MIC261203 Evaluation Board
28V, 12A HyperLight Load
®
Synchronous DC-DC Buck Regulator
SuperSwitcher IIG
TM
General Description
The MIC261203 DC-DC regulator operates over an input
supply range of 4.5V to 28V, and provides a regulated
output at up to 12A of output current. The output voltage
is adjustable to 0.8V with a typical accuracy of ±1%; the
device operates at a switching frequency of 600kHz. The
switching frequency remains fairly constant with changes
in input voltage and output load.
Micrel’s Hyper Light Load™ architecture provides the
same high-efficiency and ultra-fast transient response as
the Hyper Speed Control™ architecture under medium
to heavy loads, but also maintains high efficiency under
light load conditions by transitioning to
variable
frequency, discontinuous mode operation.
The MIC261203 utilizes an adaptive T
ON
ripple control
architecture. An undervoltage lockout feature is provided
to ensure proper operation under power-sag conditions.
An internal soft-start feature is provided to reduce the
inrush current. Foldback current limit and “hiccup” mode
short-circuit protection and thermal shutdown ensures
protection of the IC during fault conditions.
Note
: This evaluation board is for 12A applications.
The datasheet and supporting documentation can be
found on Micrel’s web site at:
www.micrel.com.
Getting Started
1.
Connect an external supply to the 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. An ammeter may be placed
between the input supply and the V
IN
terminal to
the evaluation board. Ensure 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).
An ammeter can be placed between the load
and the V
OUT
terminal. Ensure that the output
voltage is monitored at the V
OUT
terminal. V
OUT
can be set to 0.9V, 1.0V, 1.2V, 1.5V, 1.8V,
2.5V, 3.3V, or 5.0V by a jumper. If a different
voltage is needed, it can be adjusted by
changing the feedback resistors. See “Output
Voltage” section.
3.
Enable the MIC261203.
The EN pin is provided
on the evaluation board. The output of the
MIC261203 turns on when V
DD
exceeds the
UVLO threshold. The output of the MIC261203
may be turned off by shorting the EN pin to
ground. A connection on the board provides
easy access to the enable pin.
Requirements
The MIC261203 provides a 5V regulated output for input
voltage V
IN
ranging from 5.5V to 28V. When V
IN
< 5.5V,
V
DD
should be tied to PVIN pins to bypass the internal
linear regulator by a jumper. 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 VIN
terminal may damage the device. In addition, the
maximum V
IN
operating voltage of the MIC261203
evaluation board is 28V. Exceeding 29V on V
IN
could
damage the device.
Ordering Information
Part Number
Description
MIC261203YJL EV
12A HLL DC-DC Regulator
Evaluation Board
Hyper Light Load and Hyper Speed Control are trademarks of Micrel, Inc.
MLF and
MicroLead
Frame are registered trademarks of Amkor Technology, 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
July 2011
M9999-071511-A
Micrel, Inc.
MIC261203 10A Evaluation Board
them with the values that yield the desired output voltage.
Once R4 is selected, R7 can be calculated using:
Output Voltage
The output voltage on the MIC261203 evaluation board is
adjustable. It is set by adjusting the feedback resistors (R4
and one of R5, R6, R7, R8, R9, R10, R11, or R12) and
can be calculated as follows as an example:
R4
V
=
VREF
×
(1
+
)
OUT
R7
R7
=
R4
×
VREF
VOUT
−
VREF
For V
REF
= 0.8V:
VOUT
−
0.8V
The output voltage should not be set to exceed 5V due to
the 6.3V rating of the output capacitor and online
regulation limitations. Please refer to the “Setting Output
Voltage” section in the MIC261203 datasheet for more
information.
R7
=
R4
×
0.8V
where V
REF
= 0.8V.
The output voltage above is set at the factory for a 1.2V
output, but it can easily be changed by moving the jumper
to a respective position to get an indicated voltage on the
board. If a desired voltage is not shown on the board, it is
easily modified by removing R4 and R7 and replacing
July 2011
2
M9999-071511-A
Micrel, Inc.
MIC261203 10A Evaluation Board
Evaluation Board Performance
Efficiency (V
IN
= 5V)
vs. Output Current
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
Efficiency (V
IN
= 12V)
vs. Output Current
100
95
90
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
100
95
90
Efficiency (V
IN
= 12V)
vs. Output Current
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
100
95
90
EFFICIENCY (%)
EFFICIENCY (%)
85
80
75
70
65
60
EFFICIENCY (%)
85
80
75
70
65
60
55
50
0
3
6
9
12
V
IN
= 5V
85
80
75
70
65
60
55
50
15
V
IN
= 12V
0
3
6
9
12
15
55
50
0
V
IN
= 12V
3
6
9
12
15
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Thermal Derating*
vs. Ambient Temperature
18
16
1.8V
18
16
Thermal Derating*
vs. Ambient Temperature
18
16
2.5V
Thermal Derating*
vs. Ambient Temperature
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
14
12
10
8
6
4
2
0
-50
-25
0
25
50
75
100
125
V
IN
= 5V
V
OUT
= 1.8, 2.5, 3.3V
3.3V
14
12
10
8
6
4
2
0
-50
-25
0
V
IN
= 12V
5V
OUTPUT CURRENT (A)
14
12
10
8
6
4
2
0
V
IN
= 24V
V
OUT
= 0.8, 1.2, 2.5V
2.5V
0.8V
V
OUT
= 2.5, 3.3, 5V
25
50
75
100
125
-50
-25
0
25
50
75
100
125
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
Die Temperature*
: The temperature measurement was taken at the hottest point on the MIC261203 case mounted on a 5 square inch 4 layer, 0.62”,
FR-4 PCB with 2oz finish copper weight per layer, see Thermal Measurement section. Actual results will depend upon the size of the PCB, ambient
temperature and proximity to other heat emitting components.
July 2011
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M9999-071511-A
Micrel, Inc.
MIC261203 10A Evaluation Board
Evaluation Board Schematic
Schematic of MIC261203 Evaluation Board
(J11, R13, R15 are for testing purposes)
July 2011
4
M9999-071511-A
Micrel, Inc.
MIC261203 10A Evaluation Board
Bill of Materials
Item
C1
C2, C3
C15
C4, C5, C13
Part Number
Open
12105C475KAZ2A
GRM32ER71H475KA88L
C3225X7R1H475K
Open
12106D107MAT2A
GRM32ER60J107ME20L
C3225X5R0J107M
06035C104KAT2A
C6, C7, C10
GRM188R71H104KA93D
C1608X7R1H104K
0603ZC105KAT2A
C8
GRM188R71A105KA61D
C1608X7R1A105K
0603ZD225KAT2A
C9
GRM188R61A225KE34D
C1608X5R1A225K
06035C472KAZ2A
C12
C14
C11, C16
D1
GRM188R71H472K
C1608X7R1H472K
B41851F7227M
Open
SD103AWS
SD103AWS-7
SD103AWS
L1
R1
R2
R3
R4
R5
R6, R14, R17
R7
R8
R9
R10
R11
R12
HCF1305-1R0-R
CRCW06032R21FKEA
CRCW06032R00FKEA
CRCW060319K6FKEA
CRCW06032K49FKEA
CRCW060320K0FKEA
CRCW060310K0FKEA
CRCW06034K99FKEA
CRCW06032K87FKEA
CRCW06032K006FKEA
CRCW06031K18FKEA
CRCW0603806RFKEA
CRCW0603475RFKEA
MCC
(5)
Diodes Inc
(6)
Vishay
(7)
Manufacturer
AVX
(1)
Murata
(2)
TDK
(3)
AVX
(1)
Murata
(2)
TDK
(3)
AVX
(1)
Murata
(2)
TDK
(3)
Description
Qty
4.7µF Ceramic Capacitor, X7R, Size 1210, 50V
2
100µF Ceramic Capacitor, X5R, Size 1210, 6.3V
3
0.1µF Ceramic Capacitor, X7R, Size 0603, 50V
3
AVX
(1)
Murata
(2)
TDK
(3)
1.0µF Ceramic Capacitor, X7R, Size 0603, 10V
1
AVX
(1)
Murata
(2)
TDK
(3)
2.2µF Ceramic Capacitor, X5R, Size 0603, 10V
1
AVX
(1)
Murata
(2)
TDK
(3)
4.7nF Ceramic Capacitor, X7R, Size 0603, 50V
220µF Aluminum Capacitor, 35V
1
1
EPCOS
(4)
40V, 350mA, Schottky Diode, SOD323
1
1
1
1
1
1
1
3
1
1
1
1
1
1
Cooper Bussmann
(8)
1.0µH Inductor, 21A Saturation Current
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
Vishay Dale
(7)
2.21Ω Resistor, Size 0603, 1%
2.00Ω Resistor, Size 0603, 1%
19.6kΩ Resistor, Size 0603, 1%
2.49kΩ Resistor, Size 0603, 1%
20.0kΩ Resistor, Size 0603, 1%
10.0kΩ Resistor, Size 0603, 1%
4.99kΩ Resistor, Size 0603, 1%
2.87kΩ Resistor, Size 0603, 1%
2.00kΩ Resistor, Size 0603, 1%
1.18kΩ Resistor, Size 0603, 1%
806Ω Resistor, Size 0603, 1%
475Ω Resistor, Size 0603, 1%
July 2011
5
M9999-071511-A
嵌入式系统
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