MIC2017 Micrel Semiconductor, MIC2017 Datasheet - Page 16

• Manufacturer Part Number: MIC2017
• Description: (MIC2007 / MIC2017) Adjustable Current Limit Power Distribution Switch
• Manufacturer: Micrel Semiconductor

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Micrel
equation can be used:
Where: T
In normal operation, the MIC2007/2017’s R
enough that no significant I
heating is most often caused by a short circuit — or very
heavy load — when a significant portion of the input
supply voltage appears across the MIC2007/2017’s
power MOSFET. Under these conditions, the heat
generated will exceed the package and PCB’s ability to
cool the device and thermal limiting will be invoked.
In Figure 10, die temperature is plotted against I
assuming a constant case temperature of 85°C. The
plots also assume a worst case R
temperature of 135°C. Under these conditions, it is clear
that an SOT-23 packaged device will be on the verge of
thermal shutdown (typically 145°C die temperature)
when operating at a load current of 1.25A. For this
reason, it is recommend that MLF package be used for
any
continuous currents of 1A or more.
Figure 10 assumes no backside contact is made to the
thermal pad provided on the MLF package. For optimal
October 2005
T
R
T
A
θ (J-A)
J
MIC2007/2017
= ambient temperature
=
160
140
120
100
80
60
40
20
Figure 10. Die Temperature vs. Package
J
P
0
is the thermal resistance of the package
= junction temperature,
0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
D
Die Temperature vs. Iout for Tcase = 85°C
×
R
θ
(J
-
A)
+
designs
T
A
Iout - Amps
2
R heating occurs. Device
intending
ON
of 140 mΩ at a die
SOT-23
MLF
to
on
is low
supply
OUT
16
performance at higher current levels, or in higher
temperature environments, thermal contact with the
PCB and the exposed power paddle on the back side of
the MLF package should be made. This significantly
reduces the package’s thermal resistance thereby
extending the MIC2007/2017’s operating range. It
should be noted that this backside paddle is electrically
active and is connected to the MIC2007/2017’s GND
pin.
Figure 11. Pad for Thermal Mounting to PCB
to Ground Plane
0.3 mm diam.
2 Vias
0.8 mm
MIC2007/MIC2017
1.4 mm
M9999-102805