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PDF MP4558 Data sheet ( Hoja de datos )
| Número de pieza | MP4558 | |
| Descripción | Step-Down Converter | |
| Fabricantes | MPS | |
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MP4558
1A, 2MHz, 55V
Step-Down Converter
DESCRIPTION
The MP4558 is a high-frequency, step-down
switching regulator with an integrated internal
high-side high-voltage power MOSFET. It
provides up to a 1A 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
automotive input. A 12µA shutdown-mode supply
current makes it suitable for battery-powered
applications.
A scaled-down switching frequency in light-load
conditions provides high power-conversion
efficiency over a wide load range while reducing
switching and gate driver losses.
The frequency fold-back prevents inductor current
runaway during startup and thermal shutdown
provides reliable, fault-tolerant operation.
By switching at 2MHz, the MP4558 can prevent
EMI (electromagnetic interference) noise
problems, such as those found in AM radio and
ADSL applications.
The MP4558 is available in an SOIC8E and a 10-
pin 3mm x 3mm QFN package.
TYPICAL APPLICATION
FEATURES
Wide 3.8V-to-55V Operating Input Range
250mΩ Internal Power MOSFET
Up to 2MHz Programmable Switching
Frequency
140μA Quiescent Current
Stable with Ceramic Capacitors
Internal Soft-Start
Up to 95% Efficiency
Output Adjustable from 0.8V to 52V
Available in SOIC8E and 3mm x 3mm
QFN10 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 the MPS website under Products, Quality Assurance
page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
MP4558 Rev. 1.01
www.MonolithicPower.com
10/28/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
1
http://www.Datasheet4U.com
1 page  
MP4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER
TYPICAL CHARACTERISTICS
MP4558 Rev. 1.01
www.MonolithicPower.com
10/28/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
5
5 Page 
MP4558 – 1A, 2MHz, 55V STEP-DOWN CONVERTER
Current Comparator and Current Limit
A current-sense MOSFET accurately senses the
current in the power MOSFET. This signal is then
fed to the high speed current comparator for
current-mode–control purposes, which uses it as
one of its inputs with the COMP voltage. When
the power MOSFET turns on, the comparator is
first blanked until the end of the turn-on transition
to avoid noise issues. When the sensed current
exceeds the COMP voltage, the comparator
output is low and the power MOSFET turns off.
The cycle-by-cycle maximum current of the
internal power MOSFET is internally limited.
Short-Circuit Protection
When the output is shorted to the ground, the
switching frequency folds back and the current
limit falls to reduce the short circuit current. When
the FB voltage equals 0V, the current limit falls to
about 50% of its full current limit. The FB voltage
reaches its 100% of its current limit when it
exceeds 0.4V
When the short-circuit FB voltage is low, the SS
drops by VFB and SS ≈ VFB + 100mV. If the short
circuit is removed, the output voltage recovers at
the SS rate. When FB is high enough, the
frequency and current limit return to normal
values.
Startup and Shutdown
If both VIN and VEN exceed their appropriate
thresholds, the chip starts. The reference block
starts first, generating stable reference voltage
and currents, and then the internal regulator is
enabled. The regulator provides stable supply for
the remaining circuitries.
While the internal supply rail is up, an internal
timer blanks the power MOSFET OFF for about
50µs to avoid start-up glitches. When the internal
soft-start block is enabled, it first holds its SS
output low to ensure the other circuits are ready
and then slowly ramps up.
Three events can shut down the chip: EN low, VIN
low and thermal shutdown. In shutdown, the
power MOSFET turns off first to avoid any fault
triggering. The COMP voltage and the internal
supply rail are then pulled down.
Programmable Oscillator
An external resistor—RFREQ connected from the
FREQ pin to GND—sets the MP4558 oscillating
frequency. Calculate the value of RFREQ from:
RFREQ
(kΩ)
=
100000
fS (kHz)
-
5
For fSW=500kHz, RFREQ=195kΩ.
MP4558 Rev. 1.01
www.MonolithicPower.com
10/28/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
11
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet MP4558.PDF ] | |
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