MIC2003 MICREL [Micrel Semiconductor], MIC2003 Datasheet - Page 15

• Manufacturer Part Number: MIC2003
• Description: Current Limiting Circuit Protector
• Manufacturer: MICREL [Micrel Semiconductor]

October 2005
Where: T
In normal operation MIC2003/2013’s Ron is low enough
that no significant I2R heating occurs. Device heating is
most often caused by a short circuit, or very heavy load,
when a significant portion of the input supply voltage
appears across MIC2003/2013’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 RON of 140 mΩ at a die
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 140°C die temperature,
when operating at a load current of 1.25A. For this
reason
MIC2003/2013s for any design intending to supply
continuous currents of 1A or more.
T
R
A
θ(J-A)
= ambient temperature
160
140
120
100
80
60
40
20
J
0
we
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
Figure 10. Die Temperature vs. I
Die Temperature vs. Iout for Tcase = 85°C
recommend
Iout - Amps
using
MLF
SOT-23
MLF
OUT
packaged
OUT
15
When operating at higher current levels or in higher
temperature
packaging is recommended. MLF packages provide an
exposed power paddle on the back side to which
electrical and thermal contact can be made with the
device. This significantly reduces the package’s thermal
resistance and thus extends the MIC2005/2013’s
operating range.
to Ground Plane
Figure 11. Pad for thermal mounting to PCB
0.3 mm diam.
2 Vias
environments
[e-mail]
0.8 mm
use
of
or [phone]
1.4 mm
Micrel’s
M9999-102605
MLF