MIC2039
Evaluation Board
High-Accuracy, High-Side, Adjustable
Current Limit Power Switch
General Description
The MIC2039 is a high-side MOSFET power distribution
switch providing increased system reliability by using 5%
current limit accuracy.
The MIC2039 has an operating input voltage range from
2.5V to 5.5V, is internally current limited, and has thermal
shutdown to protect the device and system. The MIC2039
is offered with either active-high or active-low logic level
enable input controls. It has an open drain fault status
output flag with a built-in 32ms delay that asserts low
during overcurrent or thermal shutdown conditions.
The MIC2039 switch features an adjustable output current
limit that is resistor programmable from 0.2A to 2.5A. The
MIC2039 switch also offers a unique Kickstart feature,
which allows momentary high-current surges up to the
secondary current limit (I
LIMIT_2nd
) during startup or while
operating in steady state. This is useful for charging loads
with high inrush currents, such as capacitors. After an
overcurrent condition is established, these switches enter
into a constant current limit mode unless the die
temperature exceeds the thermal shutdown specification.
The MIC2039 is offered in both 6-pin SOT-23 and 6-pin
2mm x 2mm thin DFN packages. It has an operating
junction temperature range of
−40°C
to +125°C.
Requirements
The MIC2039 evaluation board requires a single power
supply to provide V
IN
. The V
IN
power supply must be able
to deliver a minimum of 2.5V and more than 1.5A
capability. The output load can either be active or passive.
Precautions
The evaluation board does not have reverse polarity
protection. Applying a negative voltage to the V
IN
terminal
can damage the device. In addition, the maximum V
IN
operating voltage of the MIC2039 evaluation board is 5.5V.
Exceeding 5.5V on V
IN
can permanently damage the
device.
Getting Started
1.
Connect an external supply to V
IN
terminal.
Apply the desired input voltage to the V
IN
and ground
terminals of the evaluation board, paying careful
attention to polarity and supply voltage. The user can
place an ammeter between the input supply and the
V
IN
terminal to the evaluation board. Make sure that
the supply voltage is monitored at the V
IN
terminal. The
ammeter and/or power lead resistance can reduce the
voltage supplied to the input.
2.
Connect the load to the V
OUT
and ground terminals.
The load can be either passive (resistive) or active (as
in an electronic load). The user can place an ammeter
between the load and the V
OUT
terminal. Make sure
that the output voltage is monitored at the V
OUT
terminal.
3.
Enable the switch.
The MIC2039 evaluation boards are configured for
default enable using a 10kΩ pull-up resistor from the
ENABLE pin to VIN. To disable the switch, place a
jumper short across the jumper pins at TP2.
4.
Fault detection
The MIC2039 is equipped with an error flag pin,
FAULT/. TP3 is provided to monitor the FAULT/ pin.
Ordering Information
Part Number
MIC2039-05AYM6 EV
Description
Evaluation board featuring the
MIC2039AYM6 Power Switch
Current limit is set for 500mA
Evaluation board featuring the
MIC2039AYM6 Power Switch
Current limit is set for 1A
Evaluation board featuring the
MIC2039AYMT Power Switch
Current limit is set for 500mA
Evaluation board featuring the
MIC2039AYMT Power Switch
Current limit is set for 1A
MIC2039-1AYM6 EV
MIC2039-05AYMT EV
MIC2039-1AYMT EV
Ramp Control is a trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
October 2012
M9999-100112-A
Micrel, Inc.
MIC2039 Evaluation Board
Application Information
Adjustable Current Limit
The factory sets the MIC2039-xYMx evaluation boards
for either a 500mA or 1A current limit. However,
connecting a resistor (R3) from the ILIMIT pin to GND
allows the current limit to be adjusted from 0.2A to 2.5A.
For the MIC2039-xYMT evaluation board, jumper TP4
must be shorted for R3 to connect to the ILIMIT pin of
the IC. The following equation determines the value of
R3:
R3
≅
289/I
LIMIT
where I
LIMIT
is the typical current limit from the electrical
table. If the output current exceeds the set current limit,
the MIC2039 switch enters constant current limit mode.
The maximum allowable current limit may be less than
the full specified and/or expected current if the MIC2039
is not mounted on a circuit board with sufficiently low
thermal resistance. Resistor values (1%) for select
current limit settings are shown in
Table 1.
I
LIMIT
0.2A
1.43kΩ
0.5A
576Ω
1.0A
287Ω
2A
143Ω
2.5A
115Ω
Eq. 1
R3
Table 1. Resistor Selection for Adjustable Current Limit
October 2012
2
M9999-100112-A
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