MIC1344 Evaluation Board
Smart, 3A, Two-Channel,
Power ORing Switch
General Description
Getting Started
The MIC1344 is an advanced two input, one output, hotswappable, power multiplexer. It has both automatic and
manual input selection (ASEL\ and BSEL\), and four status
outputs.
1. Set the ILIM resistors to the correct value for input
source capability and the load (see Equation 1). The
evaluation board is provided with a current limit of 3A.
The MIC1344 evalaution board provides a method to
evaluate the part, and understand its functionality. The
evaluation board is not intended to demonstrate the
minimum size or most compact PCB layout.
The basic parameters of the evaluation board are:
1. VINA or VINB supply voltage:
−
2.8V to 5.5V
2. OUT current:
−
0 to 3A
Datasheets and support documentation are available on
Micrel’s web site at: www.micrel.com.
2. Connect a power supply to the VINA (J2) and/or VINB
(J4), terminals.
3. Connect a 5V supply to VCC (J1 or TP1).
4. Connect the load to VOUT (J6).
5. Turn on the VIN power and observe the operation of
the MIC1344 in the status LEDs, and the output
voltage (see Table 2 for an explanation of the status
LEDs).
Ordering Information
Part Number
Description
MIC1344YFT EB
MIC1344 Smart, 3A, Two-Channel, Power
Oring Switch Evaluation Board
Power-Up Precautions
Applying a negative voltage to the VINA or VINB terminals
may damage the device. In addition, the maximum VIN
operating voltage of the MIC1344 evaluation board is 5.5V.
Typical Application
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 24, 2015
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MIC1344 Evaluation Board
Evaluation Board Description
section in the Application Information section of the
MIC1344 datasheet for further information.
The current limit for the MIC1344 VINA and VINB is set on
the board to be ≈3A by resistors R11 and R12 being 825Ω.
If a different current limit is desired, adjust R11 for VINA or
R12 for VINB using Equation 1:
RILIM =
2485
ICL − 146µA
Eq. 1
Where:
ICL = Desired current limit (A)
RILIM = Resistor value for ILIM pin (Ω)
Setting resistor RILIM equal to zero is not recommended as
it will disable current limiting.
The MIC1344 ENA and ENB are not connected to a supply
rail; the internal 570kΩ resistor on each of the enable pins
pulls the pins low, placing the part into automatic mode. If
another mode is desired the enable pins can be connected
to an external voltage VCC via jumpers TP3 or TP5 or
driven directly, see Evaluation Board Schematic. Table 1
shows how the MIC1344 will route the input power as
controlled by the ENA and ENB input pins.
Figure 1. MIC1344YFT Evaluation Board
LED Key
There are nine status LEDs included on the MIC1344
evaluation board, see Table 2. As seen in the Evaluation
Board Schematic, the blue LEDs (LED4, LED5, LED6 and
LED8) are associated with the functionality of the INA
input. The green LED’s (LED1, LED2, LED3 and LED9),
are associated with the functionality of the INB input. The
one white LED (LED10) is associated with OUT. When
ENA or ENB LEDs are turned on, then the enable input
control signals are high. Refer to Table 1 for an
explanation of the enable signals. STAOK or STBOK LEDs
will light only if a fault should occur. The MIC1344
datasheet includes a complete explanation of the STAOK
and STBOK and the input conditions that cause these pins
to go active low (low impedance). ASEL\ and BSEL\
indicate which of the two inputs (A or B), is selected. When
an input is selected, the associated LED turns on.
Table 1. ENA and ENB Input Power Selection
ENA
ENB
Power Input Selected
0
0
The higher voltage on either INA or INB
automatically selected if > VUVLO.
0
1
No input selected (can be used for
cascading other MIC1344 power inputs).
1
0
INA power input selected if VINA > VUVLO.
1
1
INB power input selected if VINB > VUVLO.
