MP1586
The Future of Analog IC Technology
3A, 28V, 50kHz to 400kHz
Step-Down Converter
DESCRIPTION
The MP1586 is a high frequency step-down
switching regulator with an integrated internal
high-side high voltage power MOSFET. It
provides 3A output with current mode control for
fast loop response and easy compensation.
The wide 4.5V to 28V input range accommodates
a variety of step-down applications, including
those in an automotive input environment. A
115µA operational quiescent current allows use in
battery-powered applications.
High power conversion efficiency over a wide
load range is achieved by scaling down the
switching frequency at light load condition to
reduce the switching and gate driving losses.
The frequency foldback helps prevent inductor
current runaway during startup and thermal
shutdown provides reliable, fault tolerant
operation.
The MP1586 is available in a thermally enhanced
SOIC8E package.
FEATURES
•
•
•
•
•
•
•
•
•
•
•
•
Wide 4.5V to 28V Operating Input Range
Programmable Switching Frequency from
50kHz to 400kHz
High-Efficiency Pulse Skipping Mode for
Light Load
Ceramic Capacitor Stable
Internal Soft-Start
Internally Set Current Limit without a
Current Sensing Resistor
Available in SOIC8E Package.
High Voltage Power Conversion
Automotive Systems
Industrial Power Systems
Distributed Power Systems
Battery Powered Systems
APPLICATIONS
“MPS” and “The Future of Analog IC Technology” are Registered Trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
C4
100nF
Efficiency vs.
Load Current
100
V
IN
=8V
1
D1
V
OUT
=5V,F
SW
=250kHz
8
V
IN
7
VIN
BST
SW
V
OUT
5V
90
EFFICIENCY (%)
80
70
60
50
40
0.01
V
IN
=24V
V
IN
=12V
EN
2
EN
MP1586
FB
4
6
FREQ
GND
5
COMP
3
C3
820pF
C6
NS
0.1
1
10
LOAD CURRENT(A)
MP1586 Rev. 0.91
1/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
1
MP1586 – 3A, 28V, 50kHz TO 400kHz STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
MP1586EN
Package
SOIC8E
Top Marking
MP1586EN
Free Air Temperature (T
A
)
–20°C to +85°C
* For Tape & Reel, add suffix –Z (e.g. MP1586EN–Z);
For RoHS Compliant Packaging, add suffix –LF. (e.g. MP1586EN–LF–Z)
PACKAGE REFERENCE
TOP VIEW
SW
EN
COMP
FB
1
2
3
4
8
7
6
5
BST
VIN
FREQ
GND
ABSOLUTE MAXIMUM RATINGS
(1)
Supply Voltage (V
IN
).....................–0.3V to +30V
Switch Voltage (V
SW
).............–0.3V to 30 + 0.3V
BST to SW .....................................–0.3V to +6V
All Other Pins .................................–0.3V to +6V
Continuous Power Dissipation
(T
A
= +25°C)
(2)
............................................................. 2.5W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature.............. –65°C to +150°C
Recommended Operating Conditions
(3)
Supply Voltage V
IN
........................... 4.5V to 28V
Output Voltage V
OUT
........................ 0.8V to 25V
Operating Junct. Temp. (T
J
) ....–20°C to +125°C
Thermal Resistance
(4)
SOIC8E .................................. 50 ...... 10...
°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 JESD51-7, 4-layer PCB.
θ
JA
θ
JC
MP1586 Rev. 0.91
1/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
2
MP1586 – 3A, 28V, 50kHz TO 400kHz STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS
V
IN
= 12V, V
EN
= 2.5V, V
COMP
= 1.4V, T
A
= +25°C, unless otherwise noted.
