MP2490
1.5A, 36V, 700KHz Step-Down Converter
with Programmable Output Current Limit
The Future of Analog IC Technology
DESCRIPTION
The MP2490 is a monolithic step-down switch
mode converter with a programmable output
current limit. It achieves 1.5A continuous output
current over a wide input supply range with
excellent load and line regulation.
The maximum output current can be
programmed by sensing current through the
inductor DC resistance (DCR) or an accurate
sense resistor.
Fault condition protection includes cycle-by-cycle
current limiting and thermal shutdown.
The MP2490 requires a minimum number of
readily available standard external components.
The MP2490 is available in QFN10 (3mm x 3mm),
8-pin SOIC and PDIP packages.
FEATURES
•
•
•
•
•
•
•
•
•
•
•
Wide 4.5V to 36V Operating Input Range
Programmable up to 1.5A Output Current
Output Adjustable from 0.8V to 15V
Programmable Output Current Limit without
power loss
0.25Ω Internal Power MOSFET Switch
Stable with Low ESR Output Ceramic
Capacitors
95% Efficiency @ 500mA (Vo=5V)
Fixed 700KHz Frequency
Thermal Shutdown
Cycle-by-Cycle Over Current Protection
Available in QFN10 (3mm x 3mm), 8-Pin
SOIC and PDIP Packages
USB Power Supplies
Automotive Cigarette Lighter Adapters
Power Supply for Linear Chargers
APPLICATIONS
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“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
Efficiency vs.
Load Current
8
1
9
6
100
ISN
ISP
PGOOD BST
VIN
4.5V - 36V
V
IN
=8V
VIN
90
R8
C9
10nF
EFFICIENCY (%)
7
PGOOD
V-PULL-UP
EN
R5
MP2490
3
80
70
60
50
10
V
IN
=24V
V
IN
=12V
EN
SW
10
L1
D1
5V
VOUT
5
SS
FB
GND
2
4
GND
V
OUT
=5V
100
1000
LOAD CURRENT (mA)
10000
MP2490 Rev. 0.92
4/23/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
1
MP2490 – 1.5A, 36V, 700KHz STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT
ORDERING INFORMATION
Part Number
MP2490DQ
*
MP2490DS
MP2490CP
Package
QFN10 (3mm X 3mm)
SOIC8
PDIP8
Top Marking
T6
MP2490DS
MP2490CP
Free Air Temperature (T
A
)
–40°C to +85°C
–40°C to +85°C
0°C to +70°C
* For Tape & Reel, add suffix –Z (e.g. MP2490DQ–Z);
For RoHS, compliant packaging, add suffix –LF (e.g. MP2490DQ–LF–Z).
PACKAGE REFERENCE
TOP VIEW
VIN
GND
EN
FB
SS
1
2
3
4
5
10
9
8
7
6
SW
BST
PGOOD
ISP
ISN
VIN
GND
FB
SS
1
2
3
4
8
7
6
5
SW
BST
ISP
ISN
TOP VIEW
EXPOSED PAD
ON BACKSIDE
CONNECT TO GND
QFN10 (3mm X 3mm)
SOIC/PDIP
ABSOLUTE MAXIMUM RATINGS
(1)
Supply Voltage V
IN
....................................... 40V
V
SW
....................................... –0.3V to V
IN
+ 0.3V
V
BST
................................................... V
SW
+ 6.5V
V
ISN,
v
ISP
................................................0V to15V
All Other Pins ..............................–0.3V to +6.5V
(2)
Continuous Power Dissipation (T
A
= +25°C)
QFN10 (3mm x 3mm) ................................ 2.5W
SOIC8 ...................................................... 1.39W
PDIP8 ...................................................... 1.32W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature.............. –65°C to +150°C
Thermal Resistance
(4)
QFN10 (3mm x 3mm) .............50 ...... 12 ...
°C/W
SOIC8 .....................................90 ...... 45 ...
