MIC2004 Micrel, MIC2004 Datasheet - Page 13

• Manufacturer Part Number: MIC2004
• Description: Fixed Current Limit Power Distribution Switch
• Manufacturer: Micrel

August 2005
Micrel
Application Information
I
MIC2004/2014’s’s current limiting circuitry is designed to
act as a constant current source to the load. As the load
tries to pull more than the allotted current, V
and the input to output voltage differential increases.
When V
reduce the drain of fault current on the system’s power
supply and to limit internal heating of MIC2004/2014.
When measuring I
dependence in mind, otherwise the measurement data
may appear to indicate a problem when none really
exists. This voltage dependence is illustrated in Figures
4 and 5.
In Figure 4 output current is measured as V
below V
below V
remains constant throughout the remainder of the test.
In Figure 5 this test is repeated but with V
exceeding 1V.
When V
circuitry responds by decreasing I
Figure 5. In this demonstration, V
and I
applications V
Ohm’s law by the load and the limiting current.
LIMIT
Figure 4. I
vs. I
OUT
IN
IN
IN
IN
OUT
, with the test terminating when V
.
-V
- V
is the measured quantity. In real life
OUT
OUT
measured
Observe that once I
OUT
OUT
in Current Limiting for V
exceeds 1V, I
> 1V, MIC2004/2014’s current limiting
OUT
is determined in accordance with
it is important to bear this voltage
OUT
OUT
OUT
LIMIT
drops below I
, as can be seen in
is being controlled
is reached I
IN
- V
OUT
OUT
OUT
OUT
IN
is pulled
LIMIT
- V
≤1V
drops
is 1V
OUT
OUT
to
13
This folding back of I
I
of V
1) is determined by R
LIMIT
Figure 5. I
OUT
as a function of V
between I
1.2
1.0
0.8
0.6
0.4
0.2
OUT
0
0
Normalized Output Current
in Current Limiting for V
OUT
vs. Output Voltage (5V)
OUTPUT VOLTAGE (V)
1
LIMIT
= 0 and I
ON
OUT
Figure 6.
of MIC2004/2014 and I
2
can be generalized by plotting
, as shown below. The slope
3
OUT
= I
4
LIMIT
MIC2004/MIC2014
www.DataSheet4U.com
5
(where I
IN
[phone]
M9999-080305
- V
6
LIMIT
OUT
LIMIT
>1V
.
=