(

×

–

+

×

=

EL5123, EL5223, EL5323, EL5423