參數(shù)資料
型號： LM5027AMH
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20
封裝： TSSOP-20
文件頁數(shù)： 6/28頁
文件大?。?/td> 561K
代理商： LM5027AMH
Soft-Start
The soft-start circuit allows the regulator to gradually increase
its output voltage until the steady state operating point is
reached; thereby reducing start-up stresses and surge cur-
rents. When bias power is supplied to the LM5027A, the SS
pin capacitor is discharged by an internal MOSFET. When the
voltages on the UVLO, OTP, VCC, and REF pins reach the
operating thresholds, the soft-start capacitor is released and
is charged with a 22 A current source. When the SS pin volt-
age reaches 1V, output pulses commence with a slowly in-
creasing duty cycle (refer to Figure 3, Figure 4 and Figure
5). The voltage on the SS pin eventually increases to 5V, while
the voltage at the PWM comparator is limited to the level re-
quired for regulation as determined by the voltage feedback
loop via the COMP pin. When the soft-start voltage reaches
4.0V, the capacitor on the SSSR pin is released and charged
with a 25 A current source (refer to Figure 3, Figure 4 and
Figure 5) . When the SSSR pin voltage reaches approximate-
ly 2.5V (refer to Figure 6), the internal synchronous rectifier
PWM circuit gradually increases the synchronous rectifier
drive duty cycle (OUTSR) in proportion the rising SSSR pin
voltage. Delaying the start of the SSSR gate drive pulses until
after the main soft-start is completed allows the output voltage
to reach regulation before the synchronous rectifiers begins
operation. This delay prevents the synchronous rectifier from
sinking current from the output in applications where the out-
put voltage may be pre-biased.
Soft-Stop
If the UVLO pin voltage falls below the 2.0V standby thresh-
old, but above the 0.4V shutdown threshold, the synchronous
rectification soft-start capacitor is discharged with a 20 A
current source which gradually disables the synchronous rec-
tifiers (refer to Figure 4). After the SSSR capacitor has been
discharged to 2.0V the soft-start and synchronous rectifica-
tion soft-start capacitors are quickly discharged to ground to
terminate PWM pulses at OUTA ,OUTB, and OUTSR. The
PWM pulses may cease before the SSSR voltage reduces
the synchronous rectifier duty cycle if the VCC or REF voltage
drops below the respective under-voltage thresholds during
the soft-stop process. This soft-stop method of turning off the
converter prevents oscillations in the synchronous rectifiers
during a shutdown sequence.
30111905
FIGURE 3. Soft-Start Timing
www.national.com
14
LM5027A
相關(guān)PDF資料
PDF描述
LM5027AMHX SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, PDSO20
LM5035AMH-1 SWITCHING CONTROLLER, 2000 kHz SWITCHING FREQ-MAX, PDSO28
LM5045MH SWITCHING CONTROLLER, 540 kHz SWITCHING FREQ-MAX, PDSO28
LM5045SQ SWITCHING CONTROLLER, 540 kHz SWITCHING FREQ-MAX, QCC28
LM5046SQ SWITCHING CONTROLLER, 540 kHz SWITCHING FREQ-MAX, QCC28
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM5027AMH/NOPB 功能描述:電壓模式 PWM 控制器 Active Clamp Pwm W/3A Sr Drv RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
LM5027AMHX/NOPB 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
LM5027ASQ/NOPB 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
LM5027ASQX/NOPB 功能描述:電壓模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
LM5027MH 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Voltage Mode Active Clamp Controller
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

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

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*