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PDF MP2451 Data sheet ( Hoja de datos )
| Número de pieza | MP2451 | |
| Descripción | Step-Down Converter | |
| Fabricantes | MPS | |
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The Future of Analog IC Technology
MP2451
36V, 2MHz, 0.6A
Step-Down Converter
DESCRIPTION
The MP2451 is a high frequency (2MHz) step-
down switching regulator with integrated
internal high-side high voltage power MOSFET.
It provides single 0.6A (or less) highly efficient
output with current mode control for fast loop
response.
The wide 3.3V to 36V input range
accommodates a variety of step-down
applications in automotive input environment. A
3μA shutdown mode 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.
Frequency fold-back helps prevent inductor
current runaway during start-up. Thermal
shutdown provides reliable, fault-tolerant
operation.
The MP2451 is available in the cost-effective
SOT23-6 and TSOT23-6 packages.
FEATURES
• 130μA Operating Quiescent Current
• Wide 3.3V to 36V Operating Input Range
• 500mΩ Internal Power MOSFET
• 2MHz fixed Switching Frequency
• Internally compensated
• Stable with Ceramic Output Capacitors
• Internal Soft-Start
• Precision Current Limit Without Current
Sensing Resistor
• > 90% Efficiency
• Output Adjustable from +0.8V to 0.8xVIN
• 3μA Low Shutdown Supply Current
• SOT23-6 and TSOT23-6 Packages
APPLICATIONS
• High Voltage Power Conversion
• Automotive Systems
• Industrial Power Systems
• Distributed Power Systems
• Battery Powered Systems
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
C3
33pF
1 BST
6
SW
MP2451
GND
VIN 5
C4
100nF
L1
VIN
C1
D1
3 FB
EN 4
Control
VOUT
5V/0.6A
Efficiency
VOUT=5V
95 VIN=8V
90
85
VIN=12V
VIN=24V
80
75
70 VIN=36V
65
60
55
50
0
0.1 0.2 0.3 0.4 0.5 0.6
OUTPUT CURRENT(A)
MP2451 Rev. 1.33
4/29/2014
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2014 MPS. All Rights Reserved.
1
1 page  
MP2451―36V, 2MHz, 0.6A, STEP-DOWN CONVERTER
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
VIN = 12V, C1 = 4.7µF, C2 = 10µF, L = 3.3µH and TA = +25°C, unless otherwise noted.
Short Circuit Entry
IOUT=0A to Short
Short Circuit Recovery
IOUT= Short to 0A
VOUT
2V/div.
IL
500mA/div
VOUT
2V/div.
IL
500mA/div
MP2451 Rev. 1.33
4/29/2014
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2014 MPS. All Rights Reserved.
5
5 Page 
MP2451―36V, 2MHz, 0.6A, STEP-DOWN CONVERTER
Compensation Components
The goal of compensation design is to shape the
converter transfer function to get a desired loop
gain. Lower crossover frequencies result in
slower line and load transient responses, while
higher crossover frequencies could cause system
unstable. A good rule of thumb is to set the
crossover frequency to approximately one-tenth
of the switching frequency. If an electrolytic
capacitor is used, the loop bandwidth is no higher
than 1/4 of the ESR zero frequency (fESR). fESR is
given by:
fESR
=
1
2π × C2 × RESR
The Table 3 lists the typical values of
compensation components for some standard
output voltages with various output capacitors
(ceramic) and inductors. The values of the
compensation components have been optimized
for fast transient responses and good stability at
given conditions.
Table 3—Compensation Values for Typical
Output Voltage/Capacitor Combinations
VOUT(V) L(µH) C2(µF) R2(kΩ) C3(pF)
1.2 2.2 10 249 22
2.5 2.2 10 57.6 22
3.3 2.2 10 40.2 33
5 3.3 10 23.7 33
12 6.2 10 8.87 47
Note:
With the compensation, the control loop has the bandwidth at about
1/10 switching frequency and the phase margin higher than 45
degree.
External Bootstrap Diode
An external bootstrap diode may enhance the
efficiency of the regulator. In below cases, an
external BST diode is recommended from the 5V
to BST pin:
z There is a 5V rail available in the system;
z VIN is no greater than 5V;
z VOUT is between 3.3V and 5V;
This diode is also recommended for high duty
cycle operation (when VOUT / VIN > 65%)
applications.
The bootstrap diode can be a low cost one such
as IN4148 or BAT54.
5V
BS
MP2451
0.1uF
SW
Figure 2—External Bootstrap Diode
At no load or light load, the converter may
operate in pulse skipping mode in order to
maintain the output voltage in regulation. Thus
there is less time to refresh the BS voltage. In
order to have enough gate voltage under such
operating conditions, the difference of VIN –VOUT
should be greater than 3V. For example, if the
VOUT is set to 3.3V, the VIN needs to be higher
than 3.3V+3V=6.3V to maintain enough BS
voltage at no load or light load. To meet this
requirement, EN pin can be used to program the
input UVLO voltage to VOUT+3V.
MP2451 Rev. 1.33
4/29/2014
www.MonolithicPower.com
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2014 MPS. All Rights Reserved.
11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet MP2451.PDF ] | |
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