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參數(shù)資料
| 型號(hào)： | LP5550 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | PowerWise Technology Compliant Energy Management Unit |
| 中文描述： | PowerWise技術(shù)兼容的能源管理單位 |
| 文件頁數(shù)： | 22/25頁 |
| 文件大小： | 1056K |
| 代理商： | LP5550 |
Application Information
PWM/PFM FORCE REGISTER (R9)
By default, the LP5550 automatically transitions between
PFM and PWM to optimize efficiency. The PWM/PFM force
register (R9) provides the option to override the automatic
transition and force PFM or PWM operation (see R9 –
PWM/PFM Force Register declaration). Note that if the op-
erating mode of the regulator is forced to be PFM then the
switch current limit is reduced to 100 mA (50 mA average
load current).
EN/RESETN
The LP5550 can be shutdown via the ENABLE or RESETN
pins, or by issuing a shutdown command from PWI. To
disable the LP5550 via hardware (as opposed to the PWI
shutdown command), pull the ENABLE and/or the RESETN
pin(s) low. To enable the LP5550, both the ENABLE and the
RESETN pins must be high. Once enabled, the LP5550
engages the power-up sequence and all voltages return to
their default values.
When using PWI to issue a shutdown command, the PWI will
be disabled along with the regulators in the LP5550. To
re-enable the part, either the ENABLE, RESETN, or both
pins must be toggled (high – low – high). The part will then
enter the power-up sequence and all voltages will return to
their default values.
Figure 8
summarizes the ENABLE/
RESETN control.
The ENABLE and RESETN pins provide flexibility for system
control. In larger systems such as a mobile phone, it can be
advantageous to enable/disable a subsystem independently.
For example, the LP5550 may be powering the applications
processor in a mobile phone. The system controller can
power down the applications processor via the ENABLE pin,
but leave on other subsystems. When the phone is turned off
or in a fault condition, the system controller can have a
global reset command that is connected to all the sub-
systems (RESETN for the LP5550). However, if this type of
control is not needed, the ENABLE and RESETN pins can
be tied together and used as a single enable/disable pin.
INDUCTOR
A 10uH or 4.7uH inductor should be used with the LP5550.
The inductor should be rated to handle the peak load current
plus the ripple current:
CURRENT LIMIT
The switching converter in the LP5550 detects the peak
inductor current and limits it for protection (see Electrical
Characteristics table and/or Typical Performance section).
To determine the average current limit from the peak current
limit, the inductor size, input and output voltage, and switch-
ing frequency must be known. The LP5550 is designed to
work with a 4.7uH or 10uH inductor, so:
INPUT CAPACITOR
The input capacitor to the switching converter supplies the
AC switching current drawn from the switching action of the
internal power FETs. The input current of a buck converter is
discontinuous, so the ripple current supplied by the input
capacitor is large. The input capacitor must be rated to
handle this current:
The power dissipated in the input capacitor is given by:
The input capacitor must be rated to handle both the RMS
current and the dissipated power. A 10 μF ceramic capacitor
is recommended for the LP5550.
20154551
FIGURE 8. ENABLE and RESETN operation
L
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| LP5550SQ | PowerWise Technology Compliant Energy Management Unit |
| LP5550SQX | PowerWise Technology Compliant Energy Management Unit |
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| LP5951MF-1.3 | Micropower, 150mA Low-Dropout CMOS Voltage Regulator |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LP5550SQ | 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| LP5550SQ/NOPB | 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| LP5550SQX | 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| LP5550SQX/NOPB | 功能描述:電池管理 RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| LP5551 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:PowerWise⑩ Technology Compliant Energy Management Unit |
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