MP28490
5A, 30V, 420kHz
Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
The MP28490 is a monolithic step-down switch
mode converter with a built in internal power
MOSFET. It achieves 5A continuous output
current over a wide input supply range with
excellent load and line regulation.
Current mode operation provides fast transient
response and eases loop stabilization.
Fault condition protection includes cycle-by-cycle
current limiting and thermal shutdown.
The MP28490 requires a minimum number of
readily available standard external components
and is available in an 8-pin SOIC package with
exposed pad.
FEATURES
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Wide 4.5V to 30V Operating Input Range
5A Output Current
50mΩ Internal Power MOSFET Switch
Power Good Indicator
Fixed 420kHz Frequency
Synchronizable up to 1.5MHz
Cycle-by-Cycle Over Current Protection with
hiccup
Thermal Shutdown
Output Adjustable from 0.8V to 15V
Stable with Low ESR Output Ceramic
Capacitors
Available in a Thermally Enhanced 8-Pin
SOIC Package
Digital Set Top Boxes
Personal Video Recorders
Broadband Communications
Flat Panel Television and Monitors
APPLICATIONS
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“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
8
IN
BST
2
3
VCC
SW
1
6
PG
OFF ON
7
EN/SYNC
GND
4
FB
5
MP28490 Rev.1.0
9/17/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
1
MP28490 – 5A, 30V, 420KHZ STEP-DOWN CONVERTER
PACKAGE REFERENCE
TOP VIEW
SW
BST
VCC
GND
1
2
3
4
8
7
6
5
IN
EN/SYNC
PG
FB
Supply Voltage V
IN
....................................... 32V
V
SW
....................... –0.3V (-5V for < 10ns) to 33V
V
BS
....................................................... V
SW
+ 6V
All Other Pins................................. –0.3V to +6V
Junction Temperature...............................150°C
Lead Temperature ....................................260°C
Storage Temperature ..............–65°C to +150°C
ABSOLUTE MAXIMUM RATINGS
(1)
Recommended Operating Conditions
(2)
EXPOSED PAD
ON BACKSIDE
Supply Voltage V
IN
........................... 4.5V to 30V
Output Voltage V
OUT
........................ 0.8V to 15V
Operating Temperature .............–40°C to +85°C
Package
SOIC8E
Temperature
–40°C to +85°C
Part Number*
MP28490DN
*
Thermal Resistance
(3)
SOIC8E .................................. 50 ...... 10...
°C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
θ
JA
θ
JC
For Tape & Reel, add suffix –Z (eg. MP28490DN–Z)
For RoHS Compliant Packaging, add suffix –LF
(eg. MP28490DN–LF–Z)
ELECTRICAL CHARACTERISTICS
V
IN
= 12V, T
A
= +25°C, unless otherwise noted.
Parameters
Feedback Voltage
Feedback Current
Switch On Resistance
(4)
Switch Leakage
Current Limit
(4)
Oscillator Frequency
Fold-back Frequency
Maximum Duty Cycle
Minimum On Time
Under Voltage Lockout Threshold Rising
Under Voltage Lockout Threshold Hysteresis
EN Input Low Voltage
EN Input High Voltage
EN Input Current
Sync Frequency Range (Low)
Sync Frequency Range (High)
Enable Turnoff Delay
Supply Current (Shutdown)
Supply Current (Quiescent)
Thermal Shutdown
Power Good Control
Power Good Threshold Rising
Power Good Threshold Hysteresis
PG Pin Level
Note:
4) Guaranteed by design.
Symbol Condition
V
FB
4.5V
≤
V
IN
≤
30V
I
FB
V
FB
= 0.8V
R
DS(ON)
V
EN
= 0V, V
SW
= 0V
f
SW
V
FB
= 0.6V
V
FB
= 0V
V
FB
= 0.6V
Min
0.788
240
25
85
3.9
t
ON
Typ
0.808
10
45
0
7.5
420
115
90
100
4.1
880
Max
0.828
10
9
600
205
4.3
0.4
1.2
V
EN
= 2V
V
EN
= 0V
F
SYNCL
F
SYNCH
T
OFF
V
EN
=
0V
V
EN
=
2V, V
FB
= 1V
2
0
300
1.5
5.0
0
0.9
150
0.69
V
PG
PG Sink 4mA
0.74
40
Units
V
nA
mΩ
μA
A
kHz
kHz
%
ns
V
mV
V
V
μA
kHz
MHz
μs
μA
mA
°C
V
mV
V
1.1
0.79
0.4
MP28490 Rev.1.0
9/17/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
2
MP28490 – 5A, 30V, 420KHZ STEP-DOWN CONVERTER
PIN FUNCTIONS
Pin #
1
2
3
4
Name
SW
Description
Switch Output.