Parameter
Feedback Voltage
Upper Switch On Resistance
(5)
Upper Switch Leakage
Current Limit
COMP to Current Sense
Transconductance
(5)
Error Amp Voltage Gain
(5)
Error Amp Transconductance
Error Amp Min Source current
Error Amp Min Sink current
VIN UVLO Threshold
VIN UVLO Hysteresis
Soft-Start Time
(5)
Oscillator Frequency
Shutdown Supply Current
Quiescent Supply Current
Thermal Shutdown
Thermal Shutdown Hysteresis
Minimum Off Time
(5)
Minimum On Time
(5)
EN Up Threshold
EN Hysteresis
Note:
5) Guaranteed by design.
Symbol Condition
V
FB
R
DS(ON)
4.5V < V
IN
< 28V
V
BST
– V
SW
= 5V
V
EN
= 0V, V
SW
= 0V, V
IN
= 28V
Min
0.776
Typ
0.8
150
1
4.7
9
Max
0.824
Units
V
mΩ
μA
A
A/V
4.0
G
CS
I
COMP
= ±3µA
V
FB
= 0.7V
V
FB
= 0.9V
40
2.7
0V < V
FB
< 0.8V
R
FREQ
=100kΩ
V
EN
= 0V
No load, V
FB
= 0.9V
200
200
60
5
–5
3.0
0.35
1.5
250
12
115
150
15
100
100
1.5
300
80
3.3
V/V
µA/V
µA
µA
V
V
ms
kHz
µA
µA
°C
°C
ns
ns
V
mV
300
20
145
1.35
1.65
MP1586 Rev. 0.91
1/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
3
MP1586 – 3A, 28V, 50kHz TO 400kHz STEP-DOWN CONVERTER
PIN FUNCTIONS
SOIC
Pin #
1
2
3
4
Name
SW
EN
COMP
FB
Description
Switch Node. This is the output from the high-side switch. A low forward drop Schottky diode to
ground is required. The diode must be close to the SW pins to reduce switching spikes.
Enable Input. Pulling this pin below the specified threshold shuts the chip down. Pulling it up
above the specified threshold or leaving it floating enables the chip.
Compensation. This node is the output of the error amplifier. Control loop frequency
compensation is applied to this pin.
Feedback. This is the input to the error amplifier. The output voltage is set by a resistive divider
connected between the output and GND which scales down V
OUT
equal to the internal +0.8V
reference.
5
6
7
8
GND
Ground. It should be connected as close as possible to the output capacitor to shorten the high
Exposed
current switch paths. Connect exposed pad to GND plane for optimal thermal performance.
Pad
Switching Frequency Program Input. Connect a resistor from this pin to ground to set the
FREQ
switching frequency.
Input Supply. This supplies power to all the internal control circuitry, both BS regulators and the
VIN
high-side switch. A decoupling capacitor to ground must be placed close to this pin to minimize
switching spikes.
Bootstrap. This is the positive power supply for the internal floating high-side MOSFET driver.
BST
Connect a bypass capacitor between this pin and SW pin.
MP1586 Rev. 0.91
1/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
4
MP1586 – 3A, 28V, 50kHz TO 400kHz STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
= 12V, V
OUT
=5V, F
SW
=250kHz, C1 = 10µF, C2 = 2×22µF, L1= 22µH and T
A
= +25°C, unless
otherwise noted.
Efficiency vs.
Efficiency vs.
Load Current
Load Current
100
90
EFFICIENCY (%)
EFFICIENCY (%)
V
OUT
=2.5V, F
SW
=250kHz
V
IN
=5V
100
90
V
OUT
=3.3V, F
SW
=250kHz
V
IN
=8V
80
70
60
50
40
0.01
V
IN
=24V
V
IN
=12V
80
70
60
50
40
0.01
V
IN
=24V
V
IN
=12V
0.1
1
10
0.1
1
10
LOAD CURRENT(A)
LOAD CURRENT(A)
Oscillating Frequency vs.
R
FREQ
OSCILLATING FREQUENCY (kHz)
450
400
350
300
250
200
150
100
50
0
10
100
1000
MP1586 Rev. 0.91
1/8/2010
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2010 MPS. All Rights Reserved.
5
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