- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄369785 > LM2595SX-12 Voltage-Mode SMPS Controller PDF資料下載
參數(shù)資料
| 型號： | LM2595SX-12 |
| 元件分類： | 基準電壓源/電流源 |
| 英文描述： | Voltage-Mode SMPS Controller |
| 中文描述： | 電壓模式開關(guān)電源控制器 |
| 文件頁數(shù)： | 23/28頁 |
| 文件大?。?/td> | 739K |
| 代理商： | LM2595SX-12 |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁當前第23頁第24頁第25頁第26頁第27頁第28頁
Application Information
(Continued)
The curves shown in Figure 19 and Figure 20 show the
LM2594 junction temperature rise above ambient tempera-
ture with a 500 mA load for various input and output volt-
ages. This data was taken with the circuit operating as a
buck switcher with all components mounted on a PC board
to simulate the junction temperature under actual operating
conditions. This curve is typical, and can be used for a quick
check on the maximum junction temperature for various con-
ditions, but keep in mind that there are many factors that can
affect the junction temperature.
DELAYED STARTUP
The circuit in Figure 21 uses the the ON /OFF pin to provide
a time delay between the time the input voltage is applied
and the time the output voltage comes up (only the circuitry
pertaining to the delayed start up is shown).As the input volt-
age rises, the charging of capacitor C1 pulls the ON /OFF pin
high, keeping the regulator off. Once the input voltage
reaches its final value and the capacitor stops charging, and
resistor R
pulls the ON /OFF pin low, thus allowing the cir-
cuit to start switching. Resistor R
is included to limit the
maximum voltage applied to the ON /OFF pin (maximum of
25V), reduces power supply noise sensitivity, and also limits
the capacitor, C1, discharge current. When high input ripple
voltage exists, avoid long delay time, because this ripple can
be coupled into the ON /OFF pin and cause problems.
This delayed startup feature is useful in situations where the
input power source is limited in the amount of current it can
deliver. It allows the input voltage to rise to a higher voltage
before the regulator starts operating. Buck regulators require
less input current at higher input voltages.
UNDERVOLTAGE LOCKOUT
Some applications require the regulator to remain off until
the input voltage reaches a predetermined voltage. An und-
ervoltage lockout feature applied to a buck regulator is
shown in Figure 22 while Figure 23 and Figure 24 applies
the same feature to an inverting circuit. The circuit in Figure
23 features a constant threshold voltage for turn on and turn
off (zener voltage plus approximately one volt). If hysteresis
is needed, the circuit in Figure 24 has a turn ON voltage
which is different than the turn OFF voltage. The amount of
hysteresis is approximately equal to the value of the output
voltage. If zener voltages greater than 25V are used, an ad-
ditional 47 k
resistor is needed from the ON /OFF pin to the
ground pin to stay within the 25V maximum limit of the ON
/OFF pin.
INVERTING REGULATOR
The circuit in Figure 25 converts a positive input voltage to a
negative output voltage with a common ground. The circuit
operates by bootstrapping the regulators ground pin to the
negative output voltage, then grounding the feedback pin,
the regulator senses the inverted output voltage and regu-
lates it.
DS012439-36
FIGURE 21. Delayed Startup
DS012439-37
FIGURE 22. Undervoltage Lockout
for Buck Regulator
DS012439-38
This circuit has an ON/OFF threshold of approximately 13V.
FIGURE 23. Undervoltage Lockout for Inverting Regulator
L
www.national.com
23
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2595SX-3.3 | Voltage-Mode SMPS Controller |
| LM2595SX-5.0 | Voltage-Mode SMPS Controller |
| LM2595SX-ADJ | Voltage-Mode SMPS Controller |
| LM2597-12 | SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator with Features(897.00 k) |
| LM2597-3.3 | SIMPLE SWITCHER Power Converter 150 kHz 0.5A Step-Down Voltage Regulator with Features(897.00 k) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2595SX-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 安裝風格:SMD/SMT |
| LM2595SX-3.3 | 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 安裝風格:SMD/SMT |
| LM2595SX-3.3/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 安裝風格:SMD/SMT |
| LM2595SX-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 安裝風格:SMD/SMT |
| LM2595SX-5.0/E7001023 | 制造商:Texas Instruments 功能描述: |
發(fā)布緊急采購，3分鐘左右您將得到回復。