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PDF MP1471AGJ-P Data sheet ( Hoja de datos )
| Número de pieza | MP1471AGJ-P | |
| Descripción | Step-Down Converter | |
| Fabricantes | MPS | |
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MP1471A
High-Efficiency, 3A
16V, 500kHz Synchronous,
Step-Down Converter In a 6-Pin TSOT 23
DESCRIPTION
The MP1471A is a high-frequency,
synchronous, rectified, step-down, switch-mode
converter with internal power MOSFETs. It
offers a very compact solution to achieve a 3A
output current over a wide input supply range,
with excellent load and line regulation. The
MP1471A has synchronous-mode operation for
higher efficiency over the output current-load
range.
Current-mode operation provides fast transient
response and eases loop stabilization.
Protection features include over-current
protection and thermal shutdown.
The MP1471A requires a minimal number of
readily-available,
standard,
external
components and is available in a space-saving
6-pin TSOT23 package.
FEATURES
Wide 4.5V-to-16V Operating Input Range
110mΩ/57mΩ Low-RDS(ON) Internal Power
MOSFETs
Proprietary Switching-Loss–Reduction
Technology
High-Efficiency Synchronous-Mode
Operation
Fixed 500kHz Switching Frequency
Internal AAM Power-Save Mode for High
Efficiency at Light Load
Internal Soft-Start
Over-Current Protection and Hiccup
Thermal Shutdown
Output Adjustable from 0.8V
Available in a 6-pin TSOT-23 package
APPLICATIONS
Game Consoles
Digital Set-Top Boxes
Flat-Panel Television and Monitors
General Purposes
All MPS parts are lead-free and adhere to the RoHS directive. For MPS green
status, please visit MPS website under Products, Quality Assurance page.
“MPS” and “The Future of Analog IC Technology” are registered trademarks of
Monolithic Power Systems, Inc.
TYPICAL APPLICATION
MP1471A Rev. 1.0
www.MonolithicPower.com
8/18/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
1
1 page  
MP1471A – SYNCHRONOUS, STEP-DOWN CONVERTER WITH INTERNAL MOSFETS
TYPICAL PERFORMANCE CHARACTERISTICS
Performance waveforms are tested on the evaluation board of the Design Example section.
VIN = 12V, VOUT = 3.3V, L = 4.7µH, TA = +25°C, unless otherwise noted.
MP1471A Rev. 1.0
www.MonolithicPower.com
8/18/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
5
5 Page 
MP1471A – SYNCHRONOUS, STEP-DOWN CONVERTER WITH INTERNAL MOSFETS
resistor to the VIN voltage limits the EN input
current to less than 100μA.
For example, with 12V connected to Vin,
RPULLUP≥ (12V-6.5V) 100μA =55kΩ
Connecting the EN pin directly to a voltage
source without any pullup resistor requires
limiting the amplitude of the voltage source to ≤
6V to prevent damage to the Zener diode.
Figure 4: 6.5V Zener Diode
Under-Voltage Lockout (UVLO)
Under-voltage lockout (UVLO) protects the chip
from operating at an insufficient supply voltage.
The MP1471A UVLO comparator monitors the
output voltage of the internal regulator, VCC.
The UVLO rising threshold is about 4.15V while
its falling threshold is consistently 3.8V.
Internal Soft-Start
Soft-start prevents the converter output voltage
from overshooting during startup. When the
chip starts, the internal circuit generates a soft-
start voltage (SS) that ramps up from 0V to
1.2V: When SS falls below the internal
reference (REF), SS overrides REF so that the
error amplifier uses SS as the reference; when
SS exceeds REF, the error amplifier resumes
using REF as its reference. The SS time is
internally set to 1.5ms.
Over-Current-Protection and Hiccup
The MP1471A has a cycle-by-cycle over-
current limit for when the inductor current peak
value exceeds the set current-limit threshold.
First, when the output voltage drops until FB
falls below the Under-Voltage (UV) threshold
(typically 140mV) to trigger a UV event, the
MP1471A enters hiccup mode to periodically
restart the part. This protection mode is
especially useful when the output is dead-
shorted to ground. This greatly reduces the
average short-circuit current to alleviate thermal
issues and to protect the regulator. The
MP1471A exits hiccup mode once the over-
current condition is removed.
Thermal Shutdown
Thermal shutdown prevents the chip from
operating at exceedingly high temperatures.
When the silicon die temperature exceeds
150°C, it shuts down the whole chip. When the
temperature falls below its lower threshold
(typically 130°C) the chip is enabled again.
Floating Driver and Bootstrap Charging
An external bootstrap capacitor powers the
floating power MOSFET driver. This floating
driver has its own UVLO protection, with a
rising threshold of 2.2V and a hysteresis of
150mV. VIN regulates the bootstrap capacitor
voltage internally through D1, M1, R4, C4, L1
and C2 (Figure 5). If (VIN-VSW) exceeds 5V, U2
will regulate M1 to maintain a 5V BST voltage
across C4.
Figure 5 : Internal Bootstrap Charging Circuit
Start-Up and Shutdown
If both VIN and EN exceed their respective
thresholds, the chip starts. The reference block
starts first, generating a stable reference
voltage and currents, and then the internal
regulator is enabled. The regulator provides a
stable supply for the remaining circuits.
Three events can shut down the chip: EN low,
VIN low, and thermal shutdown. The shutdown
procedure starts by initially blocking the
signaling path to avoid any fault triggering. The
COMP voltage and the internal supply rail are
then pulled down. The floating driver is not
subject to this shutdown command.
MP1471A Rev. 1.0
www.MonolithicPower.com
8/18/2013
MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
11
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet MP1471AGJ-P.PDF ] | |
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