Bootstrap. This capacitor is needed to drive the power switch’s gate above the supply
BST
voltage. It is connected between SW and BS pins to form a floating supply across the power
switch driver.
VCC
Bias Supply. Decouple this pin with a 1µF ceramic capacitor.
Ground. This pin is the voltage reference for the regulated output voltage. For this reason
GND
care must be taken in its layout. This node should be placed outside of the D1 to C1 ground
path to prevent switching current spikes from inducing voltage noise into the part.
Feedback. An external resistor divider from the output to GND, tapped to the FB pin sets
the output voltage. To prevent current limit run away during a short circuit fault condition the
FB
frequency foldback comparator lowers the oscillator frequency when the FB voltage is
below 250mV.
Power Good Indicator. The output of this pin is LOW if the output voltage is 10% less than
PG
the nominal voltage; otherwise it is an open drain.
EN/SYNC On/Off Control Input and Synchronization Pin.
Supply Voltage. The MP28490 operates from a +4.5V to +30V unregulated input. C1 is
IN
needed to prevent large voltage spikes from appearing at the input.
5
6
7
8
MP28490 Rev.1.0
9/17/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
3
MP28490 – 5A, 30V, 420KHZ STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
= 12V, V
OUT
= 3.3V, I
OUT
= 5A, T
A
= +25ºC, unless otherwise noted.
Efficiency vs
Output Current
ENABLED SUPPLY CURRENT (uA)
100
95
V
IN
=5V
V
IN
=12V
1100
1050
1000
950
900
850
800
0
Enabled Supply Current
vs Input Voltage
DISABLED SUPPLY CURRENT (uA)
Disabled Supply Current
vs Input Voltage
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
V
EN
=0V
0
10
20
30
40
EFFICIENCY (%)
90
85
80
75
70
1
V
IN
=30V
V
FB
=1V
10
20
30
INPUT VOLTAGE (V)
40
2
3
4
OUTPUT CURRENT (A)
5
V
CC
Regulator Line
Regulation
70
Case Temperature vs
Output Current
100
Operating Range
CASE TEMPERATURE ( C)
4.9
4.7
4.5
OUTPUT VOLTAGE (V)
60
50
40
30
20
10
0
0
1
2
3
4
5
OUTPUT CURRENT (A)
6
D
MAX
Limit
10
V
O_MAX
SPEC
V
CC
(V)
4.3
4.1
3.9
3.7
3.5
0
5
I
CC
=10mA
10
15
20 25
INPUT VOLTAGE (V)
30
1
V
FB_MIN
0.1
420KHz
0
5
10 15 20 25 30
INPUT VOLTAGE(V)
35
Load Regulation
NORMALIZED OUTPUT VOLTAGE
V
IN
=30V
V
IN
=12V
Line Regulation
NORMALIZED OUTPUT VOLTAGE
1.00035
1.00030
1.00025
1.00020
1.00015
1.00010
1.00005
1.00000
0.99995
5
9
I=5A
13 17 21 25 29
INPUT VOLTAGE (V)
33
9.5
9.0
Peak Current vs
Duty Cycle
1.005
1.000
0.995
0.990
0.985
0.980
0
PEAK CURRENT (A)
8.5
8.0
7.5
7.0
6.5
6.0
20
40
60
80
DUTY CYCLE (%)
100
1
2
3
4
OUTPUT CURRENT (A)
5
MP28490 Rev.1.0
9/17/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
4
MP28490 – 5A, 30V, 420KHZ STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
(continued)
V
IN
= 12V, V
OUT
= 3.3V, I
OUT
= 5A, T
A
= +25ºC, unless otherwise noted.
HICCUP Output Short
Power Up Without Load
Power Up With 5A Load
V
OUT
2V/div.
V
IN
10V/div.
V
OUT
2V/div.
V
IN
10V/div.
V
OUT
2V/div.
V
SW
5V/div.
I
INDUCTOR
5A/div.
V
SW
5V/div.
I
INDUCTOR
5A/div.
V
SW
5V/div.
I
INDUCTOR
5A/div.
2ms/div.
2ms/div.
Enable Startup
at Full Load
V
EN
5V/div.
V
OUT
2V/div.
V
EN
5V/div.
V
OUT
2V/div.
Enable Startup
at No Load
V
IN
200mV/div.
Input Ripple Voltage
V
SW
5V/div.
I
INDUCTOR
5A/div.
V
SW
5V/div.
I
INDUCTOR
5A/div.
V
SW
10V/div.
Output Ripple Voltage
Load Transient Response
V
OUT
10mV/div.
V
SW
5V/div.
V
OUT
100mV/div.
I
INDUCTOR
5A/div.
I
INDUCTOR
2A/div.
MP28490 Rev.1.0
9/17/2009
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2009 MPS. All Rights Reserved.
5