°C/W
PDIP8......................................95 ...... 55 ...
°C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The maximum allowable power dissipation is a function of the
maximum junction temperature T
J
(MAX), the junction-to-
ambient thermal resistance
θ
JA
, and the ambient temperature
T
A
. The maximum allowable continuous power dissipation at
any ambient temperature is calculated by P
D
(MAX) = (T
J
(MAX)-T
A
)/θ
JA
. Exceeding the maximum allowable power
dissipation will cause excessive die temperature, and the
regulator will go into thermal shutdown. Internal thermal
shutdown circuitry protects the device from permanent
damage.
3) The device is not guaranteed to function outside of its
operating conditions.
4) Measured on JEDEC51-7 4 layer PCB.
θ
JA
θ
JC
Recommended Operating Conditions
(3)
Supply Voltage V
IN
...........................4.5V to 36V
Output Voltage V
OUT
(V
IN
>16.5V) ....... 0.8V to 15
Output Voltage V
OUT
(V
IN
<=16.5V) ......................
.........................................0.8V to (V
IN
–1.5)V
Operating Junction Temperature (T
J
)
................................................ –40°C to +125°C
MP2490 Rev. 0.92
4/23/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
2
MP2490 – 1.5A, 36V, 700KHz STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT
ELECTRICAL CHARACTERISTICS
V
IN
= 12V, T
A
= +25°C, unless otherwise noted.
Parameters
Feedback Voltage
Feedback Bias Current
Switch On Resistance
Switch Leakage
Current Limit
(5)
Oscillator Frequency
Fold-Back Frequency
Boot-Strap Voltage
Minimum On Time
(5)
Under Voltage Lockout Threshold Rising
Under Voltage Lockout Threshold Hysteresis
EN Input Low Voltage
(6)
En Input High Voltage
(6)
EN Input Bias Current
(6)
Supply Current (Shutdown)
Supply Current (Quiescent)
Thermal Shutdown
(5)
Current Sense Voltage
Input Bias Current (ISN, ISP)
PGOOD Sink Current
Note:
5) Guaranteed by design
6) Enable function is only available for the MP2490DQ
Symbol
V
FB
I
BIAS(FB)
R
DS(ON)
Condition
4.5V
≤
V
IN
≤
36V
V
FB
= 0.8V
V
EN
= 0V, V
SW
= 0V
Min
0.785
Typ
0.805
10
0.25
0.1
Max
0.825
Units
V
nA
Ω
10
3
840
μA
A
KHz
KHz
V
ns
2.2
f
SW
V
BST
- V
SW
t
ON
V
FB
= 1V
3.0
V
FB
= 0.6V
V
FB
= 0V
560
2.6
700
200
5
100
3.3
200
3.6
0.4
V
mV
V
V
μA
μA
μA
°C
mV
uA
V
1.8
V
EN
= 0-6V
V
EN
=
0V
V
EN
=
2V, V
FB
= 1V
V
ISP
–V
ISN
V
ISP
, V
ISN
I
BIAS (ISN,ISP)
V
ISP
, V
ISN
0.4–15V
0.4–15V
90
–1
–10
–2
4
500
150
100
0.1
110
+1
0.3
10
10
800
Sink Current 5mA
MP2490 Rev. 0.92
4/23/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
3
MP2490 – 1.5A, 36V, 700KHz STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT
PIN FUNCTIONS
QFN10-3
Pin #
SOIC-8 /
PDIP-8
Pin#
1
Name
Description
1
2
3
4
2
3
5
6
7
8
4
5
6
9
7
10
8
Supply Voltage. The MP2490 operates from a +4.5V to +36V unregulated
input. C
IN
is needed to prevent large voltage spikes from appearing at the
VIN
input. Put C
IN
as close to the IC as possible. It is the drain of the internal
power device and power supply for the whole chip.
Ground. This pin is the voltage reference for the regulated output voltage.
