MIC4224 MICREL [Micrel Semiconductor], MIC4224 Datasheet - Page 11

• Manufacturer Part Number: MIC4224
• Description: Dual 4A, 4.5V to 18V, 15ns Switch Time, Low-Side MOSFET Drivers with Enable
• Manufacturer: MICREL [Micrel Semiconductor]

Quiescent Current Power Dissipation
Quiescent current powers the internal logic, level shifting
circuitry and bias for the output drivers. This current is
proportional to operating frequency and V
typical characteristic graphs show how supply current
varies with switching frequency and supply voltage.
The power dissipated by the driver’s quiescent current is:
Total Power Dissipation and Thermal Considerations
Total package power dissipation equals the power
dissipation of each driver caused by driving the external
MOSFETs plus the supply current.
The die temperature may be calculated once the total
power dissipation is known.
The following graphs help determine the maximum gate
charge that can be driven with respect to switching
frequency, supply voltage and ambient temperature.
Figure 5a shows the power dissipation in the driver for
different values of gate charge with V
shows the power dissipation at V
the maximum power dissipation for a given ambient
temperature for the SOIC and ePAD MSOP packages.
The maximum operating frequency of the driver may be
limited by the maximum power dissipation of the driver
package.
Micrel, Inc.
June 2009
Where:
T
T
Pdiss
θ
T
Pdiss
Pdiss
JA
A
J
J
ambient air (°C/W)
is the junction temperature (°C)
is the Maximum ambient temperature
=
is the thermal resistance from junction-to-
T
TOTAL
TOTAL
quiescent
A
+
Pdiss
is the power dissipation of the Driver
=
=
Pdiss
V
TOTAL
DD
quiescent
×
I
×
DD
θ
JA
+
Pdriver
DD
= 12V. Figure 5c show
DD
A
= 5V. Figure 5b
+
DD
Pdriver
voltage. The
B
11
Figure 5c. Maximum P
Figure 5b. P
Figure 5a. P
1.4
1.2
1.0
0.8
0.6
0.4
0.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
2.0
1.5
1.0
0.5
0.0
100k
100k
0
0
20
V
V
DD
Ambient Temperature (°C)
PDISS: GATE Charge
DD
PDISS: GATE Charge
DISS
DISS
=12V
40
Maximum Power
=5V
FREQUENCY (Hz)
FREQUENCY (Hz)
vs. Frequency
vs. Frequency
vs. Q
vs. Q
Dissipation
DISS
60
MIC4223/MIC4224/MIC4225
G
G
vs. Ambient Temperature
1M
1M
and f
80
and f
50nC
S
100
S
for V
for V
40nC
120
30nC
20nC
10nC
40nC
30nC
20nC
10nC
50nC
DD
M9999-061109-A
DD
[phone]
10M
10M
= 12V
= 5V
140