mic94044 Micrel Semiconductor, mic94044 Datasheet - Page 7

• Manufacturer Part Number: mic94044
• Description: 28m? Rdson 3a High Side Load Switch In 1.2mm X 1.2mm Mlf Package
• Manufacturer: Micrel Semiconductor

Example:
A switch is intended to drive a 2A load and is placed on
a printed circuit board which has a ground plane area of
at least 25mm x 25mm (625mm
a Li-ion battery with a lower operating threshold of 3V
and the ambient temperature of the assembly can be up
to 50
Micrel, Inc.
March 2011
o
C.
Figure 4: Excerpt from the LDO Book
2
). The Voltage source is
7
Summary of variables:
The worst case switch resistance (R
V
lower value of V
If this were a figure for worst case R
additional consideration is to allow for the maximum
junction temperature of 125
resistance in this case can be 30% higher (See R
variance vs. temperature graph). However, 90mΩ is the
maximum over temperature.
Therefore:
This is below the maximum 125
IN
of 3V is not available in the datasheet, so the next
I
V
T
Rθ
Rθ
P
R
T
T
SW
A
J
J
IN
DISS
SWmax
= 2
= 101
JC
CA
= 50
= 2A
= 3V to 4.2V
= 90
= 53
= I
2
o
@ 2.5V = 90mΩ
x 0.090 x (90+53) + 50
IN
SW
C
o
C
o
o
is used.
C/W from Datasheet
2
C/W Read from Graph in Figure 4
x R
SWmax
o
C, the actual worst case
o
C.
SWmax
SWmax
M9999-032311-A
) at the lowest
MIC94044/5
for 25
o
C, an
DSON