MIC4424 Micrel Semiconductor, MIC4424 Datasheet - Page 10

• Manufacturer Part Number: MIC4424
• Description: Dual 3A-Peak Low-Side MOSFET Driver Bipolar/CMOS/DMOS Process
• Manufacturer: Micrel Semiconductor

MIC4423/4424/4425
Total power dissipation, then, is:
Assuming an SOIC package, with an
result in the junction running at:
above ambient, which, given a maximum ambient temperature
of 60 C, will result in a maximum junction temperature of
89.4 C.
EXAMPLE 2: A MIC4424 operating on a 15V input, with one
driver driving a 50 resistive load at 1MHz, with a duty cycle
of 67%, and the other driver quiescent, in a maximum ambient
temperature of 40 C:
First, I
Given R
and:
(because only one side is operating)
and:
(this assumes that the unused side of the driver has its input
grounded, which is more efficient)
then:
MIC4423/4424/4425
O
P
P
P
0.2454 x 120 = 29.4 C
P
I
I
P
= (1,000,000 x 15 x 3.3 x 10
= 0.025 W
P
= 0.015W
O
I
must be determined.
O
O
O
D
D
T
L
L
Q
from the characteristic curves then,
= V
= 15 / (3.3 + 50)
= 0.281A
= I
= 15 x [(0.67 x 0.00125) + (0.33 x 0.000125) +
= 12 x [(0.5 x 0.0035) + (0.5 x 0.0003)]
= 0.0228W
= 0.2160 + 0.0066 + 0.0228
= 0.2454W
= (0.281)
= 0.174W
= F x V
= 0.174 + 0.025 + 0.0150
2
S
(1 x 0.000125)]
x R
/ (R
O
S
O
x D
2
x (A•s)/2
+ R
x 3.3 x 0.67
LOAD
)
–9
JA
) / 2
of 120 C/W, this will
10
In a ceramic package with an
power results in a junction temperature given the maximum
40 C ambient of:
The actual junction temperature will be lower than calculated
both because duty cycle is less than 100% and because the
graph lists R
T
Definitions
J
P
P
C
P
P
I
I
R
V
will be somewhat lower.
D = Duty Cycle expressed as the fraction of time the input
I
Q
H
D
D
T
L
L
L
f = Operating Frequency of the driver in Hertz
S
O
= Load Capacitance in Farads.
= Power supply current drawn by a driver when both
= Power supply current drawn by a driver when both
= Output current from a driver in Amps.
= Total power dissipated in a driver in Watts.
= Power dissipated in the driver due to the driver’s load
= Power dissipated in a quiescent driver in Watts.
= Power dissipated in a driver when the output changes
= Power supply voltage to the IC in Volts.
= Output resistance of a driver in Ohms.
(0.213 x 100) + 40 = 61.4 C
to the driver is high.
inputs are high and neither output is loaded.
states (“shoot-through current”) in Watts. NOTE: The
“shoot-through” current from a dual transition (once
up, once down) for both drivers is stated in the graph
on the following page in ampere-nanoseconds. This
figure must be multiplied by the number of repetitions
per second (frequency to find Watts).
inputs are low and neither output is loaded.
in Watts.
DS(on)
= 0.213W
at a T
J
of 125 C and the R
JA
of 100 C/W, this amount of
DS(on)
January 1999
at 61 C
Micrel