MIC2090-1YM5 TR Micrel Inc, MIC2090-1YM5 TR Datasheet - Page 16

• Manufacturer Part Number: MIC2090-1YM5 TR
• Description: IC DISTRIBUTION SW 50MA SOT-23-5
• Manufacturer: Micrel Inc
• Series: -r
• Type: High Side Switchr

Specifications of MIC2090-1YM5 TR

• Number Of Outputs: 1
• Rds (on): 1.2 Ohm
• Internal Switch(s): Yes
• Current Limit: 50mA
• Voltage - Input: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SC-74A, SOT-753
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: 576-3890-2; MIC2090-1YM5TR

Micrel, Inc.
During an overcurrent or short circuit, The FAULT/ signal
asserts after a brief delay period, t
filter out false or transient over-current conditions.
The FAULT/ output is open-drain and must be pulled
HIGH with an external resistor. The FAULT/ signal may
be wire-OR’d with other similar outputs, sharing a single
pull-up resistor.
Power Dissipation and Thermal Shutdown
Thermal
MIC2090/MIC2091 switch from damage should the die
temperature exceed a safe operating temperature.
Thermal shutdown shuts off the output MOSFET and
asserts the FAULT/ output if the die temperature
reaches the over-temperature threshold, T
The switch will automatically resume operation when the
die temperature cools down to 140°C. If resumed
operation results in reheating of the die, another
shutdown cycle will occur and the switch will continue
cycling between ON and OFF states until the reason for
the overcurrent condition has been resolved.
Depending upon the PCB layout, package type, ambient
temperature, etc., hundreds of milliseconds may elapse
from the time a fault occurs to the time the output
MOSFET will be shut off. This delay is caused because
of the time it takes for the die to heat after the fault
condition occurs.
Power dissipation depends on several factors such as
the load, PCB layout, ambient temperature, and supply
voltage. Calculation of power dissipation can be
accomplished by Equation 2:
To relate this to junction temperature, Equation 3 can be
used:
Where:
R
In normal operation, excessive switch heating is most
often caused by an output short circuit. If the output is
shorted,
MIC2090/MIC2091 switch limits the output current to the
maximum value. The heat generated by the power
dissipation of the switch continuously limiting the current
July 2011
θ(J-A)
is the thermal resistance of the package.
P
T
T
T
J
J
A
D
= P
= Junction Temperature
= Ambient Temperature
= R
when
shutdown
D
DS(ON)
× R
θ(J-A)
the
× (I
OUT
+ T
is
)
switch
A
2
used
is
D_FAULT/
to
enabled,
OVERTEMP
protect
, in order to
.
Eq. 3
Eq.2
the
the
16
may exceed the package and PCB’s ability to cool the
device and the MIC2090/MIC2091 will shut down and
signal a fault condition. Please see the “Fault Output”
description for more details on the FAULT/ output.
After the MIC2090/MIC2091 shuts down, and cools, it
will re-start itself if the enable signal remains true.
n Figure 2, die temperature is plotted against I
assuming a constant ambient temperature of 85°C and a
worst case internal switch on-resistance (R
is valid for both the MIC2090 and MIC2091.
I
When the MIC2090/MIC2091 is current limiting, it is
designed to act as a constant current source to the load.
As the load tries to pull more than the maximum current,
V
increases. When V
switch momentarily turns off to insure the internal
MOSFET switch is not damaged by a very fast short
circuit event.
important to remember voltage dependence, otherwise
the measurement data may appear to indicate a problem
when none really exists. This voltage dependence is
illustrated in Figures 3 and 4.
In Figure 3, output current is measured as V
below V
below V
remains constant throughout the remainder of the test.
Figure 4 repeats this test but simulates operation deeper
into an overcurrent condition. When V
1.8V, the switch turns off for a few microseconds before
turning back on.
LIMIT
When measuring I
OUT
vs. I
90
89
88
87
86
85
84
83
drops and the input to output voltage differential
0.01
IN
IN
OUT
, with the test terminating when V
. Observe that once I
Die Temperature vs. Output Current
0.02
Figure 2. Die Temperature vs. I
Measured (-1 version only)
(Ambient Temperature = 85°C)
0.03
OUT
OUT
0.04
drops below 1.8V, then the output
in an overcurrent condition, it is
I
OUT
0.05
(A)
0.06
LIMIT
MIC2090/MIC2091
0.07
OUT
is reached I
M9999-070611-B
OUT
0.08
ON
drops below
OUT
OUT
). This plot
0.09
is pulled
is 2.5V
OUT
OUT
0.1