EL5129 데이터 시트보기 (PDF) - Intersil

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EL5129

Multi-Channel Buffers

Intersil 

EL5129, EL5329

Description of Operation and Application

Information

Product Description

The EL5129 and EL5329 are fabricated using a high voltage

CMOS process. They exhibit rail to rail input and output

capability and have very low power consumption. When

driving a load of 10K and 12pF, the buffers have a

-3dB bandwidth of 10MHz and exhibit 9V/µs slew rate. The

VCOM amplifier has a -3dB bandwidth of 12MHz and exhibit

10V/µs slew rate.

Input, Output, and Supply Voltage Range

The EL5129 and EL5329 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 from 4.5V to 16.5V.

The input common-mode voltage range of the EL5129 and

EL5329 within 500mV beyond the supply rails. The output

swings of the buffers and VCOM amplifier typically extend to

within 100mV of the positive and negative supply rails with

load currents of 5mA. Decreasing load currents will extend

the output voltage even closer to each supply rails.

Output Phase Reversal

The EL5129 and EL5329 are immune to phase reversal as

long as the input voltage is limited from VS- -0.5V to VS+

+0.5V. 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 diode placed in the input stage of the

device begin to conduct and over-voltage damage could

occur.

Output Drive Capability

The EL5129 and EL5329 do not have internal short-circuit

protection circuitry. The buffers will limit the short circuit

current to ±120mA and the VCOM amplifier will limit the short

circuit current to ±170mA if the outputs are directly shorted

to the positive or the negative supply. If the output is shorted

indefinitely, the power dissipation could easily increase such

that the part will be destroyed. Maximum reliability is

maintained if the output continuous current never exceeds

±15mA for the buffers and ±100mA for the VCOM amplifier.

These limits are set by the design of the internal metal

interconnections.

The Unused Buffers

It is recommended that any unused buffers should have their

inputs tied to ground plane.

Power Dissipation

With the high-output drive capability of the EL5129 and

EL5329, 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:

PDMAX

=

T----J---M-----A----X-----------T----A----M----A----X--

ΘJA

where:

• TJMAX = Maximum junction temperature

• TAMAX = Maximum ambient temperature

• θJA = Thermal resistance of the package

• PDMAX = Maximum power dissipation in the package

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:

PDMAX = VS × IS + Σi × [(VS+ – VOUTi ) × ILOADi ] +

(VS+ – VOUT ) × ILA

when sourcing, and:

PDMAX = VS × IS + Σi × [(VOUTi – VS- ) × ILOADi ] +

(VOUT – VS- ) × ILA

when sinking.

where:

• i = 1 to total number of buffers

• VS = Total supply voltage of buffer and VCOM

• ISMAX = Total quiescent current

• VOUTi = Maximum output voltage of the application

• VOUT = Maximum output voltage of VCOM

• ILOADi = Load current of buffer

• ILA = Load current of VCOM

If we set the two PDMAX equations equal to each other, we

can solve for the RLOAD's to avoid device overheat. The

package power dissipation curves provide a convenient way

to see if the device will overheat. The maximum safe power

dissipation can be found graphically, based on the package

type and the ambient temperature. By using the previous

equation, it is a simple matter to see if PDMAX exceeds the

device's power derating curves.

10

FN7430.1

May 13, 2005

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