For this reason care must be taken in its layout. This node should be placed
GND
outside of the D1 to C
IN
ground path to prevent switching current spikes from
inducing voltage noise into the part.
EN
On/Off Control Input. (Only available for the MP2490DQ)
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
FB
short circuit fault condition the frequency-fold-back comparator lowers the
oscillator frequency when the FB voltage is below 250mV.
Connect to an external capacitor used for Soft-Start and compensation for
SS
current limiting loop.
ISN
Negative Current Sense Input for load current limiting.
ISP
Positive Current Sense
Power good signal. When FB is less than 90% of 0.8V, PGOOD is low. It is
PGOOD an open-drain output. Use a high value pull-up resistor externally to pull it up
to system power supply.
Bootstrap. This capacitor is needed to drive the power switch’s gate above
the supply voltage. It is connected between SW and BST pins to form a
floating supply across the power switch driver. An on-chip regulator is used
BST
to charge up the external boot-strap capacitor. If the on-chip regulator is not
strong enough, one optional diode can be connected from IN or OUT to
charge the external boot-strap capacitor.
SW
Switch Output. It is the source of power device.
MP2490 Rev. 0.92
4/23/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
4
MP2490 – 1.5A, 36V, 700KHz STEP-DOWN WITH PROGRAMMABLE OUTPUT CURRENT LIMIT
TYPICAL PERFORMANCE CHARACTERISTICS
C1=C2=4.7μF, C3=C4=10μF, C8=0.1μF, L=12μH, T
A
=25ºC, unless otherwise noted
Efficiency vs.
Load Current
100
90
EFFICIENCY (%)
EFFICIENCY (%)
Efficiency vs.
Load Current
100
90
V
IN
=12V
80
70
60
50
10
V
IN
=24V
V
OUT
=5V
100
1000
LOAD CURRENT (mA)
10000
V
IN
=12V
EFFICIENCY (%)
Efficiency vs.
Load Current
100
90
V
IN
=24V
80
70
60
50
10
V
OUT
=12V
100
1000
LOAD CURRENT (mA)
10000
V
IN
=18V
V
IN
=8V
V
IN
=8V
80
70
60
50
10
V
IN
=24V
V
IN
=36V
V
OUT
=3.3V
100
1000
LOAD CURRENT (mA)
10000
Load Regulation
3.40
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
Load Regulation
5.10
OUTPUT VOLTAGE (V)
Load Regulation
12.3
12.2
12.1
12.0
11.9
11.8
11.7
0
V
IN
=36V
V
IN
=24V
V
IN
=15V
400 800 1200 1600 2000
LOAD CURRENT (mA)
3.36
3.32
3.28
3.24
3.20
5.06
5.02
4.98
4.94
4.90
V
IN
=8V
V
IN
=24V V
IN
=12V
V
IN
=5V
V
IN
=12V
V
IN
=24V
0
400 800 1200 1600 2000
LOAD CURRENT (mA)
0
400 800 1200 1600 2000
LOAD CURRENT (mA)
Peak Current vs.
Duty Cycle
3.2
OUTPUT VOLTAGE (V)
Current Regulation
5.5
4.5
3.5
2.5
1.5
0.5
90
0
0.5
1.0
1.5
2.0
LOAD CURRENT (A)
2.5
GAIN (dB)
Loop Gain Bode Plot
V
IN
=12V, V
OUT
=5V, I
OUT
=0.5A
60
40
135
V
IN
=12V, V
OUT
=5V
R: Sense to RS, L: Sense to DCR
PEAK CURRENT (A)
3.0
2.8
2.6
2.4
2.2
2.0
40
V
OUT
=3.3V
50
60
70
80
DUTY CYCLE (%)
Phase
Gain
90
PHASE DEGREE
R
L
20
0
-20
-40
-60
1
10
100
FREQUENCY (kHz)
45
0
-45
-90
-135
1000
MP2490 Rev. 0.92
4/23/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
5
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