參數(shù)資料
型號： LM2587S-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, PSSO5
封裝： TO-263, 5 PIN
文件頁數(shù)： 21/26頁
文件大小： 676K
代理商： LM2587S-ADJ
Application Hints
PROGRAMMING OUTPUT VOLTAGE
(SELECTING R
1
AND R
2
)
Referring to the adjustable regulator in Figure 41 the output
voltage is programmed by the resistors R
1
and R
2
by the fol-
lowing formula:
V
OUT
= V
REF
(1 + R
1
/R
2
)
Resistors R
and R
divide the output voltage down so that
it can be compared with the 1.23V internal reference. With
R
2
between 1k and 5k, R
1
is:
R
1
= R
2
(V
OUT
/V
REF
1)
For best temperature coefficient and stability with time, use
1% metal film resistors.
where V
REF
= 1.23V
where V
REF
= 1.23V
SHORT CIRCUIT CONDITION
Due to the inherent nature of boost regulators, when the out-
put is shorted (see Figure 41), current flows directly from the
input, through the inductor and the diode, to the output, by-
passing the switch. The current limit of the switch does not
limit the output current for the entire circuit. To protect the
load and prevent damage to the switch, the current must be
externally limited, either by the input supply or at the output
with an external current limit circuit. The external limit should
be set to the maximum switch current of the device, which is
5A.
In a flyback regulator application (Figure 42), using the stan-
dard transformers, the LM2587 will survive a short circuit to
the main output. When the output voltage drops to 80% of its
nominal value, the frequency will drop to 25 kHz. With a
lower frequency, off times are larger. With the longer off
times, the transformer can release all of its stored energy be-
fore the switch turns back on. Hence, the switch turns on ini-
tially with zero current at its collector. In this condition, the
switch current limit will limit the peak current, saving the de-
vice.
FLYBACK REGULATOR INPUT CAPACITORS
A flyback regulator draws discontinuous pulses of current
from the input supply. Therefore, there are two input capaci-
tors needed in a flyback regulator; one for energy storage
and one for filtering (see Figure 42). Both are required due to
the inherent operation of a flyback regulator. To keep a
stable or constant voltage supply to the LM2587, a storage
capacitor (
≥
100 μF) is required. If the input source is a reciti-
fied DC supply and/or the application has a wide tempera-
ture range, the required rms current rating of the capacitor
might be very large. This means a larger value of capaci-
tance or a higher voltage rating will be needed of the input
capacitor. The storage capacitor will also attenuate noise
which may interfere with other circuits connected to the
same input supply voltage.
DS012316-26
FIGURE 41. Boost Regulator
www.national.com
21
相關(guān)PDF資料
PDF描述
LM2587S-3.3 RP DPA 60 DUST CAP
LM2587S-12 CONNECTOR
LM2587SX-ADJ SIMPLE SWITCHER 5A Flyback Regulator
LM2587SX-3.3 SIMPLE SWITCHER 5A Flyback Regulator
LM2587SX-12 SIMPLE SWITCHER 5A Flyback Regulator
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM2587S-ADJ 制造商:Texas Instruments 功能描述:IC SWITCHING REG 5A ADJ SMD 2587
LM2587S-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
LM2587S-ADJ/NOPB 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu
LM2587SX-12 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-12/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
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進(jìn)入我的后臺，查看報(bào)價(jià)

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*