參數(shù)資料
型號(hào)： LM2587SX-3.3/NOPB
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 穩(wěn)壓器
英文描述： 5 A SWITCHING REGULATOR, 100 kHz SWITCHING FREQ-MAX, PSSO5
封裝： TO-263, 5 PIN
文件頁(yè)數(shù)： 2/27頁(yè)
文件大?。?/td> 819K
代理商： LM2587SX-3.3/NOPB
Flyback Regulator Operation
The LM2587 is ideally suited for use in the flyback regulator
topology. The flyback regulator can produce a single output
voltage, such as the one shown in Figure 4, or multiple
output voltages. In Figure 4, the flyback regulator generates
an output voltage that is inside the range of the input voltage.
This feature is unique to flyback regulators and cannot be
duplicated with buck or boost regulators.
The operation of a flyback regulator is as follows (refer to
Figure 4): when the switch is on, current flows through the
primary winding of the transformer, T1, storing energy in the
magnetic field of the transformer. Note that the primary and
secondary windings are out of phase, so no current flows
through the secondary when current flows through the pri-
mary. When the switch turns off, the magnetic field col-
lapses, reversing the voltage polarity of the primary and
secondary windings. Now rectifier D1 is forward biased and
current flows through it, releasing the energy stored in the
transformer. This produces voltage at the output.
The output voltage is controlled by modulating the peak
switch current. This is done by feeding back a portion of the
output voltage to the error amp, which amplifies the differ-
ence between the feedback voltage and a 1.230V reference.
The error amp output voltage is compared to a ramp voltage
proportional to the switch current (i.e., inductor current dur-
ing the switch on time). The comparator terminates the
switch on time when the two voltages are equal, thereby
controlling the peak switch current to maintain a constant
output voltage.
01231610
As shown in Figure 4, the LM2587 can be used as a flyback regulator by using a minimum number of external components. The switching waveforms of this
regulator are shown in Figure 5. Typical Performance Characteristics observed during the operation of this circuit are shown in Figure 6.
FIGURE 4. 12V Flyback Regulator Design Example
LM2587
www.national.com
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相關(guān)PDF資料
PDF描述
LM2588-12MWC 9.5 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, UUC
LM2588-12MDC 9.5 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, UUC
LM2588-ADJMWC 9.5 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, UUC
LM2588T-12/NOPB 9.5 A SWITCHING REGULATOR, 200 kHz SWITCHING FREQ-MAX, PSFM7
LM2590HV3.3MDC 3 A SWITCHING REGULATOR, 173 kHz SWITCHING FREQ-MAX, UUC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM2587SX-5.0 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
LM2587SX-5.0/NOPB 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
LM2587SXADJ 制造商:National Semiconductor 功能描述:Conv DC-DC Single Step Up 4V to 40V 6-Pin(5+Tab) TO-263 T/R
LM2587SX-ADJ 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
LM2587SX-ADJ/NOPB 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
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