TC429
DS21416D-page 10 2002-2012 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 in series with the input of
the MOSFET driver.
C = 2500 pF
V
S
= 15V
D = 50%
f = 200 kHz
P
D
= Package power dissipation:
= P
C
+ P
T
+ P
Q
= 113 mW + 10 mW + 41 mW
= 164 mW
Maximum ambient operating temperature:
= T
J
–
JA
(P
D
)
= 150ºC - (150ºC/W)(0.164W)
= 125C
Where:
T
J
= Maximum allowable junction temperature
(+150C)
JA
= Junction-to-ambient thermal resistance
(150C/W, CERDIP)
P
C
fCV
S
2
=
Where:
f = Switching frequency
C = Capacitive load
V
S
= Supply voltage
P
Q
V
S
DI
H
1D–I
L
+=
Where:
I
H
= Quiescent current with input high
I
L
= Quiescent current with input low
D = Duty cycle
(5 mA max)
(0.5 mA max)
P
T
fV
S
3.3 10
9–
ASec=
Note: Ambient operating temperature should not
exceed +85ºC for EPA or EOA devices or
+125ºC for MJA devices.
V
S
f
MAX
18V 500 kHz
15V 700 kHz
10V 1.3 MHz
5V >2 MHz
Conditions:
1. CERDIP Package (
JA
=150C/W)
2. T
A
= +25C
3. C
L
= 2500 pF
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 (5μs/DIV)
V
S
= 18V
R
L
= 0.1Ω
5V
INPUT
OUTPUT
5μs
500mV
5V/DIV
500mV/DIV
(5 AMP/DIV)
