9

FN7288.3

January 3, 2005

Block Diagram

Applications Information

Product Description

The EL7457 is a high performance 40MHz high speed quad

driver. Each channel of the EL7457 consists of a single P-

channel high side driver and a single N-channel low side

driver. These 3

that there is only one set of high and low voltage pins.

A common output enable (OE) pin is available on the

EL7457. This pin, when pulled low will put all outputs in to

the high impedance state.

The EL7457 is available in 16-pin SO (0.150"), 16-pin

QSOP, and ultra-small 16-pin QFN packages. The relevant

package should be chosen depending on the calculated

power dissipation.

Supply Voltage Range and Input Compatibility

The EL7457 is designed for operation on supplies from 5V to

15V with 10% tolerance (i.e. 4.5V to 18V). The table on page

6 shows the specifications for the relationship between the

All input pins are compatible with both 3V and 5V CMOS

also compatible with TTL inputs.

Power Supply Bypassing

When using the EL7457, it is very important to use adequate

power supply bypassing. The high switching currents

developed by the EL7457 necessitate the use of a bypass

capacitor on both the positive and negative supplies. It is

recommended that a 4.7µF tantalum capacitor be used in

parallel with a 0.1µF low-inductance ceramic MLC capacitor.

These should be placed as close to the supply pins as

have some level of bypassing, especially if the EL7457 is

driving highly capacitive loads.

Power Dissipation Calculation

When switching at high speeds, or driving heavy loads, the

EL7457 drive capability is limited by the rise in die

temperature brought about by internal power dissipation. For

reliable operation die temperature must be kept below

dissipation for a given application prior to selecting package

type.

Power dissipation may be calculated:

where:

f is frequency

Having obtained the application’s power dissipation, the

maximum junction temperature can be calculated:

where:

PD is the power dissipation calculated above

application (package + PCB combination). Refer to the

Package Power Dissipation curves on page 6.

3-STATE

CONTROL

LEVEL

SHIFTER

OUTPUT

OE

INPUT

GND

PD

×

()

2

×

f

×

()

2

×

f

×

()

+

1

4

∑

+

=

×

+

=

EL7457