參數(shù)資料
型號(hào): LM2587T-ADJ
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類: 穩(wěn)壓器
英文描述: SIMPLE SWITCHER 5A Flyback Regulator
中文描述: 5 A SWITCHING REGULATOR, 100 kHz SWITCHING FREQ-MAX, PSFM5
封裝: BENT STAGGERED, TO-220, 5 PIN
文件頁數(shù): 10/26頁
文件大?。?/td> 676K
代理商: LM2587T-ADJ
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 out-
put 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 sec-
ondary 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.
Typical Performance Characteristics
DS012316-10
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
FIGURE 4. 12V Flyback Regulator Design Example
DS012316-11
A: Switch Voltage, 10 V/div
AC-Coupled
Horizontal: 2 μs/div
FIGURE 5. Switching Waveforms
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM2587T-ADJ 制造商:Texas Instruments 功能描述:SWITCHING REG 5A ADJ 2587 TO2205
LM2587T-ADJ/LB02 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Up 4V to 40V 5-Pin(5+Tab) TO-220 Rail
LM2587T-ADJ/LB03 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Up 4V to 40V 5-Pin(5+Tab) TO-220 Rail
LM2587T-ADJ/LF03 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
LM2587T-ADJ/NOPB 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 5A FLYBACK REG 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