MP4561
1.5A, 2MHz, 55V
Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
The MP4561 is a high frequency step-down
switching regulator with integrated internal high-
side high voltage power MOSFET. It provides
1.5A output with current mode control for fast loop
response and easy compensation.
The wide 3.8V to 55V input range accommodates
a variety of step-down applications, including
those in automotive input environment. A 12µA
shutdown mode supply 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.
By switching at 2MHz, the MP4561 is able to
prevent EMI (Electromagnetic Interference) noise
problems, such as those found in AM radio and
ADSL applications.
The MP4561 is available in small 3mm x 3mm
10-pin QFN with exposed pad package.
FEATURES
•
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•
•
•
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Wide 3.8V to 55V Operating Input Range
300mΩ Internal Power MOSFET
Up to 2MHz Programmable Switching
Frequency
140μA Quiescent Current
Ceramic Capacitor Stable
External Soft-Start
Up to 95% Efficiency
Output Adjustable from 0.8V to 52V
Available in 3x3mm 10-Pin QFN
High Voltage Power Conversion
Automotive Systems
Industrial Power Systems
Distributed Power Systems
Battery Powered Systems
APPLICATIONS
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Quality Assurance. “MPS” and “The
Future of Analog IC Technology” are Registered Trademarks of Monolithic
Power Systems, Inc.
TYPICAL APPLICATION
C4
100nF
10
V
IN
9
C1
10uF
100V
3
8
7
VIN
BST
SW
1.2
D1
EN
SS
FREQ
GND
6
COMP
4
C3
470pF
FB
5
L1
10uH
C7
NS
C2
22uF
6.3V
100
V
OUT
3.3V
90
V
IN
=12V
EFFICIENCY (%)
80
70
60
50
40
0
0.5
I
OUT
(A)
1
1.5
EN
MP4561
V
IN
=55V
C5
10nF
C6
NS
MP4561 Rev. 1.0
11/5/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
1
MP4561 – 1.5A, 2MHz, 55V STEP-DOWN CONVERTER
ORDERING INFORMATION
Part Number*
MP4561DQ
Package
QFN10( 3x3mm)
Top Marking
9C
*
For Tape & Reel, add suffix –Z (e.g. MP4561DQ–Z)
For RoHS compliant packaging, add suffix –LF (e.g. MP4561DQ–LF–Z)
PACKAGE REFERENCE
TOP VIEW
SW
SW
EN
COMP
FB
1
2
3
4
5
10
9
8
7
6
BST
VIN
SS
FREQ
GND
EXPOSED PAD
Connect to GND Plane
ABSOLUTE MAXIMUM RATINGS
(1)
Supply Voltage (V
IN
).....................–0.3V to +60V
Switch Voltage (V
SW
)............ –0.5V to V
IN
+ 0.5V
BST to SW .....................................–0.3V to +5V
All Other Pins .................................–0.3V to +5V
(2)
Continuous Power Dissipation (T
A
= +25°C)
............................................................. 2.5W
Junction Temperature ...............................150°C
Lead Temperature ....................................260°C
Storage Temperature.............. –65°C to +150°C
Thermal Resistance
(4)
3x3mm QFN10........................50 ...... 12 ...
°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 board.
θ
JA
θ
JC
Recommended Operating Conditions
(3)
Supply Voltage V
IN
...........................3.8V to 55V
Output Voltage V
OUT
.........................0.8V to 52V
Operating Junct. Temp. (T
J
).... –40°C to +125°C
MP4561 Rev. 1.0
11/5/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
2
MP4561 – 1.5A, 2MHz, 55V 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
Error Amp Voltage Gain
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
Minimum Switch On Time
(5)
Shutdown Supply Current
Quiescent Supply Current
Thermal Shutdown
Minimum Off Time
Minimum On Time
EN Up Threshold
EN Threshold Hysteresis
5) Derived from bench characterization. Not tested in production.
Symbol Condition
4.5V < V
IN
< 55V
V
FB
–40°C to +85°C
V
BST
– V
SW
= 5V
R
DS(ON)
–40°C to +85°C
V
EN
= 0V, V
SW
= 0V
–40°C to +85°C
G
CS
I
COMP
= ±3µA
V
FB
= 0.7V
V
FB
= 0.9V
–40°C to +85°C
0V < V
FB
< 0.8V, C
SS
=10nF
R
FREQ
= 95kΩ
–40°C to +85°C
V
EN
< 0.3V
No load, V
FB
= 0.9V
Hysteresis = 20°C
–40°C to +85°C
–40°C to +85°C
Min
0.780
0.771
220
200
1.9
1.7
Typ
0.800
300
1
2.5
4.5
400
120
10
-10
3.0
0.35
1.6
1
100
12
140
150
100
100
1.55
320
Max
0.820
0.829
395
475
3.1
3.3
Units
V
mΩ
μA
A
A/V
V/V
µA/V
µA
µA
V
V
ms
MHz
ns
µA
µA
°C
ns
ns
V
mV
2.7
2.4
3.3
3.6
0.8
0.7
1.2
1.3
20
1.4
1.3
130
1.7
1.8
MP4561 Rev. 1.0
11/5/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
3
MP4561 – 1.5A, 2MHz, 55V STEP-DOWN CONVERTER
PIN FUNCTIONS
QFN
Pin #
1, 2
3
4
5
Name
SW
EN
COMP
FB
GND,
Exposed Pad
FREQ
SS
VIN
BST
Description
Switch Node. This is the output from the high-side switch. A low V
F
Schottky rectifier to
ground is required. The rectifier 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 GM error amplifier. Control loop frequency
compensation is applied to this pin.
Feedback. This is the input to the error amplifier. An external resistive divider connected
between the output and GND is compared to the internal +0.8V reference to set the
regulation voltage.
Ground. It should be connected as close as possible to the output capacitor avoiding the
high current switch paths. Connect exposed pad to GND plane for optimal thermal
performance.
Switching Frequency Program Input. Connect a resistor from this pin to ground to set the
switching frequency.
Soft start programming mode. Connect a capacitor between SS and GND to set the soft
start time.
Input Supply. This supplies power to all the internal control circuitry, both BST regulators
and the 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. Connect a bypass capacitor between this pin and SW pin.
6
7
8
9
10
MP4561 Rev. 1.0
11/5/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
4
MP4561 – 1.5A, 2MHz, 55V STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS
V
IN
= 12V, V
OUT
=3.3V, C1 = 10µF, C2 = 22µF, L1 = 10µH and T
A
= +25°C, unless otherwise noted.
Efficiency @V
OUT
=2.5V
L1=10uH, fs=500kHz
100
90
100
Efficiency @V
OUT
=5V
L1=15uH, fs=500kHz
Vin=12V
V
OUT
AC Coupled
10mV/div
Output Voltage Ripple
I
OUT
=0.1A
Vin=12V
EFFICIENCY (%)
90
80
70
60
50
40
EFFICIENCY (%)
80
70
60
50
40
Vin=55V
Vin=48V
Vsw
10V/div
IL
500mA/div
0
0.5
1
1.5
0
0.5
1
1.5
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Output Voltage Ripple
I
OUT
=0.75A
V
OUT
AC Coupled
10mV/div
V
OUT
AC Coupled
10mV/div
Output Voltage Ripple
I
OUT
=1.5A
Vsw
10V/div
Vsw
10V/div
IL
500mA/div
IL
1A/div
MP4561 Rev. 1.0
11/5/2012
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
5
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