VCC is a supply pin to power up the pull-up resistors on
ASEL\, BSEL\, STAOK, STBOK, as well as drive ENA, and
ENB. VCC can be connected to VOUT or an external
supply, please see the “Digital Status Output Pins” sub-
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MIC1344 Evaluation Board
Table 2. MIC1344 Status LED Description
LED #
Color
Pin
Function
1
Green
STBOK
Lights when fault occurs on VINB, or thermal shutdown
2
Green
BSEL\
Lights when VINB is selected
3
Green
ENB
Lights when ENB is high
4
Blue
ENA
Lights when ENA is high
5
Blue
ASEL\
Lights when VINA is selected
6
Blue
STAOK
Lights when fault occurs on VINA, or thermal shutdown
8
Blue
VINA
Lights when VINA is above ≈2.5V
9
Green
VINB
Lights when VINB is above ≈2V
10
White
VOUT
Lights when VOUT voltage is above ≈2.5V
Table 3. MIC1344 Evaluation Board Test Points
Designation
Jumper Function
TP1
Power for LEDs and Enables (VCC).
TP2
“ ” side of TP2 is BSEL\, “O” side of TP2 is STBOK.
TP3
Putting a jumper across TP3 connects ENB to VCC
TP4
“ ” side of TP4 is ENB, “O” side of TP4 is ENA.
TP5
Putting a jumper across TP5 connects ENA to VCC
TP6
“ ” side of TP6 is ASEL\, “O” side of TP4 is STAOK.
TP7
Voltage for Input A (VINA).
TP8
Voltage for Input B (VINB).
TP9
Putting a jumper across TP9 adds a 100µF capacitor on the VOUT.
TP10
Putting a jumper across TP10 puts a 4Ω (5W) load resistor on the VOUT.
TP11
Putting a jumper across TP11 puts a 4Ω (5W) load resistor on the VOUT.
TP12
Putting a jumper across TP12 puts a 150Ω (5W) load resistor on VOUT.
TP13
Output Voltage (VOUT).
JP1
April 24, 2015
Header for connection to trouble shooting signals. See the Evaluation Board Schematic for details.
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MIC1344 Evaluation Board
Evaluation Board Schematic
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MIC1344 Evaluation Board
Bill of Materials
Item
Part Number
Manufacturer
(1)
C1, C5
C2012X5R1H104K085AA
TDK
C2, C6
Open
C3
C2012X5R1A106M
TDK
C4
C3216X5R1A107M160AC
TDK
Qty.
100nF Ceramic Capacitor, 50V, X5R, Size 0805
2
Open
2
10µF Ceramic Capacitor, 10V, X5R, Size 0805
1
100µF Ceramic Capacitor, 10V, X5R, Size 1206
1
470kΩ, Tolerance 1%, Size 0805
4
R1, R2, R5, R6
ERJ-6ENF4703V
R3, R4, R7,
R8, R9, R10,
R13, R14, R18
ERJ-6ENF4990V
Panasonic
499Ω, Tolerance 1%, Size 0805
9
R11, R12
ERJ-6ENF8250V
Panasonic
825Ω, Tolerance 1%, Size 0805
2
4Ω 10W 5% AXIAL
2
150Ω, Tolerance 1%, Size 2010
1
Smart, 3A, Two-Channel, Power ORing Switch
1
R15, R16
R17
U1
ALSR104R000FE12
RMCP2010FT150R
MIC1344YFT
Panasonic
(2)
Description
(3)
Vishay
Stackpole
(4)
(5)
Micrel, Inc.
Notes:
1. TDK: www.tdk.com.
2. Panasonic: www.industrial.panasonic.com.
3. Vishay: www.vishay.com.
4. Stackpole Electronics: www.seielect.com.
5. Micrel, Inc.: www.micrel.com.
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MIC1344 Evaluation Board
PCB Layout Recommendations
Top Layer
Mid-Layer 1
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MIC1344 Evaluation Board
PCB Layout Recommendations (Continued)
Mid-Layer 2
Bottom Layer
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MIC1344 Evaluation Board
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel, Inc. is a leading global manufacturer of IC solutions for the worldwide high-performance linear and power, LAN, and timing & communications
markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock
management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company
customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products.
Corporation headquarters and state-of-the-art wafer fabrication facilities are located in San Jose, CA, with regional sales and support offices and
advanced technology design centers situated throughout the Americas, Europe, and Asia. Additionally, the Company maintains an extensive network
of distributors and reps worldwide.
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical
implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
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© 2015 Micrel, Incorporated.
April 24, 2015
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