TC429

DS21416C-page 10

 2003 Microchip Technology Inc.

The device capacitive load dissipation is:

EQUATION

Quiescent power dissipation depends on input signal

duty cycle. A logic low input results in a low-power

dissipation mode with only 0.5 mA total current drain.

Logic-high signals raise the current to 5 mA maximum.

The quiescent power dissipation is:

EQUATION

Transition power dissipation arises because the output

stage N- and P-channel MOS transistors are ON

simultaneously for a very short period when the output

changes.

The device transition power dissipation is approxi-

mately:

EQUATION

An example shows the relative magnitude for each

item.

TABLE 4-1:

MAXIMUM OPERATING

FREQUENCIES

FIGURE 4-5:

Peak Output Current

Capability.

4.5

POWER-ON OSCILLATION

Power-on oscillations are due to trace size, layout and

component placement. A ‘quick fix’ for most applica-

tions that exhibit power-on oscillation problems is to

place approximately 10 k

Ω in series with the input of

the MOSFET driver.

C

= 2500 pF

= 15V

D

= 50%

f

= 200 kHz

= Package power dissipation:

= 113 mW + 10 mW + 41 mW

= 164 mW

Maximum ambient operating temperature:

= 150ºC - (150ºC/W)(0.164W)

= 125

°C

Where:

= Maximum allowable junction temperature

(+150

°C)

= Junction-to-ambient thermal resistance

(150

°C/W, CERDIP)

PC

fCVS

2

=

Where:

f = Switching frequency

C = Capacitive load

PQ VS DIH

()

1D

–

()IL

+

()

=

Where:

D = Duty cycle

(5 mA max)

(0.5 mA max)

PT fVS 3.3 10

9

–

ASec

•

×





=

Note:

Ambient operating temperature should not

exceed +85ºC for EPA or EOA devices or

+125ºC for MJA devices.

18V

500 kHz

15V

700 kHz

10V

1.3 MHz

5V

>2 MHz

Conditions:

1.

CERDIP Package (

2.

3.

Note:

It is extremely important that all MOSFET

driver applications be evaluated for the

possibility of having high-power oscillations

occur during the power-on cycle.

TIME (5

µs/DIV)

5V

INPUT

OUTPUT

5

µs

500mV

5V/DIV

500mV/DIV

(5 AMP/DIV)