MIC2090-1YM5 TR Micrel Inc, MIC2090-1YM5 TR Datasheet - Page 15

• 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.
Functional Description
V
V
circuitry driving the switch and the input (source
connection) of the power MOSFET switch. V
drain connection of the power MOSFET and supplies
power to the load. In a typical circuit, current flows from
V
When the switch is disabled, current will not flow to the
load, except for a small unavoidable leakage current of a
few microamps (forward leakage current).
C
A minimum 1μF bypass capacitor positioned close to the
V
practice and required for proper operation of the switch.
This will control supply transients and ringing. Without a
sufficient bypass capacitor, large current surges or a
short may cause sufficient ringing on V
lead inductance) to cause erratic operation of the
switch’s control circuitry. For best performance, place a
ceramic capacitor next to the IC.
An additional 10µF (or greater) capacitor, positioned
close to the VIN and GND pins of the switch is
necessary if the distance between a larger bulk capacitor
and the switch is greater than three inches. This
additional capacitor limits input voltage transients at the
switch caused by fast changing input currents that occur
during a fault condition, such as current limit and thermal
shutdown.
When bypassing with capacitors of 10μF or more, it is
good practice to place a smaller value capacitor in
parallel with the larger to handle the high-frequency
components of any line transients. Values in the range of
0.1μF to 1μF are recommended. Again, good quality,
low-ESR capacitors, preferably ceramic, should be
chosen.
C
An output capacitor is required to reduce ringing and
voltage sag on the output during a transient condition. A
value between 1μF and 10μF is recommended.
A 10μF or larger capacitor should be used if the distance
between the MIC2090/MIC2091 and the load is greater
than
MIC2090/MIC2091 turns off in (typically) 20ns. This
extremely fast turn-off can cause an inductive spike in
the output voltage when the internal switch turns off
during an overcurrent condition. The larger value
capacitor prevents the output from glitching too low.
July 2011
IN
IN
IN
IN
IN
OUT
and V
to V
is both the power supply connection for the internal
and GND pins of the switch is both good design
three
OUT
OUT
toward the load.
inches.
The
internal
switch
IN
(from supply
OUT
in
is the
the
15
Limitations on C
The part may enter current limit when turning on with a
large output capacitance, which is an acceptable
condition. However, if the part remains in current limit for
a time greater than t
low. The maximum value of C
by Equation 1:
Where: I
specified values listed in the Electrical Characteristic
table and V
switch.
Current Sensing and Limiting
The MIC2090/MIC2091 protects the system power
supply
monitoring current through the on-chip power MOSFET.
Load current is monitored by means of a current mirror
in parallel with the power MOSFET switch. Current
limiting is invoked when the load exceeds the over-
current threshold. When current limiting is activated in
the -1 version, the output current is constrained to the
limit value, and remains at this level until either the
load/fault is removed, the load’s current requirement
drops below the limiting value, or the switch goes into
thermal shutdown.
enough to drop V
MOSFET turns off very quickly (typically 20ns). This
prevents excessive current from flowing through the
device and damaging the internal MOSFET.
The latch-off feature of the -2 version latches the output
off when the output current exceeds the overcurrent
threshold. V
the latch.
Enable Input
The EN pin is a TTL logic level compatible input which
turns the internal MOSFET switch on and off.
FAULT/ pin remains high when the EN pin is pulled low
and the output is turned off. Toggling the enable pin
resets the output after an OGI (output greater than input)
condition occurs. In the -2 version, toggling the enable
pin resets the output after an overcurrent event.
Fault Output
The FAULT/ is an N-channel open-drain output, which is
asserted LOW when the MIC2090/MIC2091 switch
either begins current limiting or enters thermal shutdown.
C
and
LIMIT_MIN
OUT_MAX
IN_MAX
IN
or the enable pin must be toggled to reset
load
OUT
OUT
and T
is the maximum input voltage to the
=
D_FAULT
I
from
below (typically) 1.8V, the internal
LIMIT_MIN
If the overcurrent fault is large
D_FAULT_MIN
, the FAULT/ pin will assert
damage
V
OUT
×
IN_MAX
T
D_FAULT_MI
may be approximated
are the minimum
MIC2090/MIC2091
by
M9999-070611-B
continuously
N
Eq. 1
The