MIC261201 Evaluation Board
28V, 12A Hyper Speed Control™
Synchronous DC/DC Buck Regulator
SuperSwitcher II™
General Description
The MIC261201 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 Speed Control™ architecture allows for
ultra-fast transient response, while reducing the output
capacitance and it also makes (High V
IN
)/ (Low V
OUT
)
operation possible. The MIC261201 utilizes an adaptive
T
ON
ripple control architecture. An undervoltage lockout
feature is provided to ensure proper operation under
power-sag conditions. It also includes an internal soft-start
feature to reduce the inrush current. Foldback current limit
and “hiccup” mode short-circuit protection, as well as
thermal shutdown ensures protection of the IC during fault
conditions.
Note:
This evaluation board is for 12A applications.
The datasheet and other 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. 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). 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, adjust it by changing the feedback resistors.
See “Output Voltage” section.
3.
Enable the MIC261201.
The EN pin is provided on the
evaluation board. The output of the MIC261201 turns
on when V
DD
exceeds the UVLO threshold. Turn off he
output of the MIC261201 by shorting the EN pin to
ground. A connection on the board provides easy
access to the enable pin.
Requirements
The MIC261201 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.
Ordering Information
Part Number
MIC261201YJL EV
Description
12 A HSC DC-DC Regulator Evaluation
Board
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 MIC261201 evaluation board is
28V. Exceeding 29V on V
IN
could damage the device.
.
Hyper Speed Control is a trademark 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.
MIC261201 12A Evaluation Board
and replacing 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 MIC261201 evaluation board
is adjustable. Set it 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:
V
OUT
=
V
REF
×
(1
+
R4
)
R7
R7
=
For V
REF
= 0.8V:
R4
×
VREF
VOUT
−
VREF
R4
×
0.8V
where V
REF
= 0.8V.
The output voltage above is set at the factory for 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, modify it by removing R4 and R7
VOUT
−
0.8V
The output voltage should not be set to exceed 5V due
to the 6.3V rating of the output capacitor and on-line
regulation limitation. Please refer to the “Setting Output
Voltage” section in the MIC261201 datasheet for more
information.
R7
=
July 2011
2
M9999-071511-A
Micrel, Inc.
MIC261201 12A Evaluation Board
Evaluation Board Performance
100
95
90
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
V
IN
= 5V
Efficiency (V
IN
= 5V)
vs. Output Current
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
95
90
85
Efficiency (V
IN
= 24V)
vs. Output Current
5.0V
3.3V
2.5V
1.8V
1.5V
1.2V
1.0V
0.9V
0.8V
V
IN
= 24V
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
15
85
80
75
70
65
60
55
50
0
3
6
9
12
85
80
75
70
65
60
55
50
V
IN
= 12V
80
75
70
65
60
55
15
0
3
6
9
12
50
0
3
6
9
12
15
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Thermal Derating*
vs. Ambient Temperature
18
16
1.8V
Thermal Derating*
vs. Ambient Temperature
18
16
14
12
2.5V
OUTPUT CURRENT (A)
18
16
Thermal Derating*
vs. Ambient Temperature
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
OUTPUT CURRENT (A)
14
12
10
8
6
4
2
V
IN
= 24V
V
OUT
= 0.8, 1.2, 2.5V
2.5V
0.8V
10
8
6
4
2
0
-50
5V
V
IN
= 12V
V
OUT
= 2.5, 3.3, 5V
-25
0
25
50
75
100
125
0
-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 MIC261201 case mounted n a 5 square inch 4 layer, 0.62”, FR-
4 PCB with 2 oz finish copper weight per layer; see Thermal Measurement section. Actual results will depend on the size of the PCB, ambient
temperature, and the proximity to other heat-emitting components.
July 2011
3
M9999-071511-A
Micrel, Inc.
MIC261201 12A Evaluation Board
Evaluation Board Schematic
Schematic of MIC261201 Evaluation Board
(J11, R13, R15 are for testing purposes)
July 2011
4
M9999-071511-A
Micrel, Inc.
MIC261201 12A 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)
Description
Qty
4.7µF Ceramic Capacitor, X7R, Size 1210, 50V
2
AVX
(1)
Murata
(2)
TDK
(3)
AVX
(1)
Murata
(2)
TDK
(3)
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, X7R, 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
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