參數(shù)資料
型號(hào): LM2577T-ADJ
廠商: NATIONAL SEMICONDUCTOR CORP
元件分類(lèi): 穩(wěn)壓器
英文描述: SIMPLE SWITCHER Step-Up Voltage Regulator
中文描述: 6 A SWITCHING REGULATOR, 62 kHz SWITCHING FREQ-MAX, PSFM5
封裝: TO-220, 5 PIN
文件頁(yè)數(shù): 20/27頁(yè)
文件大?。?/td> 889K
代理商: LM2577T-ADJ
Application Hints
(Continued)
C. Calculate the minimum value of C
C
D. Calculate the maximum ESR of the +V
OUT
and V
OUT
output capacitors in parallel.
This formula can also be used to calculate the maximum
ESR of a single output regulator.
At this point, refer to this same section in the
Step-Up Regu-
lator Design Procedure
for more information regarding the
selection of C
OUT
.
3. Output Voltage Selection
This section is for applications using the LM1577-ADJ/
LM2577-ADJ. Skip this section if the LM1577-12/LM2577-12
or LM1577-15/LM2577-15 is being used.
With the LM1577-ADJ/LM2577-ADJ, the output voltage is
given by
V
OUT
= 1.23V (1 + R1/R2)
Resistors R1 and R2 divide the output voltage down so it can
be compared with the LM1577-ADJ/LM2577-ADJ internal
1.23V reference. For a desired output voltage V
OUT
, select
R1 and R2 so that
4. Diode Selection
The switching diode in a flyback converter must withstand
the reverse voltage specified by the following equation.
A suitable diode must have a reverse voltage rating greater
than this. In addition it must be rated for more than the aver-
age and peak diode currents listed in Figure 19
5. Input Capacitor Selection
The primary of a flyback transformer draws discontinuous
pulses of current from the input supply. As a result, a flyback
regulator generates more noise at the input supply than a
step-up regulator, and this requires a larger bypass capacitor
to decouple the LM1577/LM2577 V
pin from this noise. For
most applications, a low ESR, 1.0 μF cap will be sufficient, if
it is connected very close to the V
IN
and Ground pins.
Duty Cycle
D
Primary Current Variation
I
P
Peak Primary Current
I
P(PK)
Switch Voltage when Off
V
SW(OFF)
Diode Reverse Voltage
Average Diode Current
Peak Diode Current
V
R
V
OUT+
N (V
IN
V
SAT
)
I
LOAD
I
D(AVE)
I
D(PK)
Short Circuit Diode Current
Power Dissipation of
LM1577/LM2577
P
D
DS011468-78
FIGURE 19. Flyback Regulator Formulas
www.national.com
20
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM2577T-ADJ/LB02 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
LM2577T-ADJ/LB03 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
LM2577T-ADJ/LF02 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
LM2577T-ADJ/LF03 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
LM2577T-ADJ/NOPB 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 STEP-UP VLTG REG RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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