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参数资料
| 型号： | MP28275EL |
| 厂商： | MONOLITHIC POWER SYSTEMS INC |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, 1300 kHz SWITCHING FREQ-MAX, PDSO14 |
| 封装： | 3 X 4 MM, MO-229VGED-3, QFN-14 |
| 文件页数： | 2/14页 |
| 文件大小： | 372K |
| 代理商： | MP28275EL |
MP28275 – 5A, 7V, SYNCHRONOUS STEP-DOWN CONVERTER WITH INTERNAL MOSFETS
MP28275 Rev. 0.91
www.MonolithicPower.com
10
12/2/2009
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
2009 MPS. All Rights Reserved.
Figure 4—Startup Sequence Using External
Sync Clock Signal
Under-Voltage Lockout (UVLO)
Under-voltage lockout (UVLO) is implemented to
protect the chip from operating at insufficient
supply voltage. The MP28275 UVLO comparator
monitors the output voltage of the internal
regulator, VCC. The UVLO rising threshold is
about 4.0V while its falling threshold is a
consistent 3.2V.
Internal Soft-Start
The soft-start is implemented to prevent the
converter output voltage from overshooting
during startup. When the chip starts, the internal
circuitry generates a soft-start voltage (SS)
ramping up from 0V to 1.2V. When it is lower
than the internal reference (REF), SS overrides
REF so the error amplifier uses SS as the
reference. When SS is higher than REF, REF
regains control. The SS time is internally fixed to
4ms.
Over-Current-Protection and Hiccup
The MP28275 has cycle-by-cycle over current
limit when the inductor current peak value
exceeds
the
set
current
limit
threshold.
Meanwhile, output voltage starts to drop until FB
is below the Under-Voltage (UV) threshold,
typically 30% below the reference. Once a UV is
triggered, the MP28275 enters hiccup mode to
periodically restart the part. This protection mode
is especially useful when the output is dead-short
to ground. The average short circuit current is
greatly reduced to alleviate the thermal issue and
to protect the regulator. The MP28275 exits the
hiccup mode once the over current condition is
removed.
Thermal Shutdown
Thermal shutdown is implemented to prevent the
chip
from
operating
at
exceedingly
high
temperatures. When the silicon die temperature
is higher than 150
°C, it shuts down the whole
chip. When the temperature is lower than its
lower threshold, typically 140
°C, the chip is
enabled again.
Floating Driver and Bootstrap Charging
The floating power MOSFET driver is powered by
an external bootstrap capacitor. This floating
driver has its own UVLO protection. This UVLO’s
rising threshold is 2.2V with a hysteresis of
150mV. The bootstrap capacitor voltage is
regulated internally by VIN through D1, M3, C4,
L1 and C2 (Figure 5). If (VIN-VSW) is more than
5V, U2 will regulate M3 to maintain a 5V BST
voltage across C4.
SW
Figure 5—Internal Bootstrap Charging Circuit
Startup and Shutdown
If both VIN and EN are higher than 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.
Three events can shut down the chip: EN low,
VIN low and thermal shutdown. In the shutdown
procedure, the signaling path is first blocked 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.
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相关代理商/技术参数 |
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| MP28275EL-LF-P | 功能描述:开关变换器、稳压器与控制器 5A, 5V, 1.1MHz Sync Buck w/ PG RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| MP28275EL-LF-Z | 功能描述:开关变换器、稳压器与控制器 5A, 5V, 1.1MHz Sync Buck w/ PG RoHS:否 制造商:Texas Instruments 输出电压:1.2 V to 10 V 输出电流:300 mA 输出功率: 输入电压:3 V to 17 V 开关频率:1 MHz 工作温度范围: 安装风格:SMD/SMT 封装 / 箱体:WSON-8 封装:Reel |
| MP28315CN-LF | 制造商:Monolithic Power Systems 功能描述:3A, 16V, 340KHZ SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER - Rail/Tube |
| MP28315CN-LF-Z | 制造商:Monolithic Power Systems 功能描述:3A, 16V, 340KHZ SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER - Tape and Reel |
| MP28317DS-LF-Z | 制造商:Monolithic Power Systems 功能描述:- Tape and Reel